diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index cae95cd..5472964 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -123,11 +123,7 @@
             android:screenOrientation="user"
             android:label="@string/archived_activity_title"
             android:theme="@style/BugleTheme.ArchivedConversationListActivity"
-            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversationlist.ConversationListActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity" />
 
         <!-- Displays the contents of a single conversation -->
         <activity
@@ -136,11 +132,7 @@
             android:screenOrientation="user"
             android:windowSoftInputMode="stateHidden|adjustResize"
             android:theme="@style/BugleTheme.ConversationActivity"
-            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversationlist.ConversationListActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity" />
 
         <!-- Blocked Participants -->
         <activity
@@ -149,11 +141,7 @@
             android:screenOrientation="user"
             android:label="@string/blocked_contacts_title"
             android:theme="@style/BugleTheme"
-            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversationlist.ConversationListActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity" />
 
         <!-- Full-screen photo viewer -->
         <activity
@@ -171,11 +159,7 @@
             android:theme="@style/BugleTheme.SettingsActivity"
             android:configChanges="orientation|screenSize|keyboardHidden"
             android:screenOrientation="user"
-            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversationlist.ConversationListActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversationlist.ConversationListActivity" />
 
         <activity
             android:name=".ui.appsettings.PerSubscriptionSettingsActivity"
@@ -183,11 +167,7 @@
             android:theme="@style/BugleTheme.SettingsActivity"
             android:configChanges="orientation|screenSize|keyboardHidden"
             android:screenOrientation="user"
-            android:parentActivityName="com.android.messaging.ui.appsettings.SettingsActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.appsettings.SettingsActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.appsettings.SettingsActivity" />
 
         <activity
             android:name=".ui.appsettings.ApplicationSettingsActivity"
@@ -197,10 +177,6 @@
             android:screenOrientation="user"
             android:parentActivityName="com.android.messaging.ui.appsettings.SettingsActivity"
             android:exported="true">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:exported="true"
-                android:value="com.android.messaging.ui.appsettings.SettingsActivity" />
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.DEFAULT" />
@@ -239,11 +215,7 @@
             android:screenOrientation="user"
             android:label="@string/people_and_options_activity_title"
             android:theme="@style/BugleTheme"
-            android:parentActivityName="com.android.messaging.ui.conversation.ConversationActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversation.ConversationActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversation.ConversationActivity" />
 
          <!-- License -->
         <activity android:name=".ui.LicenseActivity"
@@ -280,11 +252,8 @@
             android:configChanges="orientation|screenSize|keyboardHidden"
             android:screenOrientation="user"
             android:label="@string/vcard_detail_activity_title"
-            android:theme="@style/BugleTheme">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value=".ui.conversation.ConversationActivity" />
-        </activity>
+            android:theme="@style/BugleTheme"
+            android:parentActivityName="com.android.messaging.ui.conversation.ConversationActivity" />
 
         <!-- Attachment chooser -->
         <activity
@@ -293,11 +262,7 @@
             android:screenOrientation="user"
             android:label="@string/attachment_chooser_activity_title"
             android:theme="@style/BugleTheme"
-            android:parentActivityName="com.android.messaging.ui.conversation.ConversationActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value="com.android.messaging.ui.conversation.ConversationActivity" />
-        </activity>
+            android:parentActivityName="com.android.messaging.ui.conversation.ConversationActivity" />
 
         <activity
             android:name=".ui.debug.DebugMmsConfigActivity"
@@ -335,15 +300,6 @@
 
         <!-- Intents for Notification and Pre-KLP Delivery -->
         <!-- Registered with the highest possible priority (max_int) -->
-        <receiver android:name=".receiver.MmsWapPushReceiver"
-                  android:enabled="false"
-                  android:exported="true"
-                  android:permission="android.permission.BROADCAST_WAP_PUSH">
-            <intent-filter android:priority="2147483647">
-                <action android:name="android.provider.Telephony.WAP_PUSH_RECEIVED" />
-                <data android:mimeType="application/vnd.wap.mms-message" />
-            </intent-filter>
-        </receiver>
         <receiver android:name=".receiver.SmsReceiver"
                   android:enabled="false"
                   android:exported="true"
@@ -356,26 +312,6 @@
             </intent-filter>
         </receiver>
 
-        <!-- Intents for aborting SMS/MMS broadcasts pre-KLP -->
-        <!-- Registered for a priority just ahead of inbox Messaging apps (2) -->
-        <receiver android:name=".receiver.AbortMmsWapPushReceiver"
-                  android:enabled="false"
-                  android:exported="true"
-                  android:permission="android.permission.BROADCAST_WAP_PUSH">
-            <intent-filter android:priority="3">
-                <action android:name="android.provider.Telephony.WAP_PUSH_RECEIVED" />
-                <data android:mimeType="application/vnd.wap.mms-message" />
-            </intent-filter>
-        </receiver>
-        <receiver android:name=".receiver.AbortSmsReceiver"
-                  android:enabled="false"
-                  android:exported="true"
-                  android:permission="android.permission.BROADCAST_SMS">
-            <intent-filter android:priority="3">
-                <action android:name="android.provider.Telephony.SMS_RECEIVED" />
-            </intent-filter>
-        </receiver>
-
         <!-- Intents for KLP+ Delivery -->
         <receiver android:name=".receiver.MmsWapPushDeliverReceiver"
                   android:exported="true"
diff --git a/res/drawable-hdpi/fab_new_message_static_shadow.png b/res/drawable-hdpi/fab_new_message_static_shadow.png
deleted file mode 100644
index 22e1764..0000000
Binary files a/res/drawable-hdpi/fab_new_message_static_shadow.png and /dev/null differ
diff --git a/res/drawable-mdpi/fab_new_message_static_shadow.png b/res/drawable-mdpi/fab_new_message_static_shadow.png
deleted file mode 100644
index 2e24f0a..0000000
Binary files a/res/drawable-mdpi/fab_new_message_static_shadow.png and /dev/null differ
diff --git a/res/drawable-v21/contact_picker_tab_background_selector.xml b/res/drawable-v21/contact_picker_tab_background_selector.xml
deleted file mode 100644
index 59bdf95..0000000
--- a/res/drawable-v21/contact_picker_tab_background_selector.xml
+++ /dev/null
@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-    android:color="@color/contact_picker_tab_pressed" />
\ No newline at end of file
diff --git a/res/drawable-v21/fab_new_message_bg.xml b/res/drawable-v21/fab_new_message_bg.xml
deleted file mode 100644
index 8043f0f..0000000
--- a/res/drawable-v21/fab_new_message_bg.xml
+++ /dev/null
@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-    android:color="@color/fab_ripple" >
-
-    <item>
-        <shape android:shape="oval">
-            <solid android:color="@color/fab_color" />
-        </shape>
-    </item>
-
-</ripple>
\ No newline at end of file
diff --git a/res/drawable-v21/gallery_image_background_selector.xml b/res/drawable-v21/gallery_image_background_selector.xml
deleted file mode 100644
index 7486fad..0000000
--- a/res/drawable-v21/gallery_image_background_selector.xml
+++ /dev/null
@@ -1,21 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-        android:color="@color/gallery_image_pressed">
-    <item android:id="@android:id/mask"
-          android:drawable="@android:color/white" />
-</ripple>
diff --git a/res/drawable-v21/mediapicker_tab_button_background.xml b/res/drawable-v21/mediapicker_tab_button_background.xml
deleted file mode 100644
index 10c4474..0000000
--- a/res/drawable-v21/mediapicker_tab_button_background.xml
+++ /dev/null
@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-        android:color="@color/background_item_pressed" />
diff --git a/res/drawable-v21/transparent_button_background.xml b/res/drawable-v21/transparent_button_background.xml
deleted file mode 100644
index 10c4474..0000000
--- a/res/drawable-v21/transparent_button_background.xml
+++ /dev/null
@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-        android:color="@color/background_item_pressed" />
diff --git a/res/drawable-xhdpi/fab_new_message_static_shadow.png b/res/drawable-xhdpi/fab_new_message_static_shadow.png
deleted file mode 100644
index 7075cb9..0000000
Binary files a/res/drawable-xhdpi/fab_new_message_static_shadow.png and /dev/null differ
diff --git a/res/drawable-xxhdpi/fab_new_message_static_shadow.png b/res/drawable-xxhdpi/fab_new_message_static_shadow.png
deleted file mode 100644
index adfd569..0000000
Binary files a/res/drawable-xxhdpi/fab_new_message_static_shadow.png and /dev/null differ
diff --git a/res/drawable-xxxhdpi/fab_new_message_static_shadow.png b/res/drawable-xxxhdpi/fab_new_message_static_shadow.png
deleted file mode 100644
index e1d16a6..0000000
Binary files a/res/drawable-xxxhdpi/fab_new_message_static_shadow.png and /dev/null differ
diff --git a/res/drawable/contact_picker_tab_background_selector.xml b/res/drawable/contact_picker_tab_background_selector.xml
index 78c443b..59bdf95 100644
--- a/res/drawable/contact_picker_tab_background_selector.xml
+++ b/res/drawable/contact_picker_tab_background_selector.xml
@@ -14,8 +14,5 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 -->
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item
-        android:state_pressed="true"
-        android:drawable="@color/contact_picker_tab_pressed" />
-</selector>
\ No newline at end of file
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="@color/contact_picker_tab_pressed" />
\ No newline at end of file
diff --git a/res/drawable/fab_new_message_bg.xml b/res/drawable/fab_new_message_bg.xml
index 741b4b5..8043f0f 100644
--- a/res/drawable/fab_new_message_bg.xml
+++ b/res/drawable/fab_new_message_bg.xml
@@ -14,32 +14,13 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 -->
-<layer-list
-    xmlns:android="http://schemas.android.com/apk/res/android">
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="@color/fab_ripple" >
+
     <item>
-        <bitmap
-            android:src="@drawable/fab_new_message_static_shadow" />
+        <shape android:shape="oval">
+            <solid android:color="@color/fab_color" />
+        </shape>
     </item>
-    <item
-        android:left="2dp"
-        android:right="2dp"
-        android:bottom="@dimen/fab_padding_bottom">
-        <selector>
-            <item
-                android:state_pressed="true">
-                <shape
-                    android:shape="oval" >
-                    <solid
-                        android:color="@color/fab_pressed_color" />
-                </shape>
-            </item>
-            <item>
-                <shape
-                    android:shape="oval" >
-                    <solid
-                        android:color="@color/fab_color" />
-                </shape>
-            </item>
-        </selector>
-    </item>
-</layer-list>
\ No newline at end of file
+
+</ripple>
\ No newline at end of file
diff --git a/res/drawable/gallery_image_background_selector.xml b/res/drawable/gallery_image_background_selector.xml
index 0b902fd..7486fad 100644
--- a/res/drawable/gallery_image_background_selector.xml
+++ b/res/drawable/gallery_image_background_selector.xml
@@ -14,10 +14,8 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 -->
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item
-        android:state_pressed="true"
-        android:drawable="@color/gallery_image_pressed" />
-    <item
-        android:drawable="@android:color/transparent" />
-</selector>
\ No newline at end of file
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+        android:color="@color/gallery_image_pressed">
+    <item android:id="@android:id/mask"
+          android:drawable="@android:color/white" />
+</ripple>
diff --git a/res/drawable/mediapicker_tab_button_background.xml b/res/drawable/mediapicker_tab_button_background.xml
index 08dbf5c..10c4474 100644
--- a/res/drawable/mediapicker_tab_button_background.xml
+++ b/res/drawable/mediapicker_tab_button_background.xml
@@ -14,13 +14,5 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 -->
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item
-        android:state_pressed="true"
-        android:drawable="@color/background_item_pressed" />
-    <item
-        android:state_activated="true"
-        android:drawable="@color/background_item_activated" />
-    <item
-        android:drawable="@color/background_item_transparent" />
-</selector>
\ No newline at end of file
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+        android:color="@color/background_item_pressed" />
diff --git a/res/drawable/transparent_button_background.xml b/res/drawable/transparent_button_background.xml
index 08dbf5c..10c4474 100644
--- a/res/drawable/transparent_button_background.xml
+++ b/res/drawable/transparent_button_background.xml
@@ -14,13 +14,5 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 -->
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item
-        android:state_pressed="true"
-        android:drawable="@color/background_item_pressed" />
-    <item
-        android:state_activated="true"
-        android:drawable="@color/background_item_activated" />
-    <item
-        android:drawable="@color/background_item_transparent" />
-</selector>
\ No newline at end of file
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+        android:color="@color/background_item_pressed" />
diff --git a/res/drawable-v21/widget_item_background.xml b/res/drawable/widget_item_background.xml
similarity index 100%
rename from res/drawable-v21/widget_item_background.xml
rename to res/drawable/widget_item_background.xml
diff --git a/res/values-ldrtl-v21/styles.xml b/res/values-ldrtl-v21/styles.xml
deleted file mode 100644
index 4775979..0000000
--- a/res/values-ldrtl-v21/styles.xml
+++ /dev/null
@@ -1,23 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <style name="ComposeMessageViewAttachMediaButtonStyle">
-        <item name="android:paddingStart">@dimen/compose_message_attachment_padding_sides</item>
-        <item name="android:paddingEnd">@dimen/compose_message_attachment_padding_sides</item>
-        <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
-    </style>
-</resources>
diff --git a/res/values-ldrtl/styles.xml b/res/values-ldrtl/styles.xml
index 0c4e862..45258b2 100644
--- a/res/values-ldrtl/styles.xml
+++ b/res/values-ldrtl/styles.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
     Copyright (C) 2015 The Android Open Source Project
+    Copyright (C) 2024 The LineageOS Project
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -22,7 +23,7 @@
     <style name="ComposeMessageViewAttachMediaButtonStyle">
         <item name="android:paddingStart">@dimen/compose_message_attachment_padding_sides</item>
         <item name="android:paddingEnd">@dimen/compose_message_attachment_padding_sides</item>
-        <item name="android:background">?android:attr/selectableItemBackground</item>
+        <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
     </style>
 
     <style name="ConversationComposeSendText">
diff --git a/res/values-v17/styles.xml b/res/values-v17/styles.xml
deleted file mode 100644
index 01cec58..0000000
--- a/res/values-v17/styles.xml
+++ /dev/null
@@ -1,77 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <style name="GalleryGridItemViewCheckBoxStyle">
-        <item name="android:paddingEnd">4dp</item>
-    </style>
-
-    <style name="AttachmentGridItemViewCheckBoxStyle">
-        <item name="android:paddingEnd">4dp</item>
-    </style>
-
-    <style name="PeopleAndOptionsItemStyle">
-        <item name="android:paddingStart">16dp</item>
-        <item name="android:paddingEnd">16dp</item>
-    </style>
-
-    <style name="AudioAttachmentViewStyle">
-        <item name="android:paddingStart">16dp</item>
-        <item name="android:paddingEnd">16dp</item>
-    </style>
-
-    <style name="VcardAttachmentSingleStyle">
-        <item name="android:paddingStart">@dimen/message_text_left_right_padding</item>
-        <item name="android:paddingEnd">@dimen/message_text_left_right_padding</item>
-    </style>
-
-    <style name="PeopleListItemViewStyle">
-        <item name="android:paddingStart">16dp</item>
-    </style>
-
-    <style name="MessageVcardAttachmentStyle">
-        <item name="android:paddingStart">@dimen/message_text_left_right_padding</item>
-        <item name="android:paddingEnd">@dimen/message_text_left_right_padding</item>
-    </style>
-
-    <style name="CameraChooserFrameStyle">
-        <item name="android:paddingStart">16dp</item>
-    </style>
-
-    <style name="AddContactConfirmationTextStyle">
-        <item name="android:paddingStart">12dp</item>
-        <item name="android:paddingEnd">24dp</item>
-    </style>
-
-    <style name="ContactListItemDetailType">
-        <item name="android:paddingStart">12dp</item>
-    </style>
-
-    <style name="DebugMmsConfigItemStyle">
-        <item name="android:paddingStart">16dp</item>
-        <item name="android:paddingEnd">16dp</item>
-    </style>
-
-    <style name="ApnPreferenceLayoutStyle">
-        <item name="android:paddingStart">?android:attr/listPreferredItemPaddingStart</item>
-        <item name="android:paddingEnd">?android:attr/listPreferredItemPaddingEnd</item>
-    </style>
-
-    <style name="CopyContactDialogTextStyle">
-        <item name="android:paddingStart">@dimen/copy_contact_dialog_left_padding</item>
-        <item name="android:paddingEnd">@dimen/copy_contact_dialog_right_padding</item>
-    </style>
-</resources>
diff --git a/res/values-v21/colors.xml b/res/values-v21/colors.xml
deleted file mode 100644
index d51ad04..0000000
--- a/res/values-v21/colors.xml
+++ /dev/null
@@ -1,22 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <color name="notification_sender_text">#DE000000</color>
-    <color name="notification_secondary_text">#8A000000</color>
-    <color name="notification_tertiary_text">#8A000000</color>
-    <color name="notification_subject_color">#DE000000</color>
-</resources>
diff --git a/res/values-v21/dimens.xml b/res/values-v21/dimens.xml
deleted file mode 100644
index 466d2c8..0000000
--- a/res/values-v21/dimens.xml
+++ /dev/null
@@ -1,22 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <dimen name="fab_bottom_margin">16dp</dimen>
-    <dimen name="fab_left_right_margin">16dp</dimen>
-    <dimen name="fab_size">56dp</dimen>
-    <dimen name="fab_padding_bottom">0dp</dimen>
-</resources>
diff --git a/res/values-v21/styles.xml b/res/values-v21/styles.xml
deleted file mode 100644
index 4f54dd8..0000000
--- a/res/values-v21/styles.xml
+++ /dev/null
@@ -1,43 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-    Copyright (C) 2024 The LineageOS Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <style name="BugleTheme.ConversationActivity"
-        parent="@style/BugleTheme.ConversationActivityBase">
-        <item name="android:colorEdgeEffect">@color/conversation_edge_effect</item>
-    </style>
-
-    <style name="BugleTheme.DialogActivity" parent="@style/Theme.AppCompat.DayNight.Dialog">
-        <item name="android:windowNoTitle">false</item>
-        <item name="android:background">@color/window_background</item>
-        <item name="android:dialogCornerRadius">28dp</item>
-    </style>
-
-    <style name="ContactListItemDrawableIndicator">
-        <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
-    </style>
-
-    <style name="ConversationActionBarTitleTextStyle" parent="BugleActionBarTitleTextStyle">
-      <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
-    </style>
-
-    <style name="WidgetConversationListItemStyle">
-        <item name="android:background">@drawable/widget_item_background</item>
-        <item name="android:layout_height">72dp</item>
-    </style>
-
-</resources>
diff --git a/res/values-v27/styles.xml b/res/values-v27/styles.xml
deleted file mode 100644
index abcc39e..0000000
--- a/res/values-v27/styles.xml
+++ /dev/null
@@ -1,23 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2018 The LineageOS Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<resources>
-    <style name="BugleBaseTheme" parent="Theme.AppCompat.Light.DarkActionBar">
-        <item name="android:forceDarkAllowed">true</item>
-        <item name="android:navigationBarColor">@color/navigation_bar_bg</item>
-        <item name="android:windowLightNavigationBar">true</item>
-    </style>
-</resources>
diff --git a/res/values/colors.xml b/res/values/colors.xml
index c4e0fb4..fd8ca61 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
     Copyright (C) 2015 The Android Open Source Project
+    Copyright (C) 2024 The LineageOS Project
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -128,13 +129,13 @@
 
     <color name="contact_picker_hint_text_color">#40000000</color>
 
-    <color name="notification_sender_text">#9A9A9A</color>
-    <color name="notification_secondary_text">#FFFFFF</color>
-    <color name="notification_tertiary_text">#FFFFFF</color>
+    <color name="notification_sender_text">#DE000000</color>
+    <color name="notification_secondary_text">#8A000000</color>
+    <color name="notification_tertiary_text">#8A000000</color>
     <color name="wearable_notification_participants_count">#a2a2a2</color>
     <color name="notification_accent_color">@color/primary_color</color>
     <color name="notification_warning_color">#ff0000</color>
-    <color name="notification_subject_color">#99aaaaaa</color>
+    <color name="notification_subject_color">#DE000000</color>
 
     <color name="participant_list_text_primary">#4d4d4d</color>
     <color name="people_and_options_header_text">#6d6d6d</color>
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 952a0d7..8063812 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
     Copyright (C) 2015 The Android Open Source Project
+    Copyright (C) 2024 The LineageOS Project
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -112,12 +113,12 @@
     <dimen name="image_attachment_fallback_width">240dp</dimen>
     <dimen name="image_attachment_fallback_height">240dp</dimen>
 
-    <dimen name="fab_size">60dp</dimen>
-    <dimen name="fab_padding_bottom">4dp</dimen>
+    <dimen name="fab_size">56dp</dimen>
+    <dimen name="fab_padding_bottom">0dp</dimen>
     <dimen name="fab_elevation">2dp</dimen>
     <dimen name="fab_elevation_pressed">6dp</dimen>
-    <dimen name="fab_bottom_margin">12dp</dimen>
-    <dimen name="fab_left_right_margin">14dp</dimen>
+    <dimen name="fab_bottom_margin">16dp</dimen>
+    <dimen name="fab_left_right_margin">16dp</dimen>
     <dimen name="message_body_size_text_size">12sp</dimen>
 
     <dimen name="vcard_detail_group_indicator_width">40dp</dimen>
diff --git a/res/values/styles.xml b/res/values/styles.xml
index e5c7a51..e86e04f 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -17,18 +17,14 @@
 -->
 <resources>
     <!--
-        Base application theme, dependent on API level. This theme is replaced
-        by BugleBaseTheme from res/values-vXX/styles.xml on newer devices.
+        Base application theme
     -->
     <style name="BugleBaseTheme" parent="Theme.AppCompat.Light.DarkActionBar">
-        <!--
-            Theme customizations available in newer API levels can go in
-            res/values-vXX/styles.xml, while customizations related to
-            backward-compatibility can go here.
-        -->
+        <item name="android:forceDarkAllowed">true</item>
+        <item name="android:navigationBarColor">@color/navigation_bar_bg</item>
+        <item name="android:windowLightNavigationBar">true</item>
     </style>
 
-
     <!-- Application theme. -->
     <style name="BugleTheme" parent="BugleBaseTheme">
         <!-- All customizations that are NOT specific to a particular API-level can go here. -->
@@ -49,6 +45,7 @@
 
     <style name="BugleTheme.ConversationActivity"
         parent="@style/BugleTheme.ConversationActivityBase">
+        <item name="android:colorEdgeEffect">@color/conversation_edge_effect</item>
     </style>
 
     <style name="BugleTheme.ConversationActivityBase" parent="BugleTheme">
@@ -59,7 +56,10 @@
         <item name="android:fastScrollPreviewBackgroundRight">@drawable/contacts_fastscroll_label_right</item>
     </style>
 
-    <style name="BugleTheme.DialogActivity" parent="@style/Theme.AppCompat.Light.Dialog">
+    <style name="BugleTheme.DialogActivity" parent="@style/Theme.AppCompat.DayNight.Dialog">
+        <item name="android:windowNoTitle">false</item>
+        <item name="android:background">@color/window_background</item>
+        <item name="android:dialogCornerRadius">28dp</item>
     </style>
 
     <style name="BugleTheme.ConversationListActivity" parent="BugleTheme">
@@ -107,7 +107,7 @@
     </style>
 
     <style name="ConversationActionBarTitleTextStyle" parent="BugleActionBarTitleTextStyle">
-      <item name="android:background">?android:attr/selectableItemBackground</item>
+        <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
     </style>
 
     <style name="BuglePhotoViewTheme" parent="PhotoViewTheme.Translucent">
@@ -173,12 +173,12 @@
         <item name="android:background">@null</item>
     </style>
 
-    <style name="ContactListItemDetailType" parent="ContactListItemDetail">
-        <item name="android:paddingLeft">12dp</item>
+    <style name="ContactListItemDetailType">
+        <item name="android:paddingStart">12dp</item>
     </style>
 
     <style name="ContactListItemDrawableIndicator">
-        <item name="android:background">?android:attr/selectableItemBackground</item>
+        <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
     </style>
 
     <style name="RecipientEditTextView">
@@ -224,8 +224,8 @@
     </style>
 
     <style name="AudioAttachmentViewStyle">
-        <item name="android:paddingRight">16dp</item>
-        <item name="android:paddingLeft">16dp</item>
+        <item name="android:paddingStart">16dp</item>
+        <item name="android:paddingEnd">16dp</item>
     </style>
 
     <style name="ContactPickerHintText">
@@ -234,13 +234,13 @@
     </style>
 
     <style name="VcardAttachmentSingleStyle">
-        <item name="android:paddingRight">@dimen/message_text_left_right_padding</item>
-        <item name="android:paddingLeft">@dimen/message_text_left_right_padding</item>
+        <item name="android:paddingStart">@dimen/message_text_left_right_padding</item>
+        <item name="android:paddingEnd">@dimen/message_text_left_right_padding</item>
     </style>
 
     <style name="MessageVcardAttachmentStyle">
-        <item name="android:paddingRight">@dimen/message_text_left_right_padding</item>
-        <item name="android:paddingLeft">@dimen/message_text_left_right_padding</item>
+        <item name="android:paddingStart">@dimen/message_text_left_right_padding</item>
+        <item name="android:paddingEnd">@dimen/message_text_left_right_padding</item>
     </style>
 
     <style name="NotificationSenderText">
@@ -265,7 +265,7 @@
     </style>
 
     <style name="CameraChooserFrameStyle">
-        <item name="android:paddingLeft">16dp</item>
+        <item name="android:paddingStart">16dp</item>
     </style>
 
     <style name="ComposeMessageViewAttachMediaButtonStyle">
@@ -309,7 +309,7 @@
     </style>
 
     <style name="GalleryGridItemViewCheckBoxStyle">
-        <item name="android:paddingRight">22dp</item>
+        <item name="android:paddingEnd">4dp</item>
     </style>
 
     <style name="AttachmentPreviewAttachmentStyle">
@@ -342,23 +342,23 @@
         <item name="android:layout_gravity">left|center_vertical</item>
     </style>
 
-    <style name="AddContactConfirmationTextStyle" parent="ParticipantListItem">
-        <item name="android:paddingLeft">12dp</item>
-        <item name="android:paddingRight">24dp</item>
+    <style name="AddContactConfirmationTextStyle">
+        <item name="android:paddingStart">12dp</item>
+        <item name="android:paddingEnd">24dp</item>
     </style>
 
-    <style name="CopyContactDialogTextStyle" parent="ParticipantListItem">
-        <item name="android:paddingLeft">@dimen/copy_contact_dialog_left_padding</item>
-        <item name="android:paddingRight">@dimen/copy_contact_dialog_right_padding</item>
+    <style name="CopyContactDialogTextStyle">
+        <item name="android:paddingStart">@dimen/copy_contact_dialog_left_padding</item>
+        <item name="android:paddingEnd">@dimen/copy_contact_dialog_right_padding</item>
     </style>
 
     <style name="PeopleListItemViewStyle">
-        <item name="android:paddingLeft">16dp</item>
+        <item name="android:paddingStart">16dp</item>
     </style>
 
     <style name="PeopleAndOptionsItemStyle">
-        <item name="android:paddingRight">16dp</item>
-        <item name="android:paddingLeft">16dp</item>
+        <item name="android:paddingStart">16dp</item>
+        <item name="android:paddingEnd">16dp</item>
     </style>
 
     <style name="PeopleAndOptionsSectionHeader">
@@ -477,8 +477,8 @@
     </style>
 
     <style name="ApnPreferenceLayoutStyle">
-        <item name="android:paddingLeft">?android:attr/listPreferredItemPaddingStart</item>
-        <item name="android:paddingRight">?android:attr/listPreferredItemPaddingEnd</item>
+        <item name="android:paddingStart">?android:attr/listPreferredItemPaddingStart</item>
+        <item name="android:paddingEnd">?android:attr/listPreferredItemPaddingEnd</item>
     </style>
 
     <style name="SettingsListItem">
@@ -505,8 +505,8 @@
     </style>
 
     <style name="DebugMmsConfigItemStyle">
-        <item name="android:paddingLeft">16dp</item>
-        <item name="android:paddingRight">16dp</item>
+        <item name="android:paddingStart">16dp</item>
+        <item name="android:paddingEnd">16dp</item>
     </style>
 
     <style name="WidgetTitle" parent="@android:style/TextAppearance.Holo.Widget.ActionBar.Title">
@@ -612,11 +612,12 @@
     </style>
 
     <style name="WidgetConversationListItemStyle">
-        <item name="android:layout_height">80dp</item>
+        <item name="android:background">@drawable/widget_item_background</item>
+        <item name="android:layout_height">72dp</item>
     </style>
 
     <style name="AttachmentGridItemViewCheckBoxStyle">
-        <item name="android:paddingRight">4dp</item>
+        <item name="android:paddingEnd">4dp</item>
     </style>
 
     <style name="PromoScreenTextStyle">
diff --git a/res/xml-v21/preferences_application.xml b/res/xml-v21/preferences_application.xml
deleted file mode 100644
index d650489..0000000
--- a/res/xml-v21/preferences_application.xml
+++ /dev/null
@@ -1,79 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<!-- Preference screen definition for Bugle's application-wide settings -->
-<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
-
-    <!--  KLP+ only -->
-    <PreferenceScreen
-        android:key="@string/sms_disabled_pref_key"
-        android:title="@string/sms_disabled_pref_title"
-        android:persistent="false">
-        <intent
-            android:action="android.provider.Telephony.ACTION_CHANGE_DEFAULT">
-            <extra android:name="package" android:value="com.android.messaging" />
-        </intent>
-    </PreferenceScreen>
-    <PreferenceScreen
-        android:key="@string/sms_enabled_pref_key"
-        android:title="@string/sms_enabled_pref_title"
-        android:persistent="false">
-        <intent
-            android:action="android.settings.WIRELESS_SETTINGS">
-        </intent>
-    </PreferenceScreen>
-
-    <SwitchPreference
-        android:key="@string/send_sound_pref_key"
-        android:title="@string/send_sound_pref_title"
-        android:defaultValue="@bool/send_sound_pref_default"
-        android:persistent="true" />
-
-    <Preference
-        android:key="@string/notifications_pref_key"
-        android:title="@string/notifications_pref_title"
-        android:persistent="true" />
-
-    <SwitchPreference
-        android:key="@string/swipe_right_deletes_conversation_key"
-        android:title="@string/swipe_to_delete_conversation_pref_title"
-        android:summary="@string/swipe_to_delete_conversation_pref_summary"
-        android:defaultValue="false"
-        android:persistent="true" />
-
-    <PreferenceScreen
-            android:key="@string/advanced_pref_key"
-            android:title="@string/advanced_settings" />
-
-    <PreferenceCategory
-        android:key="@string/debug_pref_key"
-        android:title="@string/debug_category_pref_title">
-
-        <SwitchPreference
-            android:key="@string/dump_sms_pref_key"
-            android:title="@string/dump_sms_pref_title"
-            android:summary="@string/dump_sms_pref_summary"
-            android:defaultValue="@bool/dump_sms_pref_default" />
-
-        <SwitchPreference
-            android:key="@string/dump_mms_pref_key"
-            android:title="@string/dump_mms_pref_title"
-            android:summary="@string/dump_mms_pref_summary"
-            android:defaultValue="@bool/dump_mms_pref_default" />
-
-    </PreferenceCategory>
-
-</PreferenceScreen>
diff --git a/res/xml-v21/preferences_per_subscription.xml b/res/xml-v21/preferences_per_subscription.xml
deleted file mode 100644
index ae53f18..0000000
--- a/res/xml-v21/preferences_per_subscription.xml
+++ /dev/null
@@ -1,63 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-    Copyright (C) 2024 The LineageOS Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<!-- Preference screen definition for Bugle's subscription-specific settings -->
-<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
-
-    <PreferenceCategory
-        android:key="@string/mms_messaging_category_pref_key"
-        android:title="@string/mms_messaging_category_pref_title">
-
-        <Preference
-            android:title="@string/group_mms_pref_title"
-            android:key="@string/group_mms_pref_key"/>
-
-        <com.android.messaging.ui.appsettings.PhoneNumberPreference
-            android:key="@string/mms_phone_number_pref_key"
-            android:title="@string/mms_phone_number_pref_title" />
-
-        <SwitchPreference
-            android:key="@string/auto_retrieve_mms_pref_key"
-            android:title="@string/auto_retrieve_mms_pref_title"
-            android:summary="@string/auto_retrieve_mms_pref_summary"
-            android:defaultValue="@bool/auto_retrieve_mms_pref_default" />
-
-        <SwitchPreference
-            android:key="@string/auto_retrieve_mms_when_roaming_pref_key"
-            android:dependency="@string/auto_retrieve_mms_pref_key"
-            android:title="@string/auto_retrieve_mms_when_roaming_pref_title"
-            android:summary="@string/auto_retrieve_mms_when_roaming_pref_summary"
-            android:defaultValue="@bool/auto_retrieve_mms_when_roaming_pref_default" />
-
-    </PreferenceCategory>
-
-    <PreferenceCategory
-        android:key="@string/advanced_category_pref_key"
-        android:title="@string/advanced_category_pref_title">
-
-        <SwitchPreference
-            android:key="@string/delivery_reports_pref_key"
-            android:title="@string/delivery_reports_pref_title"
-            android:summary="@string/delivery_reports_pref_summary"
-            android:defaultValue="@bool/delivery_reports_pref_default" />
-
-        <PreferenceScreen
-            android:key="@string/sms_apns_key"
-            android:title="@string/sms_apns_title" />
-
-    </PreferenceCategory>
-</PreferenceScreen>
diff --git a/res/xml-v23/preferences_application.xml b/res/xml-v23/preferences_application.xml
deleted file mode 100644
index 7370c4a..0000000
--- a/res/xml-v23/preferences_application.xml
+++ /dev/null
@@ -1,80 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    Copyright (C) 2015 The Android Open Source Project
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-         http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
--->
-<!-- Preference screen definition for Bugle's application-wide settings -->
-<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
-
-    <!--  KLP+ only -->
-    <PreferenceScreen
-        android:key="@string/sms_disabled_pref_key"
-        android:title="@string/sms_disabled_pref_title"
-        android:persistent="false">
-        <intent
-            android:action="android.provider.Telephony.ACTION_CHANGE_DEFAULT">
-            <extra android:name="package" android:value="com.android.messaging" />
-        </intent>
-    </PreferenceScreen>
-    <!--  MNC+ only -->
-    <PreferenceScreen
-        android:key="@string/sms_enabled_pref_key"
-        android:title="@string/sms_enabled_pref_title"
-        android:persistent="false">
-        <intent
-            android:action="android.provider.Telephony.ACTION_CHANGE_DEFAULT">
-        </intent>
-    </PreferenceScreen>
-
-    <SwitchPreference
-        android:key="@string/send_sound_pref_key"
-        android:title="@string/send_sound_pref_title"
-        android:defaultValue="@bool/send_sound_pref_default"
-        android:persistent="true" />
-
-    <Preference
-        android:key="@string/notifications_pref_key"
-        android:title="@string/notifications_pref_title"
-        android:persistent="true" />
-
-    <SwitchPreference
-        android:key="@string/swipe_right_deletes_conversation_key"
-        android:title="@string/swipe_to_delete_conversation_pref_title"
-        android:summary="@string/swipe_to_delete_conversation_pref_summary"
-        android:defaultValue="false"
-        android:persistent="true" />
-
-    <PreferenceScreen
-            android:key="@string/advanced_pref_key"
-            android:title="@string/advanced_settings" />
-
-    <PreferenceCategory
-        android:key="@string/debug_pref_key"
-        android:title="@string/debug_category_pref_title">
-
-        <SwitchPreference
-            android:key="@string/dump_sms_pref_key"
-            android:title="@string/dump_sms_pref_title"
-            android:summary="@string/dump_sms_pref_summary"
-            android:defaultValue="@bool/dump_sms_pref_default" />
-
-        <SwitchPreference
-            android:key="@string/dump_mms_pref_key"
-            android:title="@string/dump_mms_pref_title"
-            android:summary="@string/dump_mms_pref_summary"
-            android:defaultValue="@bool/dump_mms_pref_default" />
-
-    </PreferenceCategory>
-
-</PreferenceScreen>
diff --git a/res/xml/preferences_application.xml b/res/xml/preferences_application.xml
index 7ca8dd7..788eea2 100644
--- a/res/xml/preferences_application.xml
+++ b/res/xml/preferences_application.xml
@@ -32,7 +32,7 @@
         android:title="@string/sms_enabled_pref_title"
         android:persistent="false">
         <intent
-            android:action="android.settings.WIRELESS_SETTINGS">
+            android:action="android.provider.Telephony.ACTION_CHANGE_DEFAULT">
         </intent>
     </PreferenceScreen>
 
diff --git a/src/android/support/v7/mms/DefaultApnSettingsLoader.java b/src/android/support/v7/mms/DefaultApnSettingsLoader.java
index 463f124..2721ee1 100644
--- a/src/android/support/v7/mms/DefaultApnSettingsLoader.java
+++ b/src/android/support/v7/mms/DefaultApnSettingsLoader.java
@@ -286,7 +286,7 @@ class DefaultApnSettingsLoader implements ApnSettingsLoader {
      */
     private void loadFromSystem(final int subId, final String apnName, final List<Apn> apns) {
         Uri uri;
-        if (Utils.supportMSim() && subId != MmsManager.DEFAULT_SUB_ID) {
+        if (subId != MmsManager.DEFAULT_SUB_ID) {
             uri = Uri.withAppendedPath(Telephony.Carriers.CONTENT_URI, "/subId/" + subId);
         } else {
             uri = Telephony.Carriers.CONTENT_URI;
diff --git a/src/android/support/v7/mms/DefaultCarrierConfigValuesLoader.java b/src/android/support/v7/mms/DefaultCarrierConfigValuesLoader.java
index 7e6e88b..2deef9d 100644
--- a/src/android/support/v7/mms/DefaultCarrierConfigValuesLoader.java
+++ b/src/android/support/v7/mms/DefaultCarrierConfigValuesLoader.java
@@ -68,12 +68,8 @@ class DefaultCarrierConfigValuesLoader implements CarrierConfigValuesLoader {
     }
 
     private void loadLocked(final int subId, final Bundle values) {
-        // For K and earlier, load from resources
         loadFromResources(subId, values);
-        if (Utils.hasMmsApi()) {
-            // For L and later, also load from system MMS service
-            loadFromSystem(subId, values);
-        }
+        loadFromSystem(subId, values);
     }
 
     /**
diff --git a/src/android/support/v7/mms/DefaultUserAgentInfoLoader.java b/src/android/support/v7/mms/DefaultUserAgentInfoLoader.java
index 8f18f6e..1c70990 100644
--- a/src/android/support/v7/mms/DefaultUserAgentInfoLoader.java
+++ b/src/android/support/v7/mms/DefaultUserAgentInfoLoader.java
@@ -72,13 +72,11 @@ class DefaultUserAgentInfoLoader implements UserAgentInfoLoader {
     }
 
     private void loadLocked() {
-        if (Utils.hasUserAgentApi()) {
-            // load the MMS User agent and UaProfUrl from TelephonyManager APIs
-            final TelephonyManager telephonyManager = (TelephonyManager) mContext.getSystemService(
-                    Context.TELEPHONY_SERVICE);
-            mUserAgent = telephonyManager.getMmsUserAgent();
-            mUAProfUrl = telephonyManager.getMmsUAProfUrl();
-        }
+        // load the MMS User agent and UaProfUrl from TelephonyManager APIs
+        final TelephonyManager telephonyManager = (TelephonyManager) mContext.getSystemService(
+                Context.TELEPHONY_SERVICE);
+        mUserAgent = telephonyManager.getMmsUserAgent();
+        mUAProfUrl = telephonyManager.getMmsUAProfUrl();
         if (TextUtils.isEmpty(mUserAgent)) {
             mUserAgent = DEFAULT_USER_AGENT;
         }
diff --git a/src/android/support/v7/mms/MmsHttpClient.java b/src/android/support/v7/mms/MmsHttpClient.java
index 4cbb201..20fe08f 100644
--- a/src/android/support/v7/mms/MmsHttpClient.java
+++ b/src/android/support/v7/mms/MmsHttpClient.java
@@ -392,17 +392,13 @@ public class MmsHttpClient {
      * @return the phone number text
      */
     private String getSelfNumber() {
-        if (Utils.supportMSim()) {
-            final SubscriptionManager subscriptionManager = SubscriptionManager.from(mContext);
-            final SubscriptionInfo info = subscriptionManager.getActiveSubscriptionInfo(
-                    SmsManager.getDefaultSmsSubscriptionId());
-            if (info != null) {
-                return info.getNumber();
-            } else {
-                return null;
-            }
+        final SubscriptionManager subscriptionManager = SubscriptionManager.from(mContext);
+        final SubscriptionInfo info = subscriptionManager.getActiveSubscriptionInfo(
+                SmsManager.getDefaultSmsSubscriptionId());
+        if (info != null) {
+            return info.getNumber();
         } else {
-            return mTelephonyManager.getLine1Number();
+            return null;
         }
     }
 
@@ -413,15 +409,11 @@ public class MmsHttpClient {
      */
     private String getSimOrLocaleCountry() {
         String country = null;
-        if (Utils.supportMSim()) {
-            final SubscriptionManager subscriptionManager = SubscriptionManager.from(mContext);
-            final SubscriptionInfo info = subscriptionManager.getActiveSubscriptionInfo(
-                    SmsManager.getDefaultSmsSubscriptionId());
-            if (info != null) {
-                country = info.getCountryIso();
-            }
-        } else {
-            country = mTelephonyManager.getSimCountryIso();
+        final SubscriptionManager subscriptionManager = SubscriptionManager.from(mContext);
+        final SubscriptionInfo info = subscriptionManager.getActiveSubscriptionInfo(
+                SmsManager.getDefaultSmsSubscriptionId());
+        if (info != null) {
+            country = info.getCountryIso();
         }
         if (!TextUtils.isEmpty(country)) {
             return country.toUpperCase();
@@ -439,13 +431,8 @@ public class MmsHttpClient {
      * @return the Base64 encoded NAI string to use as HTTP header
      */
     private String getEncodedNai(final String naiSuffix) {
-        String nai;
-        if (Utils.supportMSim()) {
-            nai = getNaiBySystemApi(
-                    getSlotId(Utils.getEffectiveSubscriptionId(MmsManager.DEFAULT_SUB_ID)));
-        } else {
-            nai = getNaiBySystemProperty();
-        }
+        String nai = getNaiBySystemApi(
+                getSlotId(Utils.getEffectiveSubscriptionId(MmsManager.DEFAULT_SUB_ID)));
         if (!TextUtils.isEmpty(nai)) {
             Log.i(MmsService.TAG, "NAI is not empty");
             if (!TextUtils.isEmpty(naiSuffix)) {
diff --git a/src/android/support/v7/mms/MmsManager.java b/src/android/support/v7/mms/MmsManager.java
index c825d3e..e43baf9 100644
--- a/src/android/support/v7/mms/MmsManager.java
+++ b/src/android/support/v7/mms/MmsManager.java
@@ -175,7 +175,7 @@ public class MmsManager {
      * @return true if forced to use legacy APIs or platform doesn't supports MMS APIs.
      */
     public static boolean shouldUseLegacyMms() {
-        return sForceLegacyMms || !Utils.hasMmsApi();
+        return sForceLegacyMms;
     }
 
     /**
@@ -187,10 +187,6 @@ public class MmsManager {
      * @return a Bundle containing the overrides
      */
     private static Bundle getConfigOverrides(final int subId) {
-        if (!Utils.hasMmsApi()) {
-            // If MMS API is not present, it is not necessary to compute overrides
-            return null;
-        }
         Bundle overrides = null;
         synchronized (sConfigOverridesMap) {
             overrides = sConfigOverridesMap.get(subId);
diff --git a/src/android/support/v7/mms/MmsNetworkManager.java b/src/android/support/v7/mms/MmsNetworkManager.java
index afcab8c..0956bc7 100644
--- a/src/android/support/v7/mms/MmsNetworkManager.java
+++ b/src/android/support/v7/mms/MmsNetworkManager.java
@@ -23,7 +23,6 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
-import android.os.Build;
 import android.os.SystemClock;
 import android.util.Log;
 
@@ -350,16 +349,7 @@ class MmsNetworkManager {
      * @return The change's network type
      */
     private static int getConnectivityChangeNetworkType(final Intent intent) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
-            return intent.getIntExtra(ConnectivityManager.EXTRA_NETWORK_TYPE, TYPE_NONE);
-        } else {
-            final NetworkInfo info = intent.getParcelableExtra(
-                    ConnectivityManager.EXTRA_NETWORK_INFO);
-            if (info != null) {
-                return info.getType();
-            }
-        }
-        return TYPE_NONE;
+        return intent.getIntExtra(ConnectivityManager.EXTRA_NETWORK_TYPE, TYPE_NONE);
     }
 
     private static String getMmsConnectivityResultString(int result) {
diff --git a/src/android/support/v7/mms/Utils.java b/src/android/support/v7/mms/Utils.java
index 06deeb7..43b973d 100644
--- a/src/android/support/v7/mms/Utils.java
+++ b/src/android/support/v7/mms/Utils.java
@@ -19,11 +19,9 @@ package android.support.v7.mms;
 
 import android.content.Context;
 import android.content.res.Configuration;
-import android.os.Build;
 import android.telephony.SmsManager;
 import android.telephony.SubscriptionInfo;
 import android.telephony.SubscriptionManager;
-import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 import android.util.Log;
 
@@ -34,33 +32,6 @@ import java.net.URL;
  * Utility methods
  */
 class Utils {
-    /**
-     * Check if MMS API is available
-     *
-     * @return true if MMS API is available, false otherwise
-     */
-    static boolean hasMmsApi() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
-    }
-
-    /**
-     * Check if support multi-SIM
-     *
-     * @return true if MSIM is supported, false otherwise
-     */
-    static boolean supportMSim() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1;
-    }
-
-    /**
-     * Check if support APIs for getting UserAgent and UAProfUrl
-     *
-     * @return true if those APIs are supported, false otherwise
-     */
-    static boolean hasUserAgentApi() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
-    }
-
     /**
      * Get system SmsManager
      *
@@ -68,11 +39,7 @@ class Utils {
      * @return the SmsManager for the input subId
      */
     static SmsManager getSmsManager(final int subId) {
-        if (supportMSim()) {
-            return SmsManager.getSmsManagerForSubscriptionId(subId);
-        } else {
-            return SmsManager.getDefault();
-        }
+        return SmsManager.getSmsManagerForSubscriptionId(subId);
     }
 
     /**
@@ -82,10 +49,8 @@ class Utils {
      * @return the default SMS subscription ID if the input is -1, otherwise the original
      */
     static int getEffectiveSubscriptionId(int subId) {
-        if (supportMSim()) {
-            if (subId == MmsManager.DEFAULT_SUB_ID) {
-                subId = SmsManager.getDefaultSmsSubscriptionId();
-            }
+        if (subId == MmsManager.DEFAULT_SUB_ID) {
+            subId = SmsManager.getDefaultSmsSubscriptionId();
         }
         if (subId < 0) {
             subId = MmsManager.DEFAULT_SUB_ID;
@@ -102,25 +67,11 @@ class Utils {
      */
     static int[] getMccMnc(final Context context, final int subId) {
         final int[] mccMnc = new int[] { 0, 0 };
-        if (Utils.supportMSim()) {
-            final SubscriptionManager subscriptionManager = SubscriptionManager.from(context);
-            final SubscriptionInfo subInfo = subscriptionManager.getActiveSubscriptionInfo(subId);
-            if (subInfo != null) {
-                mccMnc[0] = subInfo.getMcc();
-                mccMnc[1] = subInfo.getMnc();
-            }
-        } else {
-            final TelephonyManager telephonyManager =
-                    (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
-            final String mccMncString = telephonyManager.getSimOperator();
-            try {
-                mccMnc[0] = Integer.parseInt(mccMncString.substring(0, 3));
-                mccMnc[1] = Integer.parseInt(mccMncString.substring(3));
-            } catch (Exception e) {
-                Log.w(MmsService.TAG, "Invalid mcc/mnc from system " + mccMncString + ": " + e);
-                mccMnc[0] = 0;
-                mccMnc[1] = 0;
-            }
+        final SubscriptionManager subscriptionManager = SubscriptionManager.from(context);
+        final SubscriptionInfo subInfo = subscriptionManager.getActiveSubscriptionInfo(subId);
+        if (subInfo != null) {
+            mccMnc[0] = subInfo.getMcc();
+            mccMnc[1] = subInfo.getMnc();
         }
         return mccMnc;
     }
@@ -133,9 +84,6 @@ class Utils {
      * @return the sub-dependent Context
      */
     static Context getSubDepContext(final Context context, final int subId) {
-        if (!supportMSim()) {
-            return context;
-        }
         final int[] mccMnc = getMccMnc(context, subId);
         final int mcc = mccMnc[0];
         final int mnc = mccMnc[1];
diff --git a/src/com/android/messaging/BugleApplication.java b/src/com/android/messaging/BugleApplication.java
index d3d8a99..1b1720c 100644
--- a/src/com/android/messaging/BugleApplication.java
+++ b/src/com/android/messaging/BugleApplication.java
@@ -42,7 +42,6 @@ import com.android.messaging.util.BuglePrefs;
 import com.android.messaging.util.BuglePrefsKeys;
 import com.android.messaging.util.DebugUtils;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.Trace;
 
@@ -99,9 +98,7 @@ public class BugleApplication extends Application implements UncaughtExceptionHa
         // Fixup messages in flight if we crashed and send any pending
         dataModel.onApplicationCreated();
         // Register carrier config change receiver
-        if (OsUtil.isAtLeastM()) {
-            registerCarrierConfigChangeReceiver(context);
-        }
+        registerCarrierConfigChangeReceiver(context);
 
         Trace.endSection();
     }
diff --git a/src/com/android/messaging/FactoryImpl.java b/src/com/android/messaging/FactoryImpl.java
index a862308..5048b06 100644
--- a/src/com/android/messaging/FactoryImpl.java
+++ b/src/com/android/messaging/FactoryImpl.java
@@ -64,9 +64,6 @@ class FactoryImpl extends Factory {
     private SparseArray<BugleSubscriptionPrefs> mSubscriptionPrefs;
     private BugleCarrierConfigValuesLoader mCarrierConfigValuesLoader;
 
-    // Cached instance for Pre-L_MR1
-    private static final Object PHONEUTILS_INSTANCE_LOCK = new Object();
-    private static PhoneUtils sPhoneUtilsInstancePreLMR1 = null;
     // Cached subId->instance for L_MR1 and beyond
     private static final ConcurrentHashMap<Integer, PhoneUtils> sPhoneUtilsInstanceCacheLMR1 =
             new ConcurrentHashMap<>();
@@ -197,31 +194,19 @@ class FactoryImpl extends Factory {
 
     @Override
     public PhoneUtils getPhoneUtils(int subId) {
-        if (OsUtil.isAtLeastL_MR1()) {
-            if (subId == ParticipantData.DEFAULT_SELF_SUB_ID) {
-                subId = SmsManager.getDefaultSmsSubscriptionId();
-            }
-            if (subId < 0) {
-                LogUtil.w(LogUtil.BUGLE_TAG, "PhoneUtils.getForLMR1(): invalid subId = " + subId);
-                subId = ParticipantData.DEFAULT_SELF_SUB_ID;
-            }
-            PhoneUtils instance = sPhoneUtilsInstanceCacheLMR1.get(subId);
-            if (instance == null) {
-                instance = new PhoneUtils.PhoneUtilsLMR1(subId);
-                sPhoneUtilsInstanceCacheLMR1.putIfAbsent(subId, instance);
-            }
-            return instance;
-        } else {
-            Assert.isTrue(subId == ParticipantData.DEFAULT_SELF_SUB_ID);
-            if (sPhoneUtilsInstancePreLMR1 == null) {
-                synchronized (PHONEUTILS_INSTANCE_LOCK) {
-                    if (sPhoneUtilsInstancePreLMR1 == null) {
-                        sPhoneUtilsInstancePreLMR1 = new PhoneUtils.PhoneUtilsPreLMR1();
-                    }
-                }
-            }
-            return sPhoneUtilsInstancePreLMR1;
+        if (subId == ParticipantData.DEFAULT_SELF_SUB_ID) {
+            subId = SmsManager.getDefaultSmsSubscriptionId();
         }
+        if (subId < 0) {
+            LogUtil.w(LogUtil.BUGLE_TAG, "PhoneUtils.getForLMR1(): invalid subId = " + subId);
+            subId = ParticipantData.DEFAULT_SELF_SUB_ID;
+        }
+        PhoneUtils instance = sPhoneUtilsInstanceCacheLMR1.get(subId);
+        if (instance == null) {
+            instance = new PhoneUtils(subId);
+            sPhoneUtilsInstanceCacheLMR1.putIfAbsent(subId, instance);
+        }
+        return instance;
     }
 
     @Override
diff --git a/src/com/android/messaging/datamodel/BugleDatabaseOperations.java b/src/com/android/messaging/datamodel/BugleDatabaseOperations.java
index 4471b34..1bf9f9c 100644
--- a/src/com/android/messaging/datamodel/BugleDatabaseOperations.java
+++ b/src/com/android/messaging/datamodel/BugleDatabaseOperations.java
@@ -45,7 +45,6 @@ import com.android.messaging.util.Assert.DoesNotRunOnMainThread;
 import com.android.messaging.util.AvatarUriUtil;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.UriUtil;
 import com.android.messaging.widget.WidgetConversationProvider;
@@ -567,7 +566,7 @@ public class BugleDatabaseOperations {
         // reading and if necessary creating the conversation.
         updateConversationRow(dbWrapper, conversationId, values);
 
-        if (shouldAutoSwitchSelfId && OsUtil.isAtLeastL_MR1()) {
+        if (shouldAutoSwitchSelfId) {
             // Normally, the draft message compose UI trusts its UI state for providing up-to-date
             // conversation self id. Therefore, notify UI through local broadcast receiver about
             // this external change so the change can be properly reflected.
@@ -624,7 +623,7 @@ public class BugleDatabaseOperations {
     static boolean addSelfIdAutoSwitchInfoToContentValues(final DatabaseWrapper dbWrapper,
             final MessageData message, final String conversationId, final ContentValues values) {
         // Only auto switch conversation self for incoming messages.
-        if (!OsUtil.isAtLeastL_MR1() || !message.getIsIncoming()) {
+        if (!message.getIsIncoming()) {
             return false;
         }
 
diff --git a/src/com/android/messaging/datamodel/BugleNotifications.java b/src/com/android/messaging/datamodel/BugleNotifications.java
index 6df9e88..25e08a7 100644
--- a/src/com/android/messaging/datamodel/BugleNotifications.java
+++ b/src/com/android/messaging/datamodel/BugleNotifications.java
@@ -77,7 +77,6 @@ import com.android.messaging.util.ImageUtils;
 import com.android.messaging.util.LogUtil;
 import com.android.messaging.util.NotificationPlayer;
 import com.android.messaging.util.NotificationsUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PendingIntentConstants;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.ThreadUtil;
@@ -429,7 +428,7 @@ public class BugleNotifications {
         if (state.mParticipantAvatarsUris != null) {
             final Uri avatarUri = state.mParticipantAvatarsUris.get(0);
             final AvatarRequestDescriptor descriptor = new AvatarRequestDescriptor(avatarUri,
-                    sIconWidth, sIconHeight, OsUtil.isAtLeastL());
+                    sIconWidth, sIconHeight, true);
             final MediaRequest<ImageResource> imageRequest = descriptor.buildSyncMediaRequest(
                     context);
 
@@ -676,7 +675,6 @@ public class BugleNotifications {
 
             MediaRequest<ImageResource> imageRequest;
             if (isVideo) {
-                Assert.isTrue(VideoThumbnailRequest.shouldShowIncomingVideoThumbnails());
                 final MessagePartVideoThumbnailRequestDescriptor videoDescriptor =
                         new MessagePartVideoThumbnailRequestDescriptor(attachmentUri);
                 imageRequest = videoDescriptor.buildSyncMediaRequest(context);
diff --git a/src/com/android/messaging/datamodel/DataModelImpl.java b/src/com/android/messaging/datamodel/DataModelImpl.java
index ddb17ff..60f4152 100644
--- a/src/com/android/messaging/datamodel/DataModelImpl.java
+++ b/src/com/android/messaging/datamodel/DataModelImpl.java
@@ -54,7 +54,6 @@ import com.android.messaging.util.Assert;
 import com.android.messaging.util.Assert.DoesNotRunOnMainThread;
 import com.android.messaging.util.ConnectivityUtil;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.util.concurrent.ConcurrentHashMap;
@@ -66,8 +65,6 @@ public class DataModelImpl extends DataModel {
     private final DatabaseHelper mDatabaseHelper;
     private final SyncManager mSyncManager;
 
-    // Cached ConnectivityUtil instance for Pre-N.
-    private static ConnectivityUtil sConnectivityUtilInstanceCachePreN = null;
     // Cached ConnectivityUtil subId->instance for N and beyond
     private static final ConcurrentHashMap<Integer, ConnectivityUtil>
             sConnectivityUtilInstanceCacheN = new ConcurrentHashMap<>();
@@ -214,35 +211,27 @@ public class DataModelImpl extends DataModel {
 
     @Override
     public void onApplicationCreated() {
-        if (OsUtil.isAtLeastN()) {
-            createConnectivityUtilForEachActiveSubscription();
-        } else {
-            sConnectivityUtilInstanceCachePreN = new ConnectivityUtil(mContext);
-        }
+        createConnectivityUtilForEachActiveSubscription();
 
         FixupMessageStatusOnStartupAction.fixupMessageStatus();
         ProcessPendingMessagesAction.processFirstPendingMessage();
         SyncManager.immediateSync();
 
-        if (OsUtil.isAtLeastL_MR1()) {
-            // Start listening for subscription change events for refreshing any data associated
-            // with subscriptions.
-            PhoneUtils.getDefault().toLMr1().registerOnSubscriptionsChangedListener(
-                    new SubscriptionManager.OnSubscriptionsChangedListener() {
-                        @Override
-                        public void onSubscriptionsChanged() {
-                            // TODO: This dynamically changes the mms config that app is
-                            // currently using. It may cause inconsistency in some cases. We need
-                            // to check the usage of mms config and handle the dynamic change
-                            // gracefully
-                            MmsConfig.loadAsync();
-                            ParticipantRefresh.refreshSelfParticipants();
-                            if (OsUtil.isAtLeastN()) {
-                                createConnectivityUtilForEachActiveSubscription();
-                            }
-                        }
-                    });
-        }
+        // Start listening for subscription change events for refreshing any data associated
+        // with subscriptions.
+        PhoneUtils.getDefault().registerOnSubscriptionsChangedListener(
+                new SubscriptionManager.OnSubscriptionsChangedListener() {
+                    @Override
+                    public void onSubscriptionsChanged() {
+                        // TODO: This dynamically changes the mms config that app is
+                        // currently using. It may cause inconsistency in some cases. We need
+                        // to check the usage of mms config and handle the dynamic change
+                        // gracefully
+                        MmsConfig.loadAsync();
+                        ParticipantRefresh.refreshSelfParticipants();
+                        createConnectivityUtilForEachActiveSubscription();
+                    }
+                });
     }
 
     private void createConnectivityUtilForEachActiveSubscription() {
@@ -262,10 +251,6 @@ public class DataModelImpl extends DataModel {
     }
 
     public static ConnectivityUtil getConnectivityUtil(final int subId) {
-        if (OsUtil.isAtLeastN()) {
-            return sConnectivityUtilInstanceCacheN.get(subId);
-        } else {
-            return sConnectivityUtilInstanceCachePreN;
-        }
+        return sConnectivityUtilInstanceCacheN.get(subId);
     }
 }
diff --git a/src/com/android/messaging/datamodel/FrequentContactsCursorQueryData.java b/src/com/android/messaging/datamodel/FrequentContactsCursorQueryData.java
index d1759ad..885d1b0 100644
--- a/src/com/android/messaging/datamodel/FrequentContactsCursorQueryData.java
+++ b/src/com/android/messaging/datamodel/FrequentContactsCursorQueryData.java
@@ -25,7 +25,6 @@ import android.provider.ContactsContract.Contacts;
 import com.android.messaging.util.FallbackStrategies;
 import com.android.messaging.util.FallbackStrategies.Strategy;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 
 /**
  * Helper for querying frequent (and/or starred) contacts.
@@ -90,9 +89,7 @@ public class FrequentContactsCursorQueryData extends CursorQueryData {
                 // queries. Using strequent_phone_only query as a fallback to display only phone
                 // contacts. This is the last-ditch effort; if this fails, we will display an
                 // empty frequent list (b/18354836).
-                final String strequentQueryParam = OsUtil.isAtLeastL() ?
-                        ContactsContract.STREQUENT_PHONE_ONLY : "strequent_phone_only";
-                // TODO: Handle enterprise contacts post M once contacts provider supports it
+                final String strequentQueryParam = ContactsContract.STREQUENT_PHONE_ONLY;
                 return Contacts.CONTENT_STREQUENT_URI.buildUpon()
                         .appendQueryParameter(strequentQueryParam, "true").build();
             }
diff --git a/src/com/android/messaging/datamodel/MessageNotificationState.java b/src/com/android/messaging/datamodel/MessageNotificationState.java
index fd82f74..b30802a 100644
--- a/src/com/android/messaging/datamodel/MessageNotificationState.java
+++ b/src/com/android/messaging/datamodel/MessageNotificationState.java
@@ -519,8 +519,7 @@ public abstract class MessageNotificationState extends NotificationState {
 
             if (messageCount == 1) {
                 final boolean shouldShowImage = ContentType.isImageType(mAttachmentType)
-                        || (ContentType.isVideoType(mAttachmentType)
-                        && VideoThumbnailRequest.shouldShowIncomingVideoThumbnails());
+                        || (ContentType.isVideoType(mAttachmentType));
                 if (mAttachmentUri != null && shouldShowImage) {
                     // Show "Picture" as the content
                     final MessageLineInfo messageLineInfo = (MessageLineInfo) lineInfos.get(0);
diff --git a/src/com/android/messaging/datamodel/MessagingContentProvider.java b/src/com/android/messaging/datamodel/MessagingContentProvider.java
index b2c4a94..41bcdf7 100644
--- a/src/com/android/messaging/datamodel/MessagingContentProvider.java
+++ b/src/com/android/messaging/datamodel/MessagingContentProvider.java
@@ -36,7 +36,6 @@ import com.android.messaging.datamodel.data.ConversationMessageData;
 import com.android.messaging.datamodel.data.MessageData;
 import com.android.messaging.datamodel.data.ParticipantData;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.widget.BugleWidgetProvider;
 import com.android.messaging.widget.WidgetConversationProvider;
@@ -448,11 +447,7 @@ public class MessagingContentProvider extends ContentProvider {
         // First dump out the default SMS app package name
         String defaultSmsApp = PhoneUtils.getDefault().getDefaultSmsApp();
         if (TextUtils.isEmpty(defaultSmsApp)) {
-            if (OsUtil.isAtLeastKLP()) {
-                defaultSmsApp = "None";
-            } else {
-                defaultSmsApp = "None (pre-Kitkat)";
-            }
+            defaultSmsApp = "None";
         }
         writer.println("Default SMS app: " + defaultSmsApp);
         // Now dump logs
diff --git a/src/com/android/messaging/datamodel/ParticipantRefresh.java b/src/com/android/messaging/datamodel/ParticipantRefresh.java
index 55d439b..859a7d6 100644
--- a/src/com/android/messaging/datamodel/ParticipantRefresh.java
+++ b/src/com/android/messaging/datamodel/ParticipantRefresh.java
@@ -353,14 +353,10 @@ public class ParticipantRefresh {
      * that any other older SIM self participants are marked as inactive.
      */
     private static void refreshSelfParticipantList() {
-        if (!OsUtil.isAtLeastL_MR1()) {
-            return;
-        }
-
         final DatabaseWrapper db = DataModel.get().getDatabase();
 
         final List<SubscriptionInfo> subInfoRecords =
-                PhoneUtils.getDefault().toLMr1().getActiveSubscriptionInfoList();
+                PhoneUtils.getDefault().getActiveSubscriptionInfoList();
         final ArrayMap<Integer, SubscriptionInfo> activeSubscriptionIdToRecordMap =
                 new ArrayMap<Integer, SubscriptionInfo>();
         db.beginTransaction();
@@ -445,13 +441,11 @@ public class ParticipantRefresh {
             changed = SELF_PHONE_NUMBER_OR_SUBSCRIPTION_CHANGED;
         }
 
-        if (OsUtil.isAtLeastL_MR1()) {
-            // Refresh the subscription info based on information from SubscriptionManager.
-            final SubscriptionInfo subscriptionInfo =
-                    PhoneUtils.get(participantData.getSubId()).toLMr1().getActiveSubscriptionInfo();
-            if (participantData.updateSubscriptionInfoForSelfIfChanged(subscriptionInfo)) {
-                changed = SELF_PHONE_NUMBER_OR_SUBSCRIPTION_CHANGED;
-            }
+        // Refresh the subscription info based on information from SubscriptionManager.
+        final SubscriptionInfo subscriptionInfo =
+                PhoneUtils.get(participantData.getSubId()).getActiveSubscriptionInfo();
+        if (participantData.updateSubscriptionInfoForSelfIfChanged(subscriptionInfo)) {
+            changed = SELF_PHONE_NUMBER_OR_SUBSCRIPTION_CHANGED;
         }
 
         // For self participant, try getting name/avatar from self profile in CP2 first.
diff --git a/src/com/android/messaging/datamodel/action/InsertNewMessageAction.java b/src/com/android/messaging/datamodel/action/InsertNewMessageAction.java
index 20f90dc..b5406e4 100644
--- a/src/com/android/messaging/datamodel/action/InsertNewMessageAction.java
+++ b/src/com/android/messaging/datamodel/action/InsertNewMessageAction.java
@@ -36,7 +36,6 @@ import com.android.messaging.datamodel.data.ParticipantData;
 import com.android.messaging.sms.MmsUtils;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.util.ArrayList;
@@ -225,8 +224,7 @@ public class InsertNewMessageAction extends Action implements Parcelable {
             // to bind the message to the system default subscription if it's unbound.
             final ParticipantData unboundSelf = BugleDatabaseOperations.getExistingParticipant(
                     db, selfId);
-            if (unboundSelf.getSubId() == ParticipantData.DEFAULT_SELF_SUB_ID
-                    && OsUtil.isAtLeastL_MR1()) {
+            if (unboundSelf.getSubId() == ParticipantData.DEFAULT_SELF_SUB_ID) {
                 final int defaultSubId = PhoneUtils.getDefault().getDefaultSmsSubscriptionId();
                 self = BugleDatabaseOperations.getOrCreateSelf(db, defaultSubId);
             } else {
diff --git a/src/com/android/messaging/datamodel/action/ProcessPendingMessagesAction.java b/src/com/android/messaging/datamodel/action/ProcessPendingMessagesAction.java
index a897ce0..8d007de 100644
--- a/src/com/android/messaging/datamodel/action/ProcessPendingMessagesAction.java
+++ b/src/com/android/messaging/datamodel/action/ProcessPendingMessagesAction.java
@@ -39,7 +39,6 @@ import com.android.messaging.util.BuglePrefsKeys;
 import com.android.messaging.util.ConnectivityUtil;
 import com.android.messaging.util.ConnectivityUtil.ConnectivityListener;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.util.HashSet;
@@ -356,12 +355,10 @@ public class ProcessPendingMessagesAction extends Action implements Parcelable {
 
             // Prior to L_MR1, isActiveSubscription is true always
             boolean isActiveSubscription = true;
-            if (OsUtil.isAtLeastL_MR1()) {
-                final ParticipantData messageSelf =
-                        BugleDatabaseOperations.getExistingParticipant(db, selfId);
-                if (messageSelf == null || !messageSelf.isActiveSubscription()) {
-                    isActiveSubscription = false;
-                }
+            final ParticipantData messageSelf =
+                    BugleDatabaseOperations.getExistingParticipant(db, selfId);
+            if (messageSelf == null || !messageSelf.isActiveSubscription()) {
+                isActiveSubscription = false;
             }
             while (cursor.moveToNext()) {
                 final MessageData message = new MessageData();
diff --git a/src/com/android/messaging/datamodel/data/ConversationData.java b/src/com/android/messaging/datamodel/data/ConversationData.java
index 704e46f..2171bd1 100644
--- a/src/com/android/messaging/datamodel/data/ConversationData.java
+++ b/src/com/android/messaging/datamodel/data/ConversationData.java
@@ -51,7 +51,6 @@ import com.android.messaging.util.Assert;
 import com.android.messaging.util.Assert.RunsOnMainThread;
 import com.android.messaging.util.ContactUtil;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.SafeAsyncTask;
 import com.android.messaging.widget.WidgetConversationProvider;
@@ -595,7 +594,7 @@ public class ConversationData extends BindableData {
         Assert.isTrue(TextUtils.equals(mConversationId, message.getConversationId()));
         Assert.isTrue(binding.getData() == this);
 
-        if (!OsUtil.isAtLeastL_MR1() || message.getSelfId() == null) {
+        if (message.getSelfId() == null) {
             InsertNewMessageAction.insertNewMessage(message);
         } else {
             final int systemDefaultSubId = PhoneUtils.getDefault().getDefaultSmsSubscriptionId();
@@ -767,8 +766,7 @@ public class ConversationData extends BindableData {
         // 1. Framework has MSIM support AND
         // 2. The device has had multiple *active* subscriptions. AND
         // 3. The message's subscription is active.
-        if (OsUtil.isAtLeastL_MR1() &&
-                selfParticipantsData.getSelfParticipantsCountExcludingDefault(true) > 1) {
+        if (selfParticipantsData.getSelfParticipantsCountExcludingDefault(true) > 1) {
             return subscriptionListData.getActiveSubscriptionEntryBySelfId(selfParticipantId,
                     excludeDefault);
         }
diff --git a/src/com/android/messaging/datamodel/data/SelfParticipantsData.java b/src/com/android/messaging/datamodel/data/SelfParticipantsData.java
index f389a78..cc27642 100644
--- a/src/com/android/messaging/datamodel/data/SelfParticipantsData.java
+++ b/src/com/android/messaging/datamodel/data/SelfParticipantsData.java
@@ -24,8 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
-import com.android.messaging.util.OsUtil;
-
 /**
  * A class that contains the list of all self participants potentially involved in a conversation.
  * This class contains both active/inactive self entries when there is multi-SIM support.
@@ -86,9 +84,6 @@ public class SelfParticipantsData {
      * Returns if a given self id represents the default self.
      */
     boolean isDefaultSelf(final String selfId) {
-        if (!OsUtil.isAtLeastL_MR1()) {
-            return true;
-        }
         final ParticipantData self = getSelfParticipantById(selfId);
         return self == null ? false : self.getSubId() == ParticipantData.DEFAULT_SELF_SUB_ID;
     }
diff --git a/src/com/android/messaging/datamodel/data/SettingsData.java b/src/com/android/messaging/datamodel/data/SettingsData.java
index 7474619..07b9451 100644
--- a/src/com/android/messaging/datamodel/data/SettingsData.java
+++ b/src/com/android/messaging/datamodel/data/SettingsData.java
@@ -31,7 +31,6 @@ import com.android.messaging.datamodel.binding.BindableData;
 import com.android.messaging.datamodel.binding.BindingBase;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -200,7 +199,7 @@ public class SettingsData extends BindableData implements
         // platorm is at least L-MR1 and there are multiple active SIMs.
         final int activeSubCountExcludingDefault =
                 mSelfParticipantsData.getSelfParticipantsCountExcludingDefault(true);
-        if (OsUtil.isAtLeastL_MR1() && activeSubCountExcludingDefault > 0) {
+        if (activeSubCountExcludingDefault > 0) {
             for (ParticipantData self : selfs) {
                 if (!self.isDefaultSelf()) {
                     if (activeSubCountExcludingDefault > 1) {
diff --git a/src/com/android/messaging/datamodel/media/DecodedImageResource.java b/src/com/android/messaging/datamodel/media/DecodedImageResource.java
index 3627ba4..f5f9112 100644
--- a/src/com/android/messaging/datamodel/media/DecodedImageResource.java
+++ b/src/com/android/messaging/datamodel/media/DecodedImageResource.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +25,6 @@ import com.android.messaging.util.Assert;
 import com.android.messaging.util.Assert.DoesNotRunOnMainThread;
 import com.android.messaging.util.ImageUtils;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 
 import java.util.List;
 
@@ -109,11 +109,7 @@ public class DecodedImageResource extends ImageResource {
         acquireLock();
         try {
             Assert.notNull(mBitmap);
-            if (OsUtil.isAtLeastKLP()) {
-                return mBitmap.getAllocationByteCount();
-            } else {
-                return mBitmap.getRowBytes() * mBitmap.getHeight();
-            }
+            return mBitmap.getAllocationByteCount();
         } finally {
             releaseLock();
         }
diff --git a/src/com/android/messaging/datamodel/media/VideoThumbnailRequest.java b/src/com/android/messaging/datamodel/media/VideoThumbnailRequest.java
index 73ce5e0..53eebb2 100644
--- a/src/com/android/messaging/datamodel/media/VideoThumbnailRequest.java
+++ b/src/com/android/messaging/datamodel/media/VideoThumbnailRequest.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +21,6 @@ import android.content.Context;
 import android.graphics.Bitmap;
 
 import com.android.messaging.util.MediaMetadataRetrieverWrapper;
-import com.android.messaging.util.MediaUtil;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
@@ -28,7 +28,6 @@ import java.io.InputStream;
 
 /**
  * Class to request a video thumbnail.
- * Users of this class as responsible for checking {@link #shouldShowIncomingVideoThumbnails}
  */
 public class VideoThumbnailRequest extends ImageRequest<UriImageRequestDescriptor> {
 
@@ -37,10 +36,6 @@ public class VideoThumbnailRequest extends ImageRequest<UriImageRequestDescripto
         super(context, descriptor);
     }
 
-    public static boolean shouldShowIncomingVideoThumbnails() {
-        return MediaUtil.canAutoAccessIncomingMedia();
-    }
-
     @Override
     protected InputStream getInputStreamForResource() throws FileNotFoundException {
         return null;
diff --git a/src/com/android/messaging/mmslib/pdu/PduPersister.java b/src/com/android/messaging/mmslib/pdu/PduPersister.java
index ffa37bb..9b2dc12 100644
--- a/src/com/android/messaging/mmslib/pdu/PduPersister.java
+++ b/src/com/android/messaging/mmslib/pdu/PduPersister.java
@@ -39,7 +39,6 @@ import android.util.Log;
 import android.util.SparseArray;
 import android.util.SparseIntArray;
 
-import com.android.messaging.datamodel.data.ParticipantData;
 import com.android.messaging.mmslib.InvalidHeaderValueException;
 import com.android.messaging.mmslib.MmsException;
 import com.android.messaging.mmslib.SqliteWrapper;
@@ -51,7 +50,6 @@ import com.android.messaging.sms.MmsSmsUtils;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.UriUtil;
 
 import java.io.ByteArrayOutputStream;
@@ -1481,15 +1479,8 @@ public class PduPersister {
         }
         // Record whether this mms message is a simple plain text or not. This is a hint for the
         // UI.
-        if (OsUtil.isAtLeastJB_MR1()) {
-            values.put(Mms.TEXT_ONLY, textOnly ? 1 : 0);
-        }
-
-        if (OsUtil.isAtLeastL_MR1()) {
-            values.put(Mms.SUBSCRIPTION_ID, subId);
-        } else {
-            Assert.equals(ParticipantData.DEFAULT_SELF_SUB_ID, subId);
-        }
+        values.put(Mms.TEXT_ONLY, textOnly ? 1 : 0);
+        values.put(Mms.SUBSCRIPTION_ID, subId);
 
         Uri res = null;
         if (existingUri) {
diff --git a/src/com/android/messaging/receiver/AbortMmsWapPushReceiver.java b/src/com/android/messaging/receiver/AbortMmsWapPushReceiver.java
deleted file mode 100644
index 9e09a2a..0000000
--- a/src/com/android/messaging/receiver/AbortMmsWapPushReceiver.java
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright (C) 2015 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.messaging.receiver;
-
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.provider.Telephony;
-
-import com.android.messaging.util.ContentType;
-import com.android.messaging.util.OsUtil;
-import com.android.messaging.util.PhoneUtils;
-
-/**
- * This receiver is used to abort MMS WAP broadcasts pre-KLP when SMS is enabled.
- */
-public class AbortMmsWapPushReceiver extends BroadcastReceiver {
-    @Override
-    public void onReceive(final Context context, final Intent intent) {
-        if (Telephony.Sms.Intents.WAP_PUSH_RECEIVED_ACTION.equals(intent.getAction())
-                && ContentType.MMS_MESSAGE.equals(intent.getType())) {
-            // If we are enabled, it's our job to stop the broadcast from continuing. This
-            // receiver is not used on KLP but we do an extra check here just to make sure.
-            if (!OsUtil.isAtLeastKLP() && PhoneUtils.getDefault().isSmsEnabled()) {
-                abortBroadcast();
-            }
-        }
-    }
-}
diff --git a/src/com/android/messaging/receiver/AbortSmsReceiver.java b/src/com/android/messaging/receiver/AbortSmsReceiver.java
deleted file mode 100644
index f4491d8..0000000
--- a/src/com/android/messaging/receiver/AbortSmsReceiver.java
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * Copyright (C) 2015 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.messaging.receiver;
-
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-
-import com.android.messaging.util.OsUtil;
-import com.android.messaging.util.PhoneUtils;
-
-/**
- * This receiver is used to abort SMS broadcasts pre-KLP when SMS is enabled.
- */
-public final class AbortSmsReceiver extends BroadcastReceiver {
-
-    @Override
-    public void onReceive(final Context context, final Intent intent) {
-        // If we are enabled, it's our job to stop the broadcast from continuing. This
-        // receiver is not used on KLP but we do an extra check here just to make sure.
-        if (!OsUtil.isAtLeastKLP() && PhoneUtils.getDefault().isSmsEnabled()) {
-            if (!SmsReceiver.shouldIgnoreMessage(intent)) {
-                abortBroadcast();
-            }
-        }
-    }
-}
diff --git a/src/com/android/messaging/receiver/MmsWapPushDeliverReceiver.java b/src/com/android/messaging/receiver/MmsWapPushDeliverReceiver.java
index a5c247c..73bdceb 100644
--- a/src/com/android/messaging/receiver/MmsWapPushDeliverReceiver.java
+++ b/src/com/android/messaging/receiver/MmsWapPushDeliverReceiver.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +22,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.provider.Telephony;
 
+import com.android.messaging.datamodel.action.ReceiveMmsMessageAction;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.PhoneUtils;
 
@@ -29,15 +31,27 @@ import com.android.messaging.util.PhoneUtils;
  */
 public class MmsWapPushDeliverReceiver extends BroadcastReceiver {
 
+    static final String EXTRA_SUBSCRIPTION = "subscription";
+    static final String EXTRA_DATA = "data";
+
     @Override
     public void onReceive(final Context context, final Intent intent) {
         if (Telephony.Sms.Intents.WAP_PUSH_DELIVER_ACTION.equals(intent.getAction())
                 && ContentType.MMS_MESSAGE.equals(intent.getType())) {
             // Always convert negative subIds into -1
             int subId = PhoneUtils.getDefault().getEffectiveIncomingSubIdFromSystem(
-                    intent, MmsWapPushReceiver.EXTRA_SUBSCRIPTION);
-            byte[] data = intent.getByteArrayExtra(MmsWapPushReceiver.EXTRA_DATA);
-            MmsWapPushReceiver.mmsReceived(subId, data);
+                    intent, EXTRA_SUBSCRIPTION);
+            byte[] data = intent.getByteArrayExtra(EXTRA_DATA);
+            mmsReceived(subId, data);
         }
     }
+
+    static void mmsReceived(final int subId, final byte[] data) {
+        if (!PhoneUtils.getDefault().isSmsEnabled()) {
+            return;
+        }
+
+        final ReceiveMmsMessageAction action = new ReceiveMmsMessageAction(subId, data);
+        action.start();
+    }
 }
diff --git a/src/com/android/messaging/receiver/MmsWapPushReceiver.java b/src/com/android/messaging/receiver/MmsWapPushReceiver.java
deleted file mode 100644
index 29cf0db..0000000
--- a/src/com/android/messaging/receiver/MmsWapPushReceiver.java
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * Copyright (C) 2015 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.messaging.receiver;
-
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.provider.Telephony;
-
-import com.android.messaging.datamodel.action.ReceiveMmsMessageAction;
-import com.android.messaging.util.ContentType;
-import com.android.messaging.util.PhoneUtils;
-
-/**
- * Class that handles MMS WAP push intent from telephony on pre-KLP Devices.
- */
-public class MmsWapPushReceiver extends BroadcastReceiver {
-    static final String EXTRA_SUBSCRIPTION = "subscription";
-    static final String EXTRA_DATA = "data";
-
-    @Override
-    public void onReceive(final Context context, final Intent intent) {
-        if (Telephony.Sms.Intents.WAP_PUSH_RECEIVED_ACTION.equals(intent.getAction())
-                && ContentType.MMS_MESSAGE.equals(intent.getType())) {
-            if (PhoneUtils.getDefault().isSmsEnabled()) {
-                // Always convert negative subIds into -1
-                final int subId = PhoneUtils.getDefault().getEffectiveIncomingSubIdFromSystem(
-                        intent, MmsWapPushReceiver.EXTRA_SUBSCRIPTION);
-                final byte[] data = intent.getByteArrayExtra(MmsWapPushReceiver.EXTRA_DATA);
-                mmsReceived(subId, data);
-            }
-        }
-    }
-
-    static void mmsReceived(final int subId, final byte[] data) {
-        if (!PhoneUtils.getDefault().isSmsEnabled()) {
-            return;
-        }
-
-        final ReceiveMmsMessageAction action = new ReceiveMmsMessageAction(subId, data);
-        action.start();
-    }
-}
-
diff --git a/src/com/android/messaging/receiver/SmsReceiver.java b/src/com/android/messaging/receiver/SmsReceiver.java
index 89a3710..c3a5d98 100644
--- a/src/com/android/messaging/receiver/SmsReceiver.java
+++ b/src/com/android/messaging/receiver/SmsReceiver.java
@@ -73,36 +73,12 @@ public final class SmsReceiver extends BroadcastReceiver {
      * notification.
      */
     public static void updateSmsReceiveHandler(final Context context) {
-        boolean smsReceiverEnabled;
-        boolean mmsWapPushReceiverEnabled;
-        boolean respondViaMessageEnabled;
-        boolean broadcastAbortEnabled;
-
-        if (OsUtil.isAtLeastKLP()) {
-            // When we're running as the secondary user, we don't get the new SMS_DELIVER intent,
-            // only the primary user receives that. As secondary, we need to go old-school and
-            // listen for the SMS_RECEIVED intent. For the secondary user, use this SmsReceiver
-            // for both sms and mms notification. For the primary user on KLP (and above), we don't
-            // use the SmsReceiver.
-            smsReceiverEnabled = OsUtil.isSecondaryUser();
-            // On KLP use the new deliver event for mms
-            mmsWapPushReceiverEnabled = false;
-            // On KLP we need to always enable this handler to show in the list of sms apps
-            respondViaMessageEnabled = true;
-            // On KLP we don't need to abort the broadcast
-            broadcastAbortEnabled = false;
-        } else {
-            // On JB we use the sms receiver for both sms/mms delivery
-            final boolean carrierSmsEnabled = PhoneUtils.getDefault().isSmsEnabled();
-            smsReceiverEnabled = carrierSmsEnabled;
-
-            // On JB we use the mms receiver when sms/mms is enabled
-            mmsWapPushReceiverEnabled = carrierSmsEnabled;
-            // On JB this is dynamic to make sure we don't show in dialer if sms is disabled
-            respondViaMessageEnabled = carrierSmsEnabled;
-            // On JB we need to abort broadcasts if SMS is enabled
-            broadcastAbortEnabled = carrierSmsEnabled;
-        }
+        // When we're running as the secondary user, we don't get the new SMS_DELIVER intent,
+        // only the primary user receives that. As secondary, we need to go old-school and
+        // listen for the SMS_RECEIVED intent. For the secondary user, use this SmsReceiver
+        // for both sms and mms notification. For the primary user on KLP (and above), we don't
+        // use the SmsReceiver.
+        boolean smsReceiverEnabled = OsUtil.isSecondaryUser();
 
         final PackageManager packageManager = context.getPackageManager();
         final boolean logv = LogUtil.isLoggable(TAG, LogUtil.VERBOSE);
@@ -122,57 +98,13 @@ public final class SmsReceiver extends BroadcastReceiver {
                     new ComponentName(context, SmsReceiver.class),
                     PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
         }
-        if (mmsWapPushReceiverEnabled) {
-            if (logv) {
-                LogUtil.v(TAG, "Enabling MMS message receiving");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, MmsWapPushReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
-        } else {
-            if (logv) {
-                LogUtil.v(TAG, "Disabling MMS message receiving");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, MmsWapPushReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
-        }
-        if (broadcastAbortEnabled) {
-            if (logv) {
-                LogUtil.v(TAG, "Enabling SMS/MMS broadcast abort");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, AbortSmsReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, AbortMmsWapPushReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
-        } else {
-            if (logv) {
-                LogUtil.v(TAG, "Disabling SMS/MMS broadcast abort");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, AbortSmsReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, AbortMmsWapPushReceiver.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
-        }
-        if (respondViaMessageEnabled) {
-            if (logv) {
-                LogUtil.v(TAG, "Enabling respond via message intent");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, NoConfirmationSmsSendService.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
-        } else {
-            if (logv) {
-                LogUtil.v(TAG, "Disabling respond via message intent");
-            }
-            packageManager.setComponentEnabledSetting(
-                    new ComponentName(context, NoConfirmationSmsSendService.class),
-                    PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
+        if (logv) {
+            LogUtil.v(TAG, "Enabling respond via message intent");
         }
+        packageManager.setComponentEnabledSetting(
+                new ComponentName(context, NoConfirmationSmsSendService.class),
+                PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
+
     }
 
     private static final String EXTRA_ERROR_CODE = "errorCode";
@@ -214,9 +146,7 @@ public final class SmsReceiver extends BroadcastReceiver {
         // seen for the telephony db.
         messageValues.put(Sms.Inbox.READ, 0);
         messageValues.put(Sms.Inbox.SEEN, 0);
-        if (OsUtil.isAtLeastL_MR1()) {
-            messageValues.put(Sms.SUBSCRIPTION_ID, subId);
-        }
+        messageValues.put(Sms.SUBSCRIPTION_ID, subId);
 
         if (messages[0].getMessageClass() == android.telephony.SmsMessage.MessageClass.CLASS_0 ||
                 DebugUtils.debugClassZeroSmsEnabled()) {
@@ -238,8 +168,6 @@ public final class SmsReceiver extends BroadcastReceiver {
                             // TODO: update this with the actual constant from Telephony
                             "android.provider.Telephony.MMS_DOWNLOADED".equals(action))) {
                 postNewMessageSecondaryUserNotification();
-            } else if (!OsUtil.isAtLeastKLP()) {
-                deliverSmsIntent(context, intent);
             }
         }
     }
diff --git a/src/com/android/messaging/sms/BugleApnSettingsLoader.java b/src/com/android/messaging/sms/BugleApnSettingsLoader.java
index d3bb82c..1305a3a 100644
--- a/src/com/android/messaging/sms/BugleApnSettingsLoader.java
+++ b/src/com/android/messaging/sms/BugleApnSettingsLoader.java
@@ -34,7 +34,6 @@ import com.android.messaging.mmslib.SqliteWrapper;
 import com.android.messaging.util.BugleGservices;
 import com.android.messaging.util.BugleGservicesKeys;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.net.URI;
@@ -384,7 +383,7 @@ public class BugleApnSettingsLoader implements ApnSettingsLoader {
      */
     private void loadFromSystem(final int subId, final String apnName, final List<Apn> apns) {
         Uri uri;
-        if (OsUtil.isAtLeastL_MR1() && subId != MmsManager.DEFAULT_SUB_ID) {
+        if (subId != MmsManager.DEFAULT_SUB_ID) {
             uri = Uri.withAppendedPath(Telephony.Carriers.CONTENT_URI, "/subId/" + subId);
         } else {
             uri = Telephony.Carriers.CONTENT_URI;
diff --git a/src/com/android/messaging/sms/BugleCarrierConfigValuesLoader.java b/src/com/android/messaging/sms/BugleCarrierConfigValuesLoader.java
index 6ad9201..ad3efee 100644
--- a/src/com/android/messaging/sms/BugleCarrierConfigValuesLoader.java
+++ b/src/com/android/messaging/sms/BugleCarrierConfigValuesLoader.java
@@ -27,7 +27,6 @@ import android.util.SparseArray;
 
 import com.android.messaging.R;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 /**
@@ -93,12 +92,9 @@ public class BugleCarrierConfigValuesLoader implements CarrierConfigValuesLoader
     private String loadLocked(final int subId, final Bundle values) {
         // Load from resources in earlier platform
         loadFromResources(subId, values);
-        if (OsUtil.isAtLeastL()) {
-            // Load from system to override if system API exists
-            loadFromSystem(subId, values);
-            return "resources+system";
-        }
-        return "resources";
+        // Load from system to override if system API exists
+        loadFromSystem(subId, values);
+        return "resources+system";
     }
 
     /**
@@ -158,9 +154,6 @@ public class BugleCarrierConfigValuesLoader implements CarrierConfigValuesLoader
      * @return the sub-dependent Context
      */
     private static Context getSubDepContext(final Context context, final int subId) {
-        if (!OsUtil.isAtLeastL_MR1()) {
-            return context;
-        }
         final int[] mccMnc = PhoneUtils.get(subId).getMccMnc();
         final int mcc = mccMnc[0];
         final int mnc = mccMnc[1];
diff --git a/src/com/android/messaging/sms/BugleUserAgentInfoLoader.java b/src/com/android/messaging/sms/BugleUserAgentInfoLoader.java
index 9612934..cce12b0 100644
--- a/src/com/android/messaging/sms/BugleUserAgentInfoLoader.java
+++ b/src/com/android/messaging/sms/BugleUserAgentInfoLoader.java
@@ -25,7 +25,6 @@ import android.text.TextUtils;
 import com.android.messaging.util.BugleGservices;
 import com.android.messaging.util.BugleGservicesKeys;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.VersionUtil;
 
 /**
@@ -75,13 +74,11 @@ public class BugleUserAgentInfoLoader implements UserAgentInfoLoader {
     }
 
     private void loadLocked() {
-        if (OsUtil.isAtLeastKLP()) {
-            // load the MMS User agent and UaProfUrl from TelephonyManager APIs
-            final TelephonyManager telephonyManager = (TelephonyManager) mContext.getSystemService(
-                    Context.TELEPHONY_SERVICE);
-            mUserAgent = telephonyManager.getMmsUserAgent();
-            mUAProfUrl = telephonyManager.getMmsUAProfUrl();
-        }
+        // load the MMS User agent and UaProfUrl from TelephonyManager APIs
+        final TelephonyManager telephonyManager = (TelephonyManager) mContext.getSystemService(
+                Context.TELEPHONY_SERVICE);
+        mUserAgent = telephonyManager.getMmsUserAgent();
+        mUAProfUrl = telephonyManager.getMmsUAProfUrl();
         // if user agent string isn't set, use the format "Bugle/<app_version>".
         if (TextUtils.isEmpty(mUserAgent)) {
             final String simpleVersionName = VersionUtil.getInstance(mContext).getSimpleName();
diff --git a/src/com/android/messaging/sms/DatabaseMessages.java b/src/com/android/messaging/sms/DatabaseMessages.java
index 0f662e5..36bdefe 100644
--- a/src/com/android/messaging/sms/DatabaseMessages.java
+++ b/src/com/android/messaging/sms/DatabaseMessages.java
@@ -37,11 +37,9 @@ import com.android.messaging.Factory;
 import com.android.messaging.datamodel.data.MessageData;
 import com.android.messaging.datamodel.media.VideoThumbnailRequest;
 import com.android.messaging.mmslib.pdu.CharacterSets;
-import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
 import com.android.messaging.util.MediaMetadataRetrieverWrapper;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.google.common.collect.Lists;
 
@@ -120,12 +118,6 @@ public class DatabaseMessages {
                 if (!MmsUtils.hasSmsDateSentColumn()) {
                     projection[INDEX_DATE_SENT] = Sms.DATE;
                 }
-                if (!OsUtil.isAtLeastL_MR1()) {
-                    Assert.equals(INDEX_SUB_ID, projection.length - 1);
-                    String[] withoutSubId = new String[projection.length - 1];
-                    System.arraycopy(projection, 0, withoutSubId, 0, withoutSubId.length);
-                    projection = withoutSubId;
-                }
 
                 sProjection = projection;
             }
@@ -307,13 +299,6 @@ public class DatabaseMessages {
                     Mms.SUBSCRIPTION_ID,
                 };
 
-                if (!OsUtil.isAtLeastL_MR1()) {
-                    Assert.equals(INDEX_SUB_ID, projection.length - 1);
-                    String[] withoutSubId = new String[projection.length - 1];
-                    System.arraycopy(projection, 0, withoutSubId, 0, withoutSubId.length);
-                    projection = withoutSubId;
-                }
-
                 sProjection = projection;
             }
 
@@ -722,11 +707,6 @@ public class DatabaseMessages {
          * Load video file of a video part and parse the dimensions and type
          */
         private void loadVideo() {
-            // This is a coarse check, and should not be applied to outgoing messages. However,
-            // currently, this does not cause any problems.
-            if (!VideoThumbnailRequest.shouldShowIncomingVideoThumbnails()) {
-                return;
-            }
             final Uri uri = getDataUri();
             final MediaMetadataRetrieverWrapper retriever = new MediaMetadataRetrieverWrapper();
             try {
diff --git a/src/com/android/messaging/sms/MmsConfig.java b/src/com/android/messaging/sms/MmsConfig.java
index 6cb7ca5..8651697 100644
--- a/src/com/android/messaging/sms/MmsConfig.java
+++ b/src/com/android/messaging/sms/MmsConfig.java
@@ -25,7 +25,6 @@ import com.android.messaging.Factory;
 import com.android.messaging.datamodel.data.ParticipantData;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.SafeAsyncTask;
 import com.google.common.collect.Maps;
@@ -151,27 +150,21 @@ public class MmsConfig {
         // Rebuild the entire MmsConfig map.
         sSubIdToMmsConfigMap.clear();
         loader.reset();
-        if (OsUtil.isAtLeastL_MR1()) {
-            final List<SubscriptionInfo> subInfoRecords =
-                    PhoneUtils.getDefault().toLMr1().getActiveSubscriptionInfoList();
-            if (subInfoRecords == null) {
-                LogUtil.w(TAG, "Loading mms config failed: no active SIM");
-                return;
-            }
-            for (SubscriptionInfo subInfoRecord : subInfoRecords) {
-                final int subId = subInfoRecord.getSubscriptionId();
-                final Bundle values = loader.get(subId);
-                addMmsConfig(new MmsConfig(subId, values));
-            }
-        } else {
-            final Bundle values = loader.get(ParticipantData.DEFAULT_SELF_SUB_ID);
-            addMmsConfig(new MmsConfig(ParticipantData.DEFAULT_SELF_SUB_ID, values));
+        final List<SubscriptionInfo> subInfoRecords =
+                PhoneUtils.getDefault().getActiveSubscriptionInfoList();
+        if (subInfoRecords == null) {
+            LogUtil.w(TAG, "Loading mms config failed: no active SIM");
+            return;
+        }
+        for (SubscriptionInfo subInfoRecord : subInfoRecords) {
+            final int subId = subInfoRecord.getSubscriptionId();
+            final Bundle values = loader.get(subId);
+            addMmsConfig(new MmsConfig(subId, values));
         }
     }
 
     private static void addMmsConfig(MmsConfig mmsConfig) {
-        Assert.isTrue(OsUtil.isAtLeastL_MR1() !=
-                (mmsConfig.mSubId == ParticipantData.DEFAULT_SELF_SUB_ID));
+        Assert.isTrue(mmsConfig.mSubId != ParticipantData.DEFAULT_SELF_SUB_ID);
         sSubIdToMmsConfigMap.put(mmsConfig.mSubId, mmsConfig);
     }
 
diff --git a/src/com/android/messaging/sms/MmsUtils.java b/src/com/android/messaging/sms/MmsUtils.java
index 32f0616..f84b80a 100644
--- a/src/com/android/messaging/sms/MmsUtils.java
+++ b/src/com/android/messaging/sms/MmsUtils.java
@@ -76,7 +76,6 @@ import com.android.messaging.util.ImageUtils;
 import com.android.messaging.util.ImageUtils.ImageResizer;
 import com.android.messaging.util.LogUtil;
 import com.android.messaging.util.MediaMetadataRetrieverWrapper;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.google.common.base.Joiner;
 
@@ -869,9 +868,7 @@ public class MmsUtils {
         values.put(Telephony.Sms.SEEN, seen ? 1 : 0);
         values.put(Telephony.Sms.SUBJECT, subject);
         values.put(Telephony.Sms.BODY, body);
-        if (OsUtil.isAtLeastL_MR1()) {
-            values.put(Telephony.Sms.SUBSCRIPTION_ID, subId);
-        }
+        values.put(Telephony.Sms.SUBSCRIPTION_ID, subId);
         if (status != Telephony.Sms.STATUS_NONE) {
             values.put(Telephony.Sms.STATUS, status);
         }
@@ -1156,9 +1153,7 @@ public class MmsUtils {
     public static SmsMessage getSmsMessageFromDeliveryReport(final Intent intent) {
         final byte[] pdu = intent.getByteArrayExtra("pdu");
         final String format = intent.getStringExtra("format");
-        return OsUtil.isAtLeastM()
-                ? SmsMessage.createFromPdu(pdu, format)
-                : SmsMessage.createFromPdu(pdu);
+        return SmsMessage.createFromPdu(pdu, format);
     }
 
     /**
@@ -1520,27 +1515,22 @@ public class MmsUtils {
     // For the internal debugger only
     public static void setUseSystemApnTable(final boolean turnOn) {
         if (!turnOn) {
-            // We're not turning on to the system table. Instead, we're using our internal table.
-            final int osVersion = OsUtil.getApiVersion();
-            if (osVersion != android.os.Build.VERSION_CODES.JELLY_BEAN_MR1) {
-                // We're turning on local APNs on a device where we wouldn't normally have the
-                // local APN table. Build it here.
+            // We're turning on local APNs on a device where we wouldn't normally have the
+            // local APN table. Build it here.
+            final SQLiteDatabase database = ApnDatabase.getApnDatabase().getWritableDatabase();
 
-                final SQLiteDatabase database = ApnDatabase.getApnDatabase().getWritableDatabase();
-
-                // Do we already have the table?
-                Cursor cursor = null;
-                try {
-                    cursor = database.query(ApnDatabase.APN_TABLE,
-                            ApnDatabase.APN_PROJECTION,
-                            null, null, null, null, null, null);
-                } catch (final Exception e) {
-                    // Apparently there's no table, create it now.
-                    ApnDatabase.forceBuildAndLoadApnTables();
-                } finally {
-                    if (cursor != null) {
-                        cursor.close();
-                    }
+            // Do we already have the table?
+            Cursor cursor = null;
+            try {
+                cursor = database.query(ApnDatabase.APN_TABLE,
+                        ApnDatabase.APN_PROJECTION,
+                        null, null, null, null, null, null);
+            } catch (final Exception e) {
+                // Apparently there's no table, create it now.
+                ApnDatabase.forceBuildAndLoadApnTables();
+            } finally {
+                if (cursor != null) {
+                    cursor.close();
                 }
             }
         }
@@ -1812,14 +1802,6 @@ public class MmsUtils {
             return new StatusPlusUri(
                     MMS_REQUEST_NO_RETRY, MessageData.RAW_TELEPHONY_STATUS_UNDEFINED, null);
         }
-        if (!isMmsDataAvailable(subId)) {
-            LogUtil.e(TAG,
-                    "MmsUtils: failed to download message, no data available");
-            return new StatusPlusUri(MMS_REQUEST_MANUAL_RETRY,
-                    MessageData.RAW_TELEPHONY_STATUS_UNDEFINED,
-                    null,
-                    SmsManager.MMS_ERROR_NO_DATA_NETWORK);
-        }
         int status = MMS_REQUEST_MANUAL_RETRY;
         try {
             RetrieveConf retrieveConf = null;
@@ -1837,14 +1819,10 @@ public class MmsUtils {
                     LogUtil.d(TAG, "MmsUtils: Downloading MMS via MMS lib API; notification "
                             + "message: " + notificationUri);
                 }
-                if (OsUtil.isAtLeastL_MR1()) {
-                    if (subId < 0) {
-                        LogUtil.e(TAG, "MmsUtils: Incoming MMS came from unknown SIM");
-                        throw new MmsFailureException(MMS_REQUEST_NO_RETRY,
-                                "Message from unknown SIM");
-                    }
-                } else {
-                    Assert.isTrue(subId == ParticipantData.DEFAULT_SELF_SUB_ID);
+                if (subId < 0) {
+                    LogUtil.e(TAG, "MmsUtils: Incoming MMS came from unknown SIM");
+                    throw new MmsFailureException(MMS_REQUEST_NO_RETRY,
+                            "Message from unknown SIM");
                 }
                 if (extras == null) {
                     extras = new Bundle();
@@ -1943,10 +1921,6 @@ public class MmsUtils {
                 LogUtil.w(TAG, "MmsUtils: Can't send NotifyResp; transaction id is null");
                 return;
             }
-            if (!isMmsDataAvailable(subId)) {
-                LogUtil.w(TAG, "MmsUtils: Can't send NotifyResp; no data available");
-                return;
-            }
             MmsSender.sendNotifyResponseForMmsDownload(
                     context, subId, transactionId, contentLocation, status);
         } catch (final MmsFailureException e) {
@@ -1973,10 +1947,6 @@ public class MmsUtils {
                 LogUtil.w(TAG, "MmsUtils: Can't send AckInd; transaction id is null");
                 return;
             }
-            if (!isMmsDataAvailable(subId)) {
-                LogUtil.w(TAG, "MmsUtils: Can't send AckInd; no data available");
-                return;
-            }
             MmsSender.sendAcknowledgeForMmsDownload(context, subId, transactionId, contentLocation);
         } catch (final MmsFailureException e) {
             LogUtil.e(TAG, "sendAcknowledgeForMmsDownload: failed to retrieve message " + e, e);
@@ -2021,35 +1991,10 @@ public class MmsUtils {
         return (RetrieveConf) pdu;
     }
 
-    private static boolean isMmsDataAvailable(final int subId) {
-        if (OsUtil.isAtLeastL_MR1()) {
-            // L_MR1 above may support sending mms via wifi
-            return true;
-        }
-        final PhoneUtils phoneUtils = PhoneUtils.get(subId);
-        return !phoneUtils.isAirplaneModeOn() && phoneUtils.isMobileDataEnabled();
-    }
-
-    private static boolean isSmsDataAvailable(final int subId) {
-        if (OsUtil.isAtLeastL_MR1()) {
-            // L_MR1 above may support sending sms via wifi
-            return true;
-        }
-        final PhoneUtils phoneUtils = PhoneUtils.get(subId);
-        return !phoneUtils.isAirplaneModeOn();
-    }
-
     public static StatusPlusUri sendMmsMessage(final Context context, final int subId,
             final Uri messageUri, final Bundle extras) {
         int status = MMS_REQUEST_MANUAL_RETRY;
         int rawStatus = MessageData.RAW_TELEPHONY_STATUS_UNDEFINED;
-        if (!isMmsDataAvailable(subId)) {
-            LogUtil.w(TAG, "MmsUtils: failed to send message, no data available");
-            return new StatusPlusUri(MMS_REQUEST_MANUAL_RETRY,
-                    MessageData.RAW_TELEPHONY_STATUS_UNDEFINED,
-                    messageUri,
-                    SmsManager.MMS_ERROR_NO_DATA_NETWORK);
-        }
         final PduPersister persister = PduPersister.getPduPersister(context);
         try {
             final SendReq sendReq = (SendReq) persister.load(messageUri);
@@ -2460,10 +2405,6 @@ public class MmsUtils {
     public static int sendSmsMessage(final String recipient, final String messageText,
             final Uri requestUri, final int subId,
             final String smsServiceCenter, final boolean requireDeliveryReport) {
-        if (!isSmsDataAvailable(subId)) {
-            LogUtil.w(TAG, "MmsUtils: can't send SMS without radio");
-            return MMS_REQUEST_MANUAL_RETRY;
-        }
         final Context context = Factory.get().getApplicationContext();
         int status = MMS_REQUEST_MANUAL_RETRY;
         try {
diff --git a/src/com/android/messaging/ui/AudioAttachmentView.java b/src/com/android/messaging/ui/AudioAttachmentView.java
index ad91ed2..fec26a8 100644
--- a/src/com/android/messaging/ui/AudioAttachmentView.java
+++ b/src/com/android/messaging/ui/AudioAttachmentView.java
@@ -41,7 +41,6 @@ import com.android.messaging.ui.mediapicker.PausableChronometer;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.MediaUtil;
 import com.android.messaging.util.UiUtils;
 
 /**
@@ -79,9 +78,6 @@ public class AudioAttachmentView extends LinearLayout {
     private int mThemeColor;
 
     private boolean mStartPlayAfterPrepare;
-    // should the MediaPlayer be prepared lazily when the user chooses to play the audio (as
-    // opposed to preparing it early, on bind)
-    private boolean mPrepareOnPlayback;
     private boolean mPrepared;
     private boolean mPlaybackFinished; // Was the audio played all the way to the end
     private final int mMode;
@@ -148,12 +144,7 @@ public class AudioAttachmentView extends LinearLayout {
             return;
         }
 
-        if (mPrepareOnPlayback) {
-            // For lazy preparation, the chronometer will only be shown during playback
-            mChronometer.setVisibility(playing ? View.VISIBLE : View.INVISIBLE);
-        } else {
-            mChronometer.setVisibility(View.VISIBLE);
-        }
+        mChronometer.setVisibility(View.VISIBLE);
     }
 
     /**
@@ -180,7 +171,6 @@ public class AudioAttachmentView extends LinearLayout {
 
         mUseIncomingStyle = useIncomingStyle;
         mThemeColor = themeColor;
-        mPrepareOnPlayback = incoming && !MediaUtil.canAutoAccessIncomingMedia();
 
         if (!TextUtils.equals(currentUriString, newUriString)) {
             mDataSourceUri = dataSourceUri;
@@ -216,7 +206,7 @@ public class AudioAttachmentView extends LinearLayout {
     }
 
     /**
-     * Prepare the MediaPlayer, and if mPrepareOnPlayback, start playing the audio
+     * Prepare the MediaPlayer and start playing the audio
      */
     private void setupMediaPlayer() {
         Assert.notNull(mDataSourceUri);
@@ -332,7 +322,7 @@ public class AudioAttachmentView extends LinearLayout {
         updateVisualStyle();
         updateChronometerVisibility(false /* playing */);
 
-        if (mDataSourceUri != null && !mPrepareOnPlayback) {
+        if (mDataSourceUri != null) {
             // Prepare the media player, so we can read the duration of the audio.
             setupMediaPlayer();
         }
diff --git a/src/com/android/messaging/ui/LineWrapLayout.java b/src/com/android/messaging/ui/LineWrapLayout.java
index 5219811..032666a 100644
--- a/src/com/android/messaging/ui/LineWrapLayout.java
+++ b/src/com/android/messaging/ui/LineWrapLayout.java
@@ -22,9 +22,6 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 
-import com.android.messaging.util.OsUtil;
-import com.android.messaging.util.UiUtils;
-
 import java.util.ArrayList;
 
 /**
@@ -43,8 +40,8 @@ public class LineWrapLayout extends ViewGroup {
 
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
-        final int startPadding = UiUtils.getPaddingStart(this);
-        final int endPadding = UiUtils.getPaddingEnd(this);
+        final int startPadding = getPaddingStart();
+        final int endPadding = getPaddingEnd();
         final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
         final int widthSize = MeasureSpec.getSize(widthMeasureSpec) - startPadding - endPadding;
         final boolean isFixedSize = (widthMode == MeasureSpec.EXACTLY);
@@ -96,8 +93,8 @@ public class LineWrapLayout extends ViewGroup {
 
     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b) {
-        final int startPadding = UiUtils.getPaddingStart(this);
-        final int endPadding = UiUtils.getPaddingEnd(this);
+        final int startPadding = getPaddingStart();
+        final int endPadding = getPaddingEnd();
         int width = getWidth() - startPadding - endPadding;
         int y = getPaddingTop();
         int x = startPadding;
@@ -171,7 +168,7 @@ public class LineWrapLayout extends ViewGroup {
                 }
             }
 
-            if (OsUtil.isAtLeastJB_MR2() && getResources().getConfiguration()
+            if (getResources().getConfiguration()
                     .getLayoutDirection() == View.LAYOUT_DIRECTION_RTL) {
                 currChild.layout(width - startPositionX - childWidth, startPositionY,
                         width - startPositionX, startPositionY + childHeight);
@@ -214,19 +211,11 @@ public class LineWrapLayout extends ViewGroup {
         }
 
         public int getStartMargin() {
-            if (OsUtil.isAtLeastJB_MR2()) {
-                return getMarginStart();
-            } else {
-                return leftMargin;
-            }
+            return getMarginStart();
         }
 
         public int getEndMargin() {
-            if (OsUtil.isAtLeastJB_MR2()) {
-                return getMarginEnd();
-            } else {
-                return rightMargin;
-            }
+            return getMarginEnd();
         }
     }
 }
diff --git a/src/com/android/messaging/ui/SnackBarManager.java b/src/com/android/messaging/ui/SnackBarManager.java
index d5ca870..ceb7c5a 100644
--- a/src/com/android/messaging/ui/SnackBarManager.java
+++ b/src/com/android/messaging/ui/SnackBarManager.java
@@ -42,7 +42,6 @@ import com.android.messaging.ui.SnackBar.SnackBarListener;
 import com.android.messaging.util.AccessibilityUtil;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.TextUtil;
 import com.android.messaging.util.UiUtils;
 import com.google.common.base.Joiner;
@@ -354,22 +353,15 @@ public class SnackBarManager {
     private int getScreenBottomOffset(final SnackBar snackBar) {
         final WindowManager windowManager = getWindowManager(snackBar.getContext());
         final DisplayMetrics displayMetrics = new DisplayMetrics();
-        if (OsUtil.isAtLeastL()) {
-            windowManager.getDefaultDisplay().getRealMetrics(displayMetrics);
-        } else {
-            windowManager.getDefaultDisplay().getMetrics(displayMetrics);
-        }
+        windowManager.getDefaultDisplay().getRealMetrics(displayMetrics);
+
         final int screenHeight = displayMetrics.heightPixels;
 
-        if (OsUtil.isAtLeastL()) {
-            // In L, the navigation bar is included in the space for the popup window, so we have to
-            // offset by the size of the navigation bar
-            final Rect displayRect = new Rect();
-            snackBar.getParentView().getRootView().getWindowVisibleDisplayFrame(displayRect);
-            return screenHeight - displayRect.bottom;
-        }
-
-        return 0;
+        // In L, the navigation bar is included in the space for the popup window, so we have to
+        // offset by the size of the navigation bar
+        final Rect displayRect = new Rect();
+        snackBar.getParentView().getRootView().getWindowVisibleDisplayFrame(displayRect);
+        return screenHeight - displayRect.bottom;
     }
 
     private int getRelativeOffset(final SnackBar snackBar) {
diff --git a/src/com/android/messaging/ui/VideoThumbnailView.java b/src/com/android/messaging/ui/VideoThumbnailView.java
index 966336e..9336ddc 100644
--- a/src/com/android/messaging/ui/VideoThumbnailView.java
+++ b/src/com/android/messaging/ui/VideoThumbnailView.java
@@ -211,30 +211,19 @@ public class VideoThumbnailView extends FrameLayout {
         mVideoView.start();
     }
 
-    // TODO: The check could be added to MessagePartData itself so that all users of MessagePartData
-    // get the right behavior, instead of requiring all the users to do similar checks.
-    private static boolean shouldUseGenericVideoIcon(final boolean incomingMessage) {
-        return incomingMessage && !VideoThumbnailRequest.shouldShowIncomingVideoThumbnails();
-    }
-
     public void setSource(final MessagePartData part, final boolean incomingMessage) {
         if (part == null) {
             clearSource();
         } else {
             mVideoSource = part.getContentUri();
-            if (shouldUseGenericVideoIcon(incomingMessage)) {
-                mThumbnailImage.setImageResource(R.drawable.generic_video_icon);
-                mVideoWidth = ImageRequest.UNSPECIFIED_SIZE;
-                mVideoHeight = ImageRequest.UNSPECIFIED_SIZE;
-            } else {
-                mThumbnailImage.setImageResourceId(
-                        new MessagePartVideoThumbnailRequestDescriptor(part));
-                if (mVideoView != null) {
-                    mVideoView.setVideoURI(mVideoSource);
-                }
-                mVideoWidth = part.getWidth();
-                mVideoHeight = part.getHeight();
+
+            mThumbnailImage.setImageResourceId(
+                    new MessagePartVideoThumbnailRequestDescriptor(part));
+            if (mVideoView != null) {
+                mVideoView.setVideoURI(mVideoSource);
             }
+            mVideoWidth = part.getWidth();
+            mVideoHeight = part.getHeight();
         }
     }
 
@@ -243,16 +232,10 @@ public class VideoThumbnailView extends FrameLayout {
             clearSource();
         } else {
             mVideoSource = videoSource;
-            if (shouldUseGenericVideoIcon(incomingMessage)) {
-                mThumbnailImage.setImageResource(R.drawable.generic_video_icon);
-                mVideoWidth = ImageRequest.UNSPECIFIED_SIZE;
-                mVideoHeight = ImageRequest.UNSPECIFIED_SIZE;
-            } else {
-                mThumbnailImage.setImageResourceId(
-                        new MessagePartVideoThumbnailRequestDescriptor(videoSource));
-                if (mVideoView != null) {
-                    mVideoView.setVideoURI(videoSource);
-                }
+            mThumbnailImage.setImageResourceId(
+                    new MessagePartVideoThumbnailRequestDescriptor(videoSource));
+            if (mVideoView != null) {
+                mVideoView.setVideoURI(videoSource);
             }
         }
     }
diff --git a/src/com/android/messaging/ui/ViewPagerTabStrip.java b/src/com/android/messaging/ui/ViewPagerTabStrip.java
index e088296..c6ef539 100644
--- a/src/com/android/messaging/ui/ViewPagerTabStrip.java
+++ b/src/com/android/messaging/ui/ViewPagerTabStrip.java
@@ -25,7 +25,6 @@ import android.view.View;
 import android.widget.LinearLayout;
 
 import com.android.messaging.R;
-import com.android.messaging.util.OsUtil;
 
 public class ViewPagerTabStrip extends LinearLayout {
     private int mSelectedUnderlineThickness;
@@ -97,6 +96,6 @@ public class ViewPagerTabStrip extends LinearLayout {
     }
 
     private boolean isRtl() {
-        return OsUtil.isAtLeastJB_MR2() ? getLayoutDirection() == View.LAYOUT_DIRECTION_RTL : false;
+        return getLayoutDirection() == View.LAYOUT_DIRECTION_RTL;
     }
-}
\ No newline at end of file
+}
diff --git a/src/com/android/messaging/ui/ViewPagerTabs.java b/src/com/android/messaging/ui/ViewPagerTabs.java
index bb4aaaf..4af165a 100644
--- a/src/com/android/messaging/ui/ViewPagerTabs.java
+++ b/src/com/android/messaging/ui/ViewPagerTabs.java
@@ -35,7 +35,6 @@ import android.widget.Toast;
 
 import com.android.messaging.Factory;
 import com.android.messaging.R;
-import com.android.messaging.util.OsUtil;
 
 /**
  * Lightweight implementation of ViewPager tabs. This looks similar to traditional actionBar tabs,
@@ -130,14 +129,12 @@ public class ViewPagerTabs extends HorizontalScrollView implements ViewPager.OnP
         a.recycle();
 
         // enable shadow casting from view bounds
-        if (OsUtil.isAtLeastL()) {
-            setOutlineProvider(new ViewOutlineProvider() {
-                @Override
-                public void getOutline(View view, Outline outline) {
-                    outline.setRect(0, 0, view.getWidth(), view.getHeight());
-                }
-            });
-        }
+        setOutlineProvider(new ViewOutlineProvider() {
+            @Override
+            public void getOutline(View view, Outline outline) {
+                outline.setRect(0, 0, view.getWidth(), view.getHeight());
+            }
+        });
     }
 
     public void setViewPager(ViewPager viewPager) {
@@ -223,7 +220,7 @@ public class ViewPagerTabs extends HorizontalScrollView implements ViewPager.OnP
     }
 
     private int getRtlPosition(int position) {
-        if (OsUtil.isAtLeastJB_MR2() && Factory.get().getApplicationContext().getResources()
+        if (Factory.get().getApplicationContext().getResources()
                 .getConfiguration().getLayoutDirection() == View.LAYOUT_DIRECTION_RTL) {
             return mTabStrip.getChildCount() - 1 - position;
         }
diff --git a/src/com/android/messaging/ui/animation/RectEvaluatorCompat.java b/src/com/android/messaging/ui/animation/RectEvaluatorCompat.java
index e3c60fc..f8d6d1d 100644
--- a/src/com/android/messaging/ui/animation/RectEvaluatorCompat.java
+++ b/src/com/android/messaging/ui/animation/RectEvaluatorCompat.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,19 +20,12 @@ import android.animation.RectEvaluator;
 import android.animation.TypeEvaluator;
 import android.graphics.Rect;
 
-import com.android.messaging.util.OsUtil;
-
 /**
  * This evaluator can be used to perform type interpolation between <code>Rect</code> values.
- * It's backward compatible to Api Level 11.
  */
 public class RectEvaluatorCompat implements TypeEvaluator<Rect> {
     public static TypeEvaluator<Rect> create() {
-        if (OsUtil.isAtLeastJB_MR2()) {
-            return new RectEvaluator();
-        } else {
-            return new RectEvaluatorCompat();
-        }
+        return new RectEvaluator();
     }
 
     @Override
diff --git a/src/com/android/messaging/ui/animation/ViewGroupItemVerticalExplodeAnimation.java b/src/com/android/messaging/ui/animation/ViewGroupItemVerticalExplodeAnimation.java
index 7dc41fb..c757a83 100644
--- a/src/com/android/messaging/ui/animation/ViewGroupItemVerticalExplodeAnimation.java
+++ b/src/com/android/messaging/ui/animation/ViewGroupItemVerticalExplodeAnimation.java
@@ -15,7 +15,6 @@
  */
 package com.android.messaging.ui.animation;
 
-import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Context;
 import android.content.res.Resources;
@@ -34,7 +33,6 @@ import android.widget.FrameLayout;
 
 import com.android.messaging.R;
 import com.android.messaging.util.ImageUtils;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.UiUtils;
 
 /**
@@ -69,20 +67,15 @@ public class ViewGroupItemVerticalExplodeAnimation {
      */
     public static void startAnimationForView(final ViewGroup container, final View viewToAnimate,
             final View animationStagingView, final boolean snapshotView, final int duration) {
-        if (OsUtil.isAtLeastJB_MR2() && (viewToAnimate.getContext() instanceof Activity)) {
+        if ((viewToAnimate.getContext() instanceof Activity)) {
             new ViewExplodeAnimationJellyBeanMR2(viewToAnimate, container, snapshotView, duration)
                 .startAnimation();
-        } else {
-            // Pre JB_MR2, this animation can cause rendering failures which causes the framework
-            // to fall back to software rendering where camera preview isn't supported (b/18264647)
-            // just skip the animation to avoid this case.
         }
     }
 
     /**
      * Implementation class for API level >= 18.
      */
-    @TargetApi(18)
     private static class ViewExplodeAnimationJellyBeanMR2 {
         private final View mViewToAnimate;
         private final ViewGroup mContainer;
diff --git a/src/com/android/messaging/ui/appsettings/ApnSettingsActivity.java b/src/com/android/messaging/ui/appsettings/ApnSettingsActivity.java
index 13f775a..3ffa21c 100644
--- a/src/com/android/messaging/ui/appsettings/ApnSettingsActivity.java
+++ b/src/com/android/messaging/ui/appsettings/ApnSettingsActivity.java
@@ -49,7 +49,6 @@ import com.android.messaging.sms.ApnDatabase;
 import com.android.messaging.sms.BugleApnSettingsLoader;
 import com.android.messaging.ui.BugleActionBarActivity;
 import com.android.messaging.ui.UIIntents;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 public class ApnSettingsActivity extends BugleActionBarActivity {
@@ -150,13 +149,8 @@ public class ApnSettingsActivity extends BugleActionBarActivity {
             super.onCreate(icicle);
 
             mDatabase = ApnDatabase.getApnDatabase().getWritableDatabase();
-
-            if (OsUtil.isAtLeastL()) {
-                mUm = (UserManager) getActivity().getSystemService(Context.USER_SERVICE);
-                if (!mUm.hasUserRestriction(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS)) {
-                    setHasOptionsMenu(true);
-                }
-            } else {
+            mUm = (UserManager) getActivity().getSystemService(Context.USER_SERVICE);
+            if (!mUm.hasUserRestriction(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS)) {
                 setHasOptionsMenu(true);
             }
         }
@@ -172,8 +166,7 @@ public class ApnSettingsActivity extends BugleActionBarActivity {
                 lv.setEmptyView(empty);
             }
 
-            if (OsUtil.isAtLeastL() &&
-                    mUm.hasUserRestriction(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS)) {
+            if (mUm.hasUserRestriction(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS)) {
                 mUnavailable = true;
                 setPreferenceScreen(getPreferenceManager().createPreferenceScreen(getActivity()));
                 return;
diff --git a/src/com/android/messaging/ui/appsettings/ApplicationSettingsActivity.java b/src/com/android/messaging/ui/appsettings/ApplicationSettingsActivity.java
index 19979a9..2c617c1 100644
--- a/src/com/android/messaging/ui/appsettings/ApplicationSettingsActivity.java
+++ b/src/com/android/messaging/ui/appsettings/ApplicationSettingsActivity.java
@@ -36,7 +36,6 @@ import com.android.messaging.ui.LicenseActivity;
 import com.android.messaging.ui.UIIntents;
 import com.android.messaging.util.BuglePrefs;
 import com.android.messaging.util.DebugUtils;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 public class ApplicationSettingsActivity extends BugleActionBarActivity {
@@ -151,35 +150,14 @@ public class ApplicationSettingsActivity extends BugleActionBarActivity {
         }
 
         private void updateSmsEnabledPreferences() {
-            if (!OsUtil.isAtLeastKLP()) {
+            final String defaultSmsAppLabel = getString(R.string.default_sms_app,
+                    PhoneUtils.getDefault().getDefaultSmsAppLabel());
+            if (PhoneUtils.getDefault().isDefaultSmsApp()) {
                 getPreferenceScreen().removePreference(mSmsDisabledPreference);
-                getPreferenceScreen().removePreference(mSmsEnabledPreference);
+                mSmsEnabledPreference.setSummary(defaultSmsAppLabel);
             } else {
-                final String defaultSmsAppLabel = getString(R.string.default_sms_app,
-                        PhoneUtils.getDefault().getDefaultSmsAppLabel());
-                boolean isSmsEnabledBeforeState;
-                boolean isSmsEnabledCurrentState;
-                if (PhoneUtils.getDefault().isDefaultSmsApp()) {
-                    if (getPreferenceScreen().findPreference(mSmsEnabledPrefKey) == null) {
-                        getPreferenceScreen().addPreference(mSmsEnabledPreference);
-                        isSmsEnabledBeforeState = false;
-                    } else {
-                        isSmsEnabledBeforeState = true;
-                    }
-                    isSmsEnabledCurrentState = true;
-                    getPreferenceScreen().removePreference(mSmsDisabledPreference);
-                    mSmsEnabledPreference.setSummary(defaultSmsAppLabel);
-                } else {
-                    if (getPreferenceScreen().findPreference(mSmsDisabledPrefKey) == null) {
-                        getPreferenceScreen().addPreference(mSmsDisabledPreference);
-                        isSmsEnabledBeforeState = true;
-                    } else {
-                        isSmsEnabledBeforeState = false;
-                    }
-                    isSmsEnabledCurrentState = false;
-                    getPreferenceScreen().removePreference(mSmsEnabledPreference);
-                    mSmsDisabledPreference.setSummary(defaultSmsAppLabel);
-                }
+                getPreferenceScreen().removePreference(mSmsEnabledPreference);
+                mSmsDisabledPreference.setSummary(defaultSmsAppLabel);
             }
             mIsSmsPreferenceClicked = false;
         }
diff --git a/src/com/android/messaging/ui/contact/ContactPickerFragment.java b/src/com/android/messaging/ui/contact/ContactPickerFragment.java
index e201074..1edf50b 100644
--- a/src/com/android/messaging/ui/contact/ContactPickerFragment.java
+++ b/src/com/android/messaging/ui/contact/ContactPickerFragment.java
@@ -60,7 +60,6 @@ import com.android.messaging.util.Assert.RunsOnMainThread;
 import com.android.messaging.util.ContactUtil;
 import com.android.messaging.util.ImeUtil;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.UiUtils;
 import com.google.common.annotations.VisibleForTesting;
@@ -503,10 +502,6 @@ public class ContactPickerFragment extends Fragment implements ContactPickerData
      * @param show whether the contact lists are to be shown or hidden.
      */
     private void startExplodeTransitionForContactLists(final boolean show) {
-        if (!OsUtil.isAtLeastL()) {
-            // Explode animation is not supported pre-L.
-            return;
-        }
         final Explode transition = new Explode();
         final Rect epicenter = mPendingExplodeView == null ? null :
             UiUtils.getMeasuredBoundsOnScreen(mPendingExplodeView);
@@ -533,10 +528,6 @@ public class ContactPickerFragment extends Fragment implements ContactPickerData
      * the transition manager for pending explode transition.
      */
     private void toggleContactListItemsVisibilityForPendingTransition(final boolean show) {
-        if (!OsUtil.isAtLeastL()) {
-            // Explode animation is not supported pre-L.
-            return;
-        }
         mAllContactsListViewHolder.toggleVisibilityForPendingTransition(show, mPendingExplodeView);
         mFrequentContactsListViewHolder.toggleVisibilityForPendingTransition(show,
                 mPendingExplodeView);
diff --git a/src/com/android/messaging/ui/contact/ContactRecipientAdapter.java b/src/com/android/messaging/ui/contact/ContactRecipientAdapter.java
index e330447..6cd3b7f 100644
--- a/src/com/android/messaging/ui/contact/ContactRecipientAdapter.java
+++ b/src/com/android/messaging/ui/contact/ContactRecipientAdapter.java
@@ -39,7 +39,6 @@ import com.android.messaging.util.BugleGservices;
 import com.android.messaging.util.BugleGservicesKeys;
 import com.android.messaging.util.ContactRecipientEntryUtils;
 import com.android.messaging.util.ContactUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.text.Collator;
@@ -129,30 +128,26 @@ public final class ContactRecipientAdapter extends BaseRecipientAdapter {
                         new Cursor[]{personalFilterEmailsCursor, personalFilterPhonesCursor});
                 final CursorResult cursorResult =
                         new CursorResult(personalCursor, false /* sorted */);
-                if (OsUtil.isAtLeastN()) {
-                    // Including enterprise result starting from N.
-                    final Cursor enterpriseFilterPhonesCursor = ContactUtil.filterPhonesEnterprise(
-                            getContext(), searchText).performSynchronousQuery();
-                    final Cursor enterpriseFilterEmailsCursor = ContactUtil.filterEmailsEnterprise(
-                            getContext(), searchText).performSynchronousQuery();
-                    final Cursor enterpriseCursor = new MergeCursor(
-                            new Cursor[]{enterpriseFilterEmailsCursor,
-                                    enterpriseFilterPhonesCursor});
-                    cursorResult.enterpriseCursor = enterpriseCursor;
-                }
+                // Including enterprise result starting from N.
+                final Cursor enterpriseFilterPhonesCursor = ContactUtil.filterPhonesEnterprise(
+                        getContext(), searchText).performSynchronousQuery();
+                final Cursor enterpriseFilterEmailsCursor = ContactUtil.filterEmailsEnterprise(
+                        getContext(), searchText).performSynchronousQuery();
+                final Cursor enterpriseCursor = new MergeCursor(
+                        new Cursor[]{enterpriseFilterEmailsCursor,
+                                enterpriseFilterPhonesCursor});
+                cursorResult.enterpriseCursor = enterpriseCursor;
                 return cursorResult;
             } else {
                 final Cursor personalFilterDestinationCursor = ContactUtil
                         .filterDestination(getContext(), searchText).performSynchronousQuery();
                 final CursorResult cursorResult = new CursorResult(personalFilterDestinationCursor,
                         true);
-                if (OsUtil.isAtLeastN()) {
-                    // Including enterprise result starting from N.
-                    final Cursor enterpriseFilterDestinationCursor = ContactUtil
-                            .filterDestinationEnterprise(getContext(), searchText)
-                            .performSynchronousQuery();
-                    cursorResult.enterpriseCursor = enterpriseFilterDestinationCursor;
-                }
+                // Including enterprise result starting from N.
+                final Cursor enterpriseFilterDestinationCursor = ContactUtil
+                        .filterDestinationEnterprise(getContext(), searchText)
+                        .performSynchronousQuery();
+                cursorResult.enterpriseCursor = enterpriseFilterDestinationCursor;
                 return cursorResult;
             }
         }
diff --git a/src/com/android/messaging/ui/conversation/ComposeMessageView.java b/src/com/android/messaging/ui/conversation/ComposeMessageView.java
index a8c1e4f..a7dba83 100644
--- a/src/com/android/messaging/ui/conversation/ComposeMessageView.java
+++ b/src/com/android/messaging/ui/conversation/ComposeMessageView.java
@@ -67,7 +67,6 @@ import com.android.messaging.util.BuglePrefs;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
 import com.android.messaging.util.MediaUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.SafeAsyncTask;
 import com.android.messaging.util.UiUtils;
@@ -867,18 +866,16 @@ public class ComposeMessageView extends LinearLayout
 
     // Set accessibility traversal order of the components in the send widget.
     private void setSendWidgetAccessibilityTraversalOrder(final int mode) {
-        if (OsUtil.isAtLeastL_MR1()) {
-            mAttachMediaButton.setAccessibilityTraversalBefore(R.id.compose_message_text);
-            switch (mode) {
-                case SEND_WIDGET_MODE_SIM_SELECTOR:
-                    mComposeEditText.setAccessibilityTraversalBefore(R.id.self_send_icon);
-                    break;
-                case SEND_WIDGET_MODE_SEND_BUTTON:
-                    mComposeEditText.setAccessibilityTraversalBefore(R.id.send_message_button);
-                    break;
-                default:
-                    break;
-            }
+        mAttachMediaButton.setAccessibilityTraversalBefore(R.id.compose_message_text);
+        switch (mode) {
+            case SEND_WIDGET_MODE_SIM_SELECTOR:
+                mComposeEditText.setAccessibilityTraversalBefore(R.id.self_send_icon);
+                break;
+            case SEND_WIDGET_MODE_SEND_BUTTON:
+                mComposeEditText.setAccessibilityTraversalBefore(R.id.send_message_button);
+                break;
+            default:
+                break;
         }
     }
 
@@ -979,8 +976,7 @@ public class ComposeMessageView extends LinearLayout
     }
 
     public static boolean shouldShowSimSelector(final ConversationData convData) {
-        return OsUtil.isAtLeastL_MR1() &&
-                convData.getSelfParticipantsCountExcludingDefault(true /* activeOnly */) > 1;
+        return convData.getSelfParticipantsCountExcludingDefault(true /* activeOnly */) > 1;
     }
 
     public void sendMessageIgnoreMessageSizeLimit() {
diff --git a/src/com/android/messaging/ui/conversation/ConversationActivity.java b/src/com/android/messaging/ui/conversation/ConversationActivity.java
index d8d3157..c9769ac 100644
--- a/src/com/android/messaging/ui/conversation/ConversationActivity.java
+++ b/src/com/android/messaging/ui/conversation/ConversationActivity.java
@@ -39,7 +39,6 @@ import com.android.messaging.ui.conversationlist.ConversationListActivity;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.UiUtils;
 
 public class ConversationActivity extends BugleActionBarActivity
@@ -348,11 +347,7 @@ public class ConversationActivity extends BugleActionBarActivity
     public void onFinishCurrentConversation() {
         // Simply finish the current activity. The current design is to leave any empty
         // conversations as is.
-        if (OsUtil.isAtLeastL()) {
-            finishAfterTransition();
-        } else {
-            finish();
-        }
+        finishAfterTransition();
     }
 
     @Override
diff --git a/src/com/android/messaging/ui/conversation/ConversationFastScroller.java b/src/com/android/messaging/ui/conversation/ConversationFastScroller.java
index f17f11e..9184d71 100644
--- a/src/com/android/messaging/ui/conversation/ConversationFastScroller.java
+++ b/src/com/android/messaging/ui/conversation/ConversationFastScroller.java
@@ -41,7 +41,6 @@ import com.android.messaging.R;
 import com.android.messaging.datamodel.data.ConversationMessageData;
 import com.android.messaging.ui.ConversationDrawables;
 import com.android.messaging.util.Dates;
-import com.android.messaging.util.OsUtil;
 
 /**
  * Adds a "fast-scroll" bar to the conversation RecyclerView that shows the current position within
@@ -63,10 +62,7 @@ public class ConversationFastScroller extends RecyclerView.OnScrollListener impl
      *         (the feature requires Jellybean MR2 or newer)
      */
     public static ConversationFastScroller addTo(RecyclerView rv, int position) {
-        if (OsUtil.isAtLeastJB_MR2()) {
-            return new ConversationFastScroller(rv, position);
-        }
-        return null;
+        return new ConversationFastScroller(rv, position);
     }
 
     public static final int POSITION_RIGHT_SIDE = 0;
@@ -164,20 +160,12 @@ public class ConversationFastScroller extends RecyclerView.OnScrollListener impl
     public void refreshConversationThemeColor() {
         mPreviewTextView.setBackground(
                 ConversationDrawables.get().getFastScrollPreviewDrawable(mPosRight));
-        if (OsUtil.isAtLeastL()) {
-            final StateListDrawable drawable = new StateListDrawable();
-            drawable.addState(new int[]{ android.R.attr.state_pressed },
-                    ConversationDrawables.get().getFastScrollThumbDrawable(true /* pressed */));
-            drawable.addState(StateSet.WILD_CARD,
-                    ConversationDrawables.get().getFastScrollThumbDrawable(false /* pressed */));
-            mThumbImageView.setImageDrawable(drawable);
-        } else {
-            // Android pre-L doesn't seem to handle a StateListDrawable containing a tinted
-            // drawable (it's rendered in the filter base color, which is red), so fall back to
-            // just the regular (non-pressed) drawable.
-            mThumbImageView.setImageDrawable(
-                    ConversationDrawables.get().getFastScrollThumbDrawable(false /* pressed */));
-        }
+        final StateListDrawable drawable = new StateListDrawable();
+        drawable.addState(new int[]{ android.R.attr.state_pressed },
+                ConversationDrawables.get().getFastScrollThumbDrawable(true /* pressed */));
+        drawable.addState(StateSet.WILD_CARD,
+                ConversationDrawables.get().getFastScrollThumbDrawable(false /* pressed */));
+        mThumbImageView.setImageDrawable(drawable);
     }
 
     @Override
diff --git a/src/com/android/messaging/ui/conversation/ConversationFragment.java b/src/com/android/messaging/ui/conversation/ConversationFragment.java
index 181e878..171c83d 100644
--- a/src/com/android/messaging/ui/conversation/ConversationFragment.java
+++ b/src/com/android/messaging/ui/conversation/ConversationFragment.java
@@ -1012,7 +1012,7 @@ public class ConversationFragment extends Fragment implements ConversationDataLi
     }
 
     private FragmentManager getFragmentManagerToUse() {
-        return OsUtil.isAtLeastJB_MR1() ? getChildFragmentManager() : getFragmentManager();
+        return getChildFragmentManager();
     }
 
     public MediaPicker getMediaPicker() {
@@ -1158,21 +1158,7 @@ public class ConversationFragment extends Fragment implements ConversationDataLi
                         }
                     })
                     .setNegativeButton(android.R.string.cancel, null);
-            if (OsUtil.isAtLeastJB_MR1()) {
-                builder.setOnDismissListener(new OnDismissListener() {
-                    @Override
-                    public void onDismiss(final DialogInterface dialog) {
-                        mHost.dismissActionMode();
-                    }
-                });
-            } else {
-                builder.setOnCancelListener(new OnCancelListener() {
-                    @Override
-                    public void onCancel(final DialogInterface dialog) {
-                        mHost.dismissActionMode();
-                    }
-                });
-            }
+            builder.setOnDismissListener(dialog -> mHost.dismissActionMode());
             builder.create().show();
         } else {
             warnOfMissingActionConditions(false /*sending*/,
diff --git a/src/com/android/messaging/ui/conversation/ConversationSimSelector.java b/src/com/android/messaging/ui/conversation/ConversationSimSelector.java
index 94c7e76..6d8f28f 100644
--- a/src/com/android/messaging/ui/conversation/ConversationSimSelector.java
+++ b/src/com/android/messaging/ui/conversation/ConversationSimSelector.java
@@ -26,7 +26,6 @@ import com.android.messaging.datamodel.data.SubscriptionListData.SubscriptionLis
 import com.android.messaging.ui.conversation.SimSelectorView.SimSelectorViewListener;
 import com.android.messaging.util.AccessibilityUtil;
 import com.android.messaging.util.Assert;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.ThreadUtil;
 
 /**
@@ -47,7 +46,6 @@ abstract class ConversationSimSelector extends ConversationInput {
         mSimSelectorView.bind(subscriptionListData);
         mDataReady = subscriptionListData != null && subscriptionListData.hasData();
         if (mPendingShow != null && mDataReady) {
-            Assert.isTrue(OsUtil.isAtLeastL_MR1());
             final boolean show = mPendingShow.first;
             final boolean animate = mPendingShow.second;
             ThreadUtil.getMainThreadHandler().post(new Runnable() {
@@ -88,10 +86,6 @@ abstract class ConversationSimSelector extends ConversationInput {
     }
 
     private boolean showHide(final boolean show, final boolean animate) {
-        if (!OsUtil.isAtLeastL_MR1()) {
-            return false;
-        }
-
         if (mDataReady) {
             mSimSelectorView.showOrHide(show, animate);
             return mSimSelectorView.isOpen() == show;
diff --git a/src/com/android/messaging/ui/conversation/MessageDetailsDialog.java b/src/com/android/messaging/ui/conversation/MessageDetailsDialog.java
index 89b9148..30bb628 100644
--- a/src/com/android/messaging/ui/conversation/MessageDetailsDialog.java
+++ b/src/com/android/messaging/ui/conversation/MessageDetailsDialog.java
@@ -37,7 +37,6 @@ import com.android.messaging.util.Assert;
 import com.android.messaging.util.Assert.DoesNotRunOnMainThread;
 import com.android.messaging.util.Dates;
 import com.android.messaging.util.DebugUtils;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.SafeAsyncTask;
 
@@ -356,9 +355,7 @@ public class MessageDetailsDialog {
 
     private static void appendSimInfo(final Resources res,
             final ParticipantData self, final StringBuilder outString) {
-        if (!OsUtil.isAtLeastL_MR1()
-                || self == null
-                || PhoneUtils.getDefault().getActiveSubscriptionCount() < 2) {
+        if (self == null || PhoneUtils.getDefault().getActiveSubscriptionCount() < 2) {
             return;
         }
         // The appended SIM info would look like:
diff --git a/src/com/android/messaging/ui/conversation/SimIconView.java b/src/com/android/messaging/ui/conversation/SimIconView.java
index 91aac96..0cf9bd4 100644
--- a/src/com/android/messaging/ui/conversation/SimIconView.java
+++ b/src/com/android/messaging/ui/conversation/SimIconView.java
@@ -26,7 +26,6 @@ import android.view.ViewOutlineProvider;
 import com.android.messaging.ui.ContactIconView;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.AvatarUriUtil;
-import com.android.messaging.util.OsUtil;
 
 /**
  * Shows SIM avatar icon in the SIM switcher / Self-send button.
@@ -34,14 +33,12 @@ import com.android.messaging.util.OsUtil;
 public class SimIconView extends ContactIconView {
     public SimIconView(Context context, AttributeSet attrs) {
         super(context, attrs);
-        if (OsUtil.isAtLeastL()) {
-            setOutlineProvider(new ViewOutlineProvider() {
-                @Override
-                public void getOutline(View v, Outline outline) {
-                    outline.setOval(0, 0, v.getWidth(), v.getHeight());
-                }
-            });
-        }
+        setOutlineProvider(new ViewOutlineProvider() {
+            @Override
+            public void getOutline(View v, Outline outline) {
+                outline.setOval(0, 0, v.getWidth(), v.getHeight());
+            }
+        });
     }
 
     @Override
diff --git a/src/com/android/messaging/ui/conversationlist/ConversationListItemView.java b/src/com/android/messaging/ui/conversationlist/ConversationListItemView.java
index 9331d10..3e95299 100644
--- a/src/com/android/messaging/ui/conversationlist/ConversationListItemView.java
+++ b/src/com/android/messaging/ui/conversationlist/ConversationListItemView.java
@@ -53,7 +53,6 @@ import com.android.messaging.ui.SnackBarInteraction;
 import com.android.messaging.util.Assert;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.ImageUtils;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 import com.android.messaging.util.Typefaces;
 import com.android.messaging.util.UiUtils;
@@ -168,9 +167,7 @@ public class ConversationListItemView extends FrameLayout implements OnClickList
         mListItemReadTypeface = Typefaces.getRobotoNormal();
         mListItemUnreadTypeface = Typefaces.getRobotoBold();
 
-        if (OsUtil.isAtLeastL()) {
-            setTransitionGroup(true);
-        }
+        setTransitionGroup(true);
     }
 
     @Override
diff --git a/src/com/android/messaging/ui/debug/DebugMmsConfigFragment.java b/src/com/android/messaging/ui/debug/DebugMmsConfigFragment.java
index f7da331..a129fa8 100644
--- a/src/com/android/messaging/ui/debug/DebugMmsConfigFragment.java
+++ b/src/com/android/messaging/ui/debug/DebugMmsConfigFragment.java
@@ -31,10 +31,8 @@ import android.widget.Spinner;
 import android.widget.TextView;
 
 import com.android.messaging.R;
-import com.android.messaging.datamodel.data.ParticipantData;
 import com.android.messaging.sms.MmsConfig;
 import com.android.messaging.ui.debug.DebugMmsConfigItemView.MmsConfigItemListener;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 import java.util.ArrayList;
@@ -79,11 +77,8 @@ public class DebugMmsConfigFragment extends Fragment {
     }
 
     public static Integer[] getActiveSubIds() {
-        if (!OsUtil.isAtLeastL_MR1()) {
-            return new Integer[] { ParticipantData.DEFAULT_SELF_SUB_ID };
-        }
         final List<SubscriptionInfo> subRecords =
-                PhoneUtils.getDefault().toLMr1().getActiveSubscriptionInfoList();
+                PhoneUtils.getDefault().getActiveSubscriptionInfoList();
         if (subRecords == null) {
             return new Integer[0];
         }
diff --git a/src/com/android/messaging/ui/mediapicker/MediaChooser.java b/src/com/android/messaging/ui/mediapicker/MediaChooser.java
index 0549e5b..e36240c 100644
--- a/src/com/android/messaging/ui/mediapicker/MediaChooser.java
+++ b/src/com/android/messaging/ui/mediapicker/MediaChooser.java
@@ -34,7 +34,6 @@ import com.android.messaging.datamodel.data.MediaPickerData;
 import com.android.messaging.datamodel.data.DraftMessageData.DraftMessageSubscriptionDataProvider;
 import com.android.messaging.ui.BasePagerViewHolder;
 import com.android.messaging.util.Assert;
-import com.android.messaging.util.OsUtil;
 
 abstract class MediaChooser extends BasePagerViewHolder
         implements DraftMessageSubscriptionDataProvider {
@@ -107,8 +106,7 @@ abstract class MediaChooser extends BasePagerViewHolder
     }
 
     protected FragmentManager getFragmentManager() {
-        return OsUtil.isAtLeastJB_MR1() ? mMediaPicker.getChildFragmentManager() :
-                mMediaPicker.getFragmentManager();
+        return mMediaPicker.getChildFragmentManager();
     }
     protected LayoutInflater getLayoutInflater() {
         return LayoutInflater.from(getContext());
diff --git a/src/com/android/messaging/ui/mediapicker/MediaPickerPanel.java b/src/com/android/messaging/ui/mediapicker/MediaPickerPanel.java
index 56b0a03..de2be00 100644
--- a/src/com/android/messaging/ui/mediapicker/MediaPickerPanel.java
+++ b/src/com/android/messaging/ui/mediapicker/MediaPickerPanel.java
@@ -31,7 +31,6 @@ import android.widget.LinearLayout;
 import com.android.messaging.R;
 import com.android.messaging.ui.PagingAwareViewPager;
 import com.android.messaging.util.Assert;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.UiUtils;
 
 /**
@@ -202,7 +201,7 @@ public class MediaPickerPanel extends ViewGroup {
     private int getDesiredHeight() {
         if (mFullScreen) {
             int fullHeight = getContext().getResources().getDisplayMetrics().heightPixels;
-            if (OsUtil.isAtLeastKLP() && isAttachedToWindow()) {
+            if (isAttachedToWindow()) {
                 // When we're attached to the window, we can get an accurate height, not necessary
                 // on older API level devices because they don't include the action bar height
                 View composeContainer =
diff --git a/src/com/android/messaging/util/AccessibilityUtil.java b/src/com/android/messaging/util/AccessibilityUtil.java
index 788f482..711344f 100644
--- a/src/com/android/messaging/util/AccessibilityUtil.java
+++ b/src/com/android/messaging/util/AccessibilityUtil.java
@@ -73,8 +73,7 @@ public class AccessibilityUtil {
         }
 
         // Jelly Bean added support for speaking text verbatim
-        final int eventType = OsUtil.isAtLeastJB() ? AccessibilityEvent.TYPE_ANNOUNCEMENT
-                : AccessibilityEvent.TYPE_VIEW_FOCUSED;
+        final int eventType = AccessibilityEvent.TYPE_ANNOUNCEMENT;
 
         // Construct an accessibility event with the minimum recommended
         // attributes. An event without a class name or package may be dropped.
@@ -101,11 +100,7 @@ public class AccessibilityUtil {
      * @return boolean Boolean indicating whether the currently locale is RTL.
      */
     public static boolean isLayoutRtl(final View view) {
-        if (OsUtil.isAtLeastJB_MR1()) {
-            return View.LAYOUT_DIRECTION_RTL == view.getLayoutDirection();
-        } else {
-            return false;
-        }
+        return View.LAYOUT_DIRECTION_RTL == view.getLayoutDirection();
     }
 
     public static String getVocalizedPhoneNumber(final Resources res, final String phoneNumber) {
diff --git a/src/com/android/messaging/util/BugleActivityUtil.java b/src/com/android/messaging/util/BugleActivityUtil.java
index 7f722fd..d83e895 100644
--- a/src/com/android/messaging/util/BugleActivityUtil.java
+++ b/src/com/android/messaging/util/BugleActivityUtil.java
@@ -62,10 +62,6 @@ public class BugleActivityUtil {
      * @return true if the user has SMS permissions, otherwise false.
      */
     private static boolean checkHasSmsPermissionsForUser(Context context, Activity activity) {
-        if (!OsUtil.isAtLeastL()) {
-            // UserManager.DISALLOW_SMS added in L. No multiuser phones before this
-            return true;
-        }
         UserManager userManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
         if (userManager.hasUserRestriction(UserManager.DISALLOW_SMS)) {
             new AlertDialog.Builder(activity)
diff --git a/src/com/android/messaging/util/ConnectivityUtil.java b/src/com/android/messaging/util/ConnectivityUtil.java
index a7467e4..68e5b46 100644
--- a/src/com/android/messaging/util/ConnectivityUtil.java
+++ b/src/com/android/messaging/util/ConnectivityUtil.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,13 +26,6 @@ import com.android.messaging.datamodel.data.ParticipantData;
 
 /**
  * ConnectivityUtil listens to the network service state changes.
- *
- * On N and beyond, This class instance can be created via ConnectivityUtil(context, subId), use
- * ConnectivityUtil(context) for others.
- *
- * Note that TelephonyManager has createForSubscriptionId() for a specific subId from N but listen()
- * does not use the subId on the manager, and uses the default subId on PhoneStateListener. From O,
- * the manager uses its' own subId in listen().
  */
 public class ConnectivityUtil {
     // Assume not connected until informed differently
@@ -45,12 +39,7 @@ public class ConnectivityUtil {
         public void onPhoneStateChanged(int serviceState);
     }
 
-    public ConnectivityUtil(final Context context) {
-        mTelephonyManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
-    }
-
     public ConnectivityUtil(final Context context, final int subId) {
-        Assert.isTrue(OsUtil.isAtLeastN());
         mTelephonyManager =
                 ((TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE))
                         .createForSubscriptionId(subId);
diff --git a/src/com/android/messaging/util/ContactUtil.java b/src/com/android/messaging/util/ContactUtil.java
index 94af3ba..855f26c 100644
--- a/src/com/android/messaging/util/ContactUtil.java
+++ b/src/com/android/messaging/util/ContactUtil.java
@@ -519,27 +519,21 @@ public class ContactUtil {
      * Returns if a given contact id belongs to managed profile.
      */
     public static boolean isEnterpriseContactId(final long contactId) {
-        return OsUtil.isAtLeastL() && ContactsContract.Contacts.isEnterpriseContactId(contactId);
+        return ContactsContract.Contacts.isEnterpriseContactId(contactId);
     }
 
     /**
      * Returns Email lookup uri that will query both primary and corp profile
      */
     private static Uri getEmailContentLookupUri() {
-        if (OsUtil.isAtLeastM()) {
-            return Email.ENTERPRISE_CONTENT_LOOKUP_URI;
-        }
-        return Email.CONTENT_LOOKUP_URI;
+        return Email.ENTERPRISE_CONTENT_LOOKUP_URI;
     }
 
     /**
      * Returns PhoneLookup URI.
      */
     public static Uri getPhoneLookupUri() {
-        if (OsUtil.isAtLeastM()) {
-            return PhoneLookup.ENTERPRISE_CONTENT_FILTER_URI;
-        }
-        return PhoneLookup.CONTENT_FILTER_URI;
+        return PhoneLookup.ENTERPRISE_CONTENT_FILTER_URI;
     }
 
     public static boolean hasReadContactsPermission() {
diff --git a/src/com/android/messaging/util/DebugUtils.java b/src/com/android/messaging/util/DebugUtils.java
index 6e33f48..cab156c 100644
--- a/src/com/android/messaging/util/DebugUtils.java
+++ b/src/com/android/messaging/util/DebugUtils.java
@@ -302,10 +302,7 @@ public class DebugUtils {
                     final int length = dis.readInt();
                     final byte[] pdu = new byte[length];
                     dis.read(pdu, 0, length);
-                    messagesTemp[i] =
-                            OsUtil.isAtLeastM()
-                                    ? SmsMessage.createFromPdu(pdu, format)
-                                    : SmsMessage.createFromPdu(pdu);
+                    messagesTemp[i] = SmsMessage.createFromPdu(pdu, format);
                 }
                 messages = messagesTemp;
             } catch (final FileNotFoundException e) {
diff --git a/src/com/android/messaging/util/ImageUtils.java b/src/com/android/messaging/util/ImageUtils.java
index e541d69..71da978 100644
--- a/src/com/android/messaging/util/ImageUtils.java
+++ b/src/com/android/messaging/util/ImageUtils.java
@@ -174,11 +174,7 @@ public class ImageUtils {
      */
     @SuppressWarnings("deprecation")
     public static void setBackgroundDrawableOnView(final View view, final Drawable drawable) {
-        if (OsUtil.isAtLeastJB()) {
-            view.setBackground(drawable);
-        } else {
-            view.setBackgroundDrawable(drawable);
-        }
+        view.setBackground(drawable);
     }
 
     /**
diff --git a/src/com/android/messaging/util/MediaUtil.java b/src/com/android/messaging/util/MediaUtil.java
index c23ded3..f25354c 100644
--- a/src/com/android/messaging/util/MediaUtil.java
+++ b/src/com/android/messaging/util/MediaUtil.java
@@ -33,8 +33,4 @@ public abstract class MediaUtil {
      */
     public abstract void playSound(final Context context, final int resId,
             final OnCompletionListener completionListener);
-
-    public static boolean canAutoAccessIncomingMedia() {
-        return OsUtil.isAtLeastM();
-    }
 }
diff --git a/src/com/android/messaging/util/NotificationsUtil.java b/src/com/android/messaging/util/NotificationsUtil.java
index 591f15a..ef0451a 100644
--- a/src/com/android/messaging/util/NotificationsUtil.java
+++ b/src/com/android/messaging/util/NotificationsUtil.java
@@ -20,7 +20,6 @@ import android.app.NotificationChannel;
 import android.app.NotificationChannelGroup;
 import android.app.NotificationManager;
 import android.content.Context;
-import android.os.Build;
 
 public final class NotificationsUtil {
     public static final String DEFAULT_CHANNEL_ID = "messaging_channel";
@@ -37,10 +36,6 @@ public final class NotificationsUtil {
 
     public static void createNotificationChannel(Context context, String id,
             String title, int priority, String groupId) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-            return;
-        }
-
         NotificationManager manager = context.getSystemService(NotificationManager.class);
         NotificationChannel existing = manager.getNotificationChannel(id);
         if (existing != null) {
@@ -56,20 +51,12 @@ public final class NotificationsUtil {
     }
 
     public static void deleteNotificationChannel(Context context, String id) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-            return;
-        }
-
         NotificationManager manager = context.getSystemService(NotificationManager.class);
         manager.deleteNotificationChannel(id);
     }
 
     public static void createNotificationChannelGroup(Context context, String id,
             int titleResId) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-            return;
-        }
-
         NotificationManager manager = context.getSystemService(NotificationManager.class);
         NotificationChannelGroup existing = manager.getNotificationChannelGroup(id);
         if (existing != null) {
@@ -82,19 +69,11 @@ public final class NotificationsUtil {
     }
 
     public static NotificationChannel getNotificationChannel(Context context, String id) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-            return null;
-        }
-
         NotificationManager manager = context.getSystemService(NotificationManager.class);
         return manager.getNotificationChannel(id);
     }
 
     public static NotificationChannelGroup getNotificationChannelGroup(Context context, String id) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-            return null;
-        }
-
         NotificationManager manager = context.getSystemService(NotificationManager.class);
         return manager.getNotificationChannelGroup(id);
     }
diff --git a/src/com/android/messaging/util/OsUtil.java b/src/com/android/messaging/util/OsUtil.java
index 1d9742a..c84fa0c 100644
--- a/src/com/android/messaging/util/OsUtil.java
+++ b/src/com/android/messaging/util/OsUtil.java
@@ -19,10 +19,8 @@ package com.android.messaging.util;
 import android.Manifest;
 import android.content.Context;
 import android.content.pm.PackageManager;
-import android.os.Build;
 import android.os.UserHandle;
 import android.os.UserManager;
-import androidx.core.os.BuildCompat;
 
 import com.android.messaging.Factory;
 
@@ -34,124 +32,20 @@ import java.util.Set;
  * Android OS version utilities
  */
 public class OsUtil {
-    private static boolean sIsAtLeastICS_MR1;
-    private static boolean sIsAtLeastJB;
-    private static boolean sIsAtLeastJB_MR1;
-    private static boolean sIsAtLeastJB_MR2;
-    private static boolean sIsAtLeastKLP;
-    private static boolean sIsAtLeastL;
-    private static boolean sIsAtLeastL_MR1;
-    private static boolean sIsAtLeastM;
-    private static boolean sIsAtLeastN;
 
     private static Boolean sIsSecondaryUser = null;
 
-    static {
-        final int v = getApiVersion();
-        sIsAtLeastICS_MR1 = v >= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1;
-        sIsAtLeastJB = v >= android.os.Build.VERSION_CODES.JELLY_BEAN;
-        sIsAtLeastJB_MR1 = v >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR1;
-        sIsAtLeastJB_MR2 = v >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR2;
-        sIsAtLeastKLP = v >= android.os.Build.VERSION_CODES.KITKAT;
-        sIsAtLeastL = v >= android.os.Build.VERSION_CODES.LOLLIPOP;
-        sIsAtLeastL_MR1 = v >= android.os.Build.VERSION_CODES.LOLLIPOP_MR1;
-        sIsAtLeastM = v >= android.os.Build.VERSION_CODES.M;
-        sIsAtLeastN = BuildCompat.isAtLeastN();
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least Ice Cream Sandwich
-     *  MR1 (API level 15).
-     */
-    public static boolean isAtLeastICS_MR1() {
-        return sIsAtLeastICS_MR1;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least Jelly Bean
-     *  (API level 16).
-     */
-    public static boolean isAtLeastJB() {
-        return sIsAtLeastJB;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least Jelly Bean MR1
-     *  (API level 17).
-     */
-    public static boolean isAtLeastJB_MR1() {
-        return sIsAtLeastJB_MR1;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least Jelly Bean MR2
-     *  (API level 18).
-     */
-    public static boolean isAtLeastJB_MR2() {
-        return sIsAtLeastJB_MR2;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least KLP
-     *  (API level 19).
-     */
-    public static boolean isAtLeastKLP() {
-        return sIsAtLeastKLP;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least L
-     *  (API level 21).
-     */
-    public static boolean isAtLeastL() {
-        return sIsAtLeastL;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least L MR1
-     *  (API level 22).
-     */
-    public static boolean isAtLeastL_MR1() {
-        return sIsAtLeastL_MR1;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least M
-     *  (API level 23).
-     */
-    public static boolean isAtLeastM() {
-        return sIsAtLeastM;
-    }
-
-    /**
-     * @return True if the version of Android that we're running on is at least N
-     *  (API level 24).
-     */
-    public static boolean isAtLeastN() {
-        return sIsAtLeastN;
-    }
-
-    /**
-     * @return The Android API version of the OS that we're currently running on.
-     */
-    public static int getApiVersion() {
-        return android.os.Build.VERSION.SDK_INT;
-    }
-
     public static boolean isSecondaryUser() {
         if (sIsSecondaryUser == null) {
             final Context context = Factory.get().getApplicationContext();
             boolean isSecondaryUser = false;
 
-            // Only check for newer devices (but not the nexus 10)
-            if (OsUtil.sIsAtLeastJB_MR1 && !"Nexus 10".equals(Build.MODEL)) {
-                final UserHandle uh = android.os.Process.myUserHandle();
-                final UserManager userManager =
-                        (UserManager) context.getSystemService(Context.USER_SERVICE);
-                if (userManager != null) {
-                    final long userSerialNumber = userManager.getSerialNumberForUser(uh);
-                    isSecondaryUser = (0 != userSerialNumber);
-                }
+            final UserHandle uh = android.os.Process.myUserHandle();
+            final UserManager userManager =
+                    (UserManager) context.getSystemService(Context.USER_SERVICE);
+            if (userManager != null) {
+                final long userSerialNumber = userManager.getSerialNumberForUser(uh);
+                isSecondaryUser = (0 != userSerialNumber);
             }
             sIsSecondaryUser = isSecondaryUser;
         }
@@ -192,20 +86,16 @@ public class OsUtil {
      * @param permission A permission from {@link android.Manifest.permission}
      */
     public static boolean hasPermission(final String permission) {
-        if (OsUtil.isAtLeastM()) {
-            // It is safe to cache the PERMISSION_GRANTED result as the process gets killed if the
-            // user revokes the permission setting. However, PERMISSION_DENIED should not be
-            // cached as the process does not get killed if the user enables the permission setting.
-            if (!sPermissions.containsKey(permission)
-                    || sPermissions.get(permission) == PackageManager.PERMISSION_DENIED) {
-                final Context context = Factory.get().getApplicationContext();
-                final int permissionState = context.checkSelfPermission(permission);
-                sPermissions.put(permission, permissionState);
-            }
-            return sPermissions.get(permission) == PackageManager.PERMISSION_GRANTED;
-        } else {
-            return true;
+        // It is safe to cache the PERMISSION_GRANTED result as the process gets killed if the
+        // user revokes the permission setting. However, PERMISSION_DENIED should not be
+        // cached as the process does not get killed if the user enables the permission setting.
+        if (!sPermissions.containsKey(permission)
+                || sPermissions.get(permission) == PackageManager.PERMISSION_DENIED) {
+            final Context context = Factory.get().getApplicationContext();
+            final int permissionState = context.checkSelfPermission(permission);
+            sPermissions.put(permission, permissionState);
         }
+        return sPermissions.get(permission) == PackageManager.PERMISSION_GRANTED;
     }
 
     /** Does the app have all the specified permissions */
diff --git a/src/com/android/messaging/util/PhoneUtils.java b/src/com/android/messaging/util/PhoneUtils.java
index 9f0fa8e..ef7aafc 100644
--- a/src/com/android/messaging/util/PhoneUtils.java
+++ b/src/com/android/messaging/util/PhoneUtils.java
@@ -17,14 +17,13 @@
 package com.android.messaging.util;
 
 import android.app.role.RoleManager;
-import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.ApplicationInfoFlags;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.database.Cursor;
-import android.net.ConnectivityManager;
 import android.provider.Settings;
 import android.provider.Telephony;
 import android.telephony.PhoneNumberUtils;
@@ -35,7 +34,6 @@ import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 
 import androidx.collection.ArrayMap;
-import androidx.core.os.BuildCompat;
 
 import com.android.messaging.Factory;
 import com.android.messaging.R;
@@ -64,7 +62,7 @@ import java.util.Locale;
  *
  * A convenient getDefault() method is provided for default subId (-1) on any platform
  */
-public abstract class PhoneUtils {
+public class PhoneUtils {
     private static final String TAG = LogUtil.BUGLE_TAG;
 
     private static final int MINIMUM_PHONE_NUMBER_LENGTH_TO_FORMAT = 6;
@@ -79,6 +77,7 @@ public abstract class PhoneUtils {
 
     protected final Context mContext;
     protected final TelephonyManager mTelephonyManager;
+    private final SubscriptionManager mSubscriptionManager;
     protected final int mSubId;
 
     public PhoneUtils(int subId) {
@@ -86,6 +85,7 @@ public abstract class PhoneUtils {
         mContext = Factory.get().getApplicationContext();
         mTelephonyManager =
                 (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
+        mSubscriptionManager = SubscriptionManager.from(Factory.get().getApplicationContext());
     }
 
     /**
@@ -93,49 +93,90 @@ public abstract class PhoneUtils {
      *
      * @return the country code on the SIM
      */
-    public abstract String getSimCountry();
+    public String getSimCountry() {
+        final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+        if (subInfo != null) {
+            final String country = subInfo.getCountryIso();
+            if (TextUtils.isEmpty(country)) {
+                return null;
+            }
+            return country.toUpperCase();
+        }
+        return null;
+    }
 
     /**
      * Get number of SIM slots
      *
      * @return the SIM slot count
      */
-    public abstract int getSimSlotCount();
+    public int getSimSlotCount() {
+        return mSubscriptionManager.getActiveSubscriptionInfoCountMax();
+    }
 
     /**
      * Get SIM's carrier name
      *
      * @return the carrier name of the SIM
      */
-    public abstract String getCarrierName();
+    public String getCarrierName() {
+        final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+        if (subInfo != null) {
+            final CharSequence displayName = subInfo.getDisplayName();
+            if (!TextUtils.isEmpty(displayName)) {
+                return displayName.toString();
+            }
+            final CharSequence carrierName = subInfo.getCarrierName();
+            if (carrierName != null) {
+                return carrierName.toString();
+            }
+        }
+        return null;
+    }
 
     /**
      * Check if there is SIM inserted on the device
      *
      * @return true if there is SIM inserted, false otherwise
      */
-    public abstract boolean hasSim();
+    public boolean hasSim() {
+        return mSubscriptionManager.getActiveSubscriptionInfoCount() > 0;
+    }
 
     /**
      * Check if the SIM is roaming
      *
      * @return true if the SIM is in romaing state, false otherwise
      */
-    public abstract boolean isRoaming();
+    public boolean isRoaming() {
+        return mSubscriptionManager.isNetworkRoaming(mSubId);
+    }
 
     /**
      * Get the MCC and MNC in integer of the SIM's provider
      *
      * @return an array of two ints, [0] is the MCC code and [1] is the MNC code
      */
-    public abstract int[] getMccMnc();
+    public int[] getMccMnc() {
+        int mcc = 0;
+        int mnc = 0;
+        final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+        if (subInfo != null) {
+            mcc = subInfo.getMcc();
+            mnc = subInfo.getMnc();
+        }
+        return new int[]{mcc, mnc};
+    }
 
     /**
      * Get the mcc/mnc string
      *
      * @return the text of mccmnc string
      */
-    public abstract String getSimOperatorNumeric();
+    public String getSimOperatorNumeric() {
+        // For L_MR1 we return the canonicalized (xxxxxx) string
+        return getMccMncString(getMccMnc());
+    }
 
     /**
      * Get the SIM's self raw number, i.e. not canonicalized
@@ -144,7 +185,25 @@ public abstract class PhoneUtils {
      * @return the original self number
      * @throws IllegalStateException if no active subscription on L-MR1+
      */
-    public abstract String getSelfRawNumber(final boolean allowOverride);
+    public String getSelfRawNumber(final boolean allowOverride) {
+        if (allowOverride) {
+            final String userDefinedNumber = getNumberFromPrefs(mContext, mSubId);
+            if (!TextUtils.isEmpty(userDefinedNumber)) {
+                return userDefinedNumber;
+            }
+        }
+
+        final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+        if (subInfo != null) {
+            String phoneNumber = subInfo.getNumber();
+            if (TextUtils.isEmpty(phoneNumber) && LogUtil.isLoggable(TAG, LogUtil.DEBUG)) {
+                LogUtil.d(TAG, "SubscriptionInfo phone number for self is empty!");
+            }
+            return phoneNumber;
+        }
+        LogUtil.w(TAG, "PhoneUtils.getSelfRawNumber: subInfo is null for " + mSubId);
+        throw new IllegalStateException("No active subscription");
+    }
 
     /**
      * Returns the "effective" subId, or the subId used in the context of actual messages,
@@ -159,31 +218,49 @@ public abstract class PhoneUtils {
      * @param subId The input subId
      * @return the real subId if we can convert
      */
-    public abstract int getEffectiveSubId(int subId);
+    public int getEffectiveSubId(int subId) {
+        if (subId == ParticipantData.DEFAULT_SELF_SUB_ID) {
+            return getDefaultSmsSubscriptionId();
+        }
+        return subId;
+    }
 
     /**
      * Returns the number of active subscriptions in the device.
      */
-    public abstract int getActiveSubscriptionCount();
+    public int getActiveSubscriptionCount() {
+        return mSubscriptionManager.getActiveSubscriptionInfoCount();
+    }
 
     /**
      * Get {@link SmsManager} instance
      *
      * @return the relevant SmsManager instance based on OS version and subId
      */
-    public abstract SmsManager getSmsManager();
+    public SmsManager getSmsManager() {
+        return SmsManager.getSmsManagerForSubscriptionId(mSubId);
+    }
 
     /**
      * Get the default SMS subscription id
      *
      * @return the default sub ID
      */
-    public abstract int getDefaultSmsSubscriptionId();
+    public int getDefaultSmsSubscriptionId() {
+        final int systemDefaultSubId = SmsManager.getDefaultSmsSubscriptionId();
+        if (systemDefaultSubId < 0) {
+            // Always use -1 for any negative subId from system
+            return ParticipantData.DEFAULT_SELF_SUB_ID;
+        }
+        return systemDefaultSubId;
+    }
 
     /**
      * Returns if there's currently a system default SIM selected for sending SMS.
      */
-    public abstract boolean getHasPreferredSmsSim();
+    public boolean getHasPreferredSmsSim() {
+        return getDefaultSmsSubscriptionId() != ParticipantData.DEFAULT_SELF_SUB_ID;
+    }
 
     /**
      * For L_MR1, system may return a negative subId. Convert this into our own
@@ -195,7 +272,23 @@ public abstract class PhoneUtils {
      * @param extraName The name of the sub id extra
      * @return the subId that is valid and meaningful for the app
      */
-    public abstract int getEffectiveIncomingSubIdFromSystem(Intent intent, String extraName);
+    public int getEffectiveIncomingSubIdFromSystem(Intent intent, String extraName) {
+        return getEffectiveIncomingSubIdFromSystem(intent.getIntExtra(extraName,
+                ParticipantData.DEFAULT_SELF_SUB_ID));
+    }
+
+    private int getEffectiveIncomingSubIdFromSystem(int subId) {
+        if (subId < 0) {
+            if (mSubscriptionManager.getActiveSubscriptionInfoCount() > 1) {
+                // For multi-SIM device, we can not decide which SIM to use if system
+                // does not know either. So just make it the invalid sub id.
+                return ParticipantData.DEFAULT_SELF_SUB_ID;
+            }
+            // For single-SIM device, it must come from the only SIM we have
+            return getDefaultSmsSubscriptionId();
+        }
+        return subId;
+    }
 
     /**
      * Get the subscription_id column value from a telephony provider cursor
@@ -204,438 +297,107 @@ public abstract class PhoneUtils {
      * @param subIdIndex The index of the subId column in the cursor
      * @return the subscription_id column value from the cursor
      */
-    public abstract int getSubIdFromTelephony(Cursor cursor, int subIdIndex);
+    public int getSubIdFromTelephony(Cursor cursor, int subIdIndex) {
+        return getEffectiveIncomingSubIdFromSystem(cursor.getInt(subIdIndex));
+    }
 
     /**
      * Check if data roaming is enabled
      *
      * @return true if data roaming is enabled, false otherwise
      */
-    public abstract boolean isDataRoamingEnabled();
+    public boolean isDataRoamingEnabled() {
+        final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+        if (subInfo == null) {
+            // There is nothing we can do if system give us empty sub info
+            LogUtil.e(TAG, "PhoneUtils.isDataRoamingEnabled: system return empty sub info for "
+                    + mSubId);
+            return false;
+        }
+        return subInfo.getDataRoaming() != SubscriptionManager.DATA_ROAMING_DISABLE;
+    }
 
     /**
      * Check if mobile data is enabled
      *
      * @return true if mobile data is enabled, false otherwise
      */
-    public abstract boolean isMobileDataEnabled();
+    public boolean isMobileDataEnabled() {
+        boolean mobileDataEnabled = false;
+        try {
+            final Class cmClass = mTelephonyManager.getClass();
+            final Method method = cmClass.getDeclaredMethod("getDataEnabled", Integer.TYPE);
+            method.setAccessible(true); // Make the method callable
+            // get the setting for "mobile data"
+            mobileDataEnabled = (Boolean) method.invoke(
+                    mTelephonyManager, Integer.valueOf(mSubId));
+        } catch (final Exception e) {
+            LogUtil.e(TAG, "PhoneUtil.isMobileDataEnabled: system api not found", e);
+        }
+        return mobileDataEnabled;
+
+    }
 
     /**
      * Get the set of self phone numbers, all normalized
      *
      * @return the set of normalized self phone numbers
      */
-    public abstract HashSet<String> getNormalizedSelfNumbers();
-
-    /**
-     * This interface packages methods should only compile on L_MR1.
-     * This is needed to make unit tests happy when mockito tries to
-     * mock these methods. Calling on these methods on L_MR1 requires
-     * an extra invocation of toMr1().
-     */
-    public interface LMr1 {
-        /**
-         * Get this SIM's information. Only applies to L_MR1 above
-         *
-         * @return the subscription info of the SIM
-         */
-        public abstract SubscriptionInfo getActiveSubscriptionInfo();
-
-        /**
-         * Get the list of active SIMs in system. Only applies to L_MR1 above
-         *
-         * @return the list of subscription info for all inserted SIMs
-         */
-        public abstract List<SubscriptionInfo> getActiveSubscriptionInfoList();
-
-        /**
-         * Register subscription change listener. Only applies to L_MR1 above
-         *
-         * @param listener The listener to register
-         */
-        public abstract void registerOnSubscriptionsChangedListener(
-                SubscriptionManager.OnSubscriptionsChangedListener listener);
+    public HashSet<String> getNormalizedSelfNumbers() {
+        final HashSet<String> numbers = new HashSet<>();
+        for (SubscriptionInfo info : getActiveSubscriptionInfoList()) {
+            numbers.add(PhoneUtils.get(info.getSubscriptionId()).getCanonicalForSelf(
+                    true/*allowOverride*/));
+        }
+        return numbers;
     }
 
     /**
-     * The PhoneUtils class for pre L_MR1
+     * Get this SIM's information. Only applies to L_MR1 above
+     *
+     * @return the subscription info of the SIM
      */
-    public static class PhoneUtilsPreLMR1 extends PhoneUtils {
-        private final ConnectivityManager mConnectivityManager;
-
-        public PhoneUtilsPreLMR1() {
-            super(ParticipantData.DEFAULT_SELF_SUB_ID);
-            mConnectivityManager =
-                    (ConnectivityManager) mContext.getSystemService(Context.CONNECTIVITY_SERVICE);
-        }
-
-        @Override
-        public String getSimCountry() {
-            final String country = mTelephonyManager.getSimCountryIso();
-            if (TextUtils.isEmpty(country)) {
-                return null;
-            }
-            return country.toUpperCase();
-        }
-
-        @Override
-        public int getSimSlotCount() {
-            // Don't support MSIM pre-L_MR1
-            return 1;
-        }
-
-        @Override
-        public String getCarrierName() {
-            return mTelephonyManager.getNetworkOperatorName();
-        }
-
-        @Override
-        public boolean hasSim() {
-            return mTelephonyManager.getSimState() != TelephonyManager.SIM_STATE_ABSENT;
-        }
-
-        @Override
-        public boolean isRoaming() {
-            return mTelephonyManager.isNetworkRoaming();
-        }
-
-        @Override
-        public int[] getMccMnc() {
-            final String mccmnc = mTelephonyManager.getSimOperator();
-            int mcc = 0;
-            int mnc = 0;
-            try {
-                mcc = Integer.parseInt(mccmnc.substring(0, 3));
-                mnc = Integer.parseInt(mccmnc.substring(3));
-            } catch (Exception e) {
-                LogUtil.w(TAG, "PhoneUtils.getMccMnc: invalid string " + mccmnc, e);
-            }
-            return new int[]{mcc, mnc};
-        }
-
-        @Override
-        public String getSimOperatorNumeric() {
-            return mTelephonyManager.getSimOperator();
-        }
-
-        @Override
-        public String getSelfRawNumber(final boolean allowOverride) {
-            if (allowOverride) {
-                final String userDefinedNumber = getNumberFromPrefs(mContext,
-                        ParticipantData.DEFAULT_SELF_SUB_ID);
-                if (!TextUtils.isEmpty(userDefinedNumber)) {
-                    return userDefinedNumber;
-                }
-            }
-            return mTelephonyManager.getLine1Number();
-        }
-
-        @Override
-        public int getEffectiveSubId(int subId) {
-            Assert.equals(ParticipantData.DEFAULT_SELF_SUB_ID, subId);
-            return ParticipantData.DEFAULT_SELF_SUB_ID;
-        }
-
-        @Override
-        public SmsManager getSmsManager() {
-            return SmsManager.getDefault();
-        }
-
-        @Override
-        public int getDefaultSmsSubscriptionId() {
-            Assert.fail("PhoneUtils.getDefaultSmsSubscriptionId(): not supported before L MR1");
-            return ParticipantData.DEFAULT_SELF_SUB_ID;
-        }
-
-        @Override
-        public boolean getHasPreferredSmsSim() {
-            // SIM selection is not supported pre-L_MR1.
-            return true;
-        }
-
-        @Override
-        public int getActiveSubscriptionCount() {
-            return hasSim() ? 1 : 0;
-        }
-
-        @Override
-        public int getEffectiveIncomingSubIdFromSystem(Intent intent, String extraName) {
-            // Pre-L_MR1 always returns the default id
-            return ParticipantData.DEFAULT_SELF_SUB_ID;
-        }
-
-        @Override
-        public int getSubIdFromTelephony(Cursor cursor, int subIdIndex) {
-            // No subscription_id column before L_MR1
-            return ParticipantData.DEFAULT_SELF_SUB_ID;
-        }
-
-        @Override
-        @SuppressWarnings("deprecation")
-        public boolean isDataRoamingEnabled() {
-            if (BuildCompat.isAtLeastT()) {
-                return mTelephonyManager.isDataRoamingEnabled();
-            }
-            boolean dataRoamingEnabled = false;
-            final ContentResolver cr = mContext.getContentResolver();
-            if (OsUtil.isAtLeastJB_MR1()) {
-                dataRoamingEnabled =
-                        (Settings.Global.getInt(cr, Settings.Global.DATA_ROAMING, 0) != 0);
-            } else {
-                dataRoamingEnabled =
-                        (Settings.System.getInt(cr, Settings.System.DATA_ROAMING, 0) != 0);
-            }
-            return dataRoamingEnabled;
-        }
-
-        @Override
-        public boolean isMobileDataEnabled() {
-            boolean mobileDataEnabled = false;
-            try {
-                final Class cmClass = mConnectivityManager.getClass();
-                final Method method = cmClass.getDeclaredMethod("getMobileDataEnabled");
-                method.setAccessible(true); // Make the method callable
-                // get the setting for "mobile data"
-                mobileDataEnabled = (Boolean) method.invoke(mConnectivityManager);
-            } catch (final Exception e) {
-                LogUtil.e(TAG, "PhoneUtil.isMobileDataEnabled: system api not found", e);
-            }
-            return mobileDataEnabled;
-        }
-
-        @Override
-        public HashSet<String> getNormalizedSelfNumbers() {
-            final HashSet<String> numbers = new HashSet<>();
-            numbers.add(getCanonicalForSelf(true/*allowOverride*/));
-            return numbers;
-        }
-    }
-
-    /**
-     * The PhoneUtils class for L_MR1
-     */
-    public static class PhoneUtilsLMR1 extends PhoneUtils implements LMr1 {
-        private final SubscriptionManager mSubscriptionManager;
-
-        public PhoneUtilsLMR1(final int subId) {
-            super(subId);
-            mSubscriptionManager = SubscriptionManager.from(Factory.get().getApplicationContext());
-        }
-
-        @Override
-        public String getSimCountry() {
-            final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
-            if (subInfo != null) {
-                final String country = subInfo.getCountryIso();
-                if (TextUtils.isEmpty(country)) {
-                    return null;
-                }
-                return country.toUpperCase();
-            }
-            return null;
-        }
-
-        @Override
-        public int getSimSlotCount() {
-            return mSubscriptionManager.getActiveSubscriptionInfoCountMax();
-        }
-
-        @Override
-        public String getCarrierName() {
-            final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
-            if (subInfo != null) {
-                final CharSequence displayName = subInfo.getDisplayName();
-                if (!TextUtils.isEmpty(displayName)) {
-                    return displayName.toString();
-                }
-                final CharSequence carrierName = subInfo.getCarrierName();
-                if (carrierName != null) {
-                    return carrierName.toString();
-                }
-            }
-            return null;
-        }
-
-        @Override
-        public boolean hasSim() {
-            return mSubscriptionManager.getActiveSubscriptionInfoCount() > 0;
-        }
-
-        @Override
-        public boolean isRoaming() {
-            return mSubscriptionManager.isNetworkRoaming(mSubId);
-        }
-
-        @Override
-        public int[] getMccMnc() {
-            int mcc = 0;
-            int mnc = 0;
-            final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
-            if (subInfo != null) {
-                mcc = subInfo.getMcc();
-                mnc = subInfo.getMnc();
-            }
-            return new int[]{mcc, mnc};
-        }
-
-        @Override
-        public String getSimOperatorNumeric() {
-            // For L_MR1 we return the canonicalized (xxxxxx) string
-            return getMccMncString(getMccMnc());
-        }
-
-        @Override
-        public String getSelfRawNumber(final boolean allowOverride) {
-            if (allowOverride) {
-                final String userDefinedNumber = getNumberFromPrefs(mContext, mSubId);
-                if (!TextUtils.isEmpty(userDefinedNumber)) {
-                    return userDefinedNumber;
-                }
-            }
-
-            final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
-            if (subInfo != null) {
-                String phoneNumber = subInfo.getNumber();
-                if (TextUtils.isEmpty(phoneNumber) && LogUtil.isLoggable(TAG, LogUtil.DEBUG)) {
-                    LogUtil.d(TAG, "SubscriptionInfo phone number for self is empty!");
-                }
-                return phoneNumber;
-            }
-            LogUtil.w(TAG, "PhoneUtils.getSelfRawNumber: subInfo is null for " + mSubId);
-            throw new IllegalStateException("No active subscription");
-        }
-
-        @Override
-        public SubscriptionInfo getActiveSubscriptionInfo() {
-            try {
-                final SubscriptionInfo subInfo =
-                        mSubscriptionManager.getActiveSubscriptionInfo(mSubId);
-                if (subInfo == null) {
-                    if (LogUtil.isLoggable(TAG, LogUtil.DEBUG)) {
-                        // This is possible if the sub id is no longer available.
-                        LogUtil.d(TAG, "PhoneUtils.getActiveSubscriptionInfo(): empty sub info for "
-                                + mSubId);
-                    }
-                }
-                return subInfo;
-            } catch (Exception e) {
-                LogUtil.e(TAG, "PhoneUtils.getActiveSubscriptionInfo: system exception for "
-                        + mSubId, e);
-            }
-            return null;
-        }
-
-        @Override
-        public List<SubscriptionInfo> getActiveSubscriptionInfoList() {
-            final List<SubscriptionInfo> subscriptionInfos =
-                    mSubscriptionManager.getActiveSubscriptionInfoList();
-            if (subscriptionInfos != null) {
-                return subscriptionInfos;
-            }
-            return EMPTY_SUBSCRIPTION_LIST;
-        }
-
-        @Override
-        public int getEffectiveSubId(int subId) {
-            if (subId == ParticipantData.DEFAULT_SELF_SUB_ID) {
-                return getDefaultSmsSubscriptionId();
-            }
-            return subId;
-        }
-
-        @Override
-        public void registerOnSubscriptionsChangedListener(
-                SubscriptionManager.OnSubscriptionsChangedListener listener) {
-            mSubscriptionManager.addOnSubscriptionsChangedListener(listener);
-        }
-
-        @Override
-        public SmsManager getSmsManager() {
-            return SmsManager.getSmsManagerForSubscriptionId(mSubId);
-        }
-
-        @Override
-        public int getDefaultSmsSubscriptionId() {
-            final int systemDefaultSubId = SmsManager.getDefaultSmsSubscriptionId();
-            if (systemDefaultSubId < 0) {
-                // Always use -1 for any negative subId from system
-                return ParticipantData.DEFAULT_SELF_SUB_ID;
-            }
-            return systemDefaultSubId;
-        }
-
-        @Override
-        public boolean getHasPreferredSmsSim() {
-            return getDefaultSmsSubscriptionId() != ParticipantData.DEFAULT_SELF_SUB_ID;
-        }
-
-        @Override
-        public int getActiveSubscriptionCount() {
-            return mSubscriptionManager.getActiveSubscriptionInfoCount();
-        }
-
-        @Override
-        public int getEffectiveIncomingSubIdFromSystem(Intent intent, String extraName) {
-            return getEffectiveIncomingSubIdFromSystem(intent.getIntExtra(extraName,
-                    ParticipantData.DEFAULT_SELF_SUB_ID));
-        }
-
-        private int getEffectiveIncomingSubIdFromSystem(int subId) {
-            if (subId < 0) {
-                if (mSubscriptionManager.getActiveSubscriptionInfoCount() > 1) {
-                    // For multi-SIM device, we can not decide which SIM to use if system
-                    // does not know either. So just make it the invalid sub id.
-                    return ParticipantData.DEFAULT_SELF_SUB_ID;
-                }
-                // For single-SIM device, it must come from the only SIM we have
-                return getDefaultSmsSubscriptionId();
-            }
-            return subId;
-        }
-
-        @Override
-        public int getSubIdFromTelephony(Cursor cursor, int subIdIndex) {
-            return getEffectiveIncomingSubIdFromSystem(cursor.getInt(subIdIndex));
-        }
-
-        @Override
-        public boolean isDataRoamingEnabled() {
-            final SubscriptionInfo subInfo = getActiveSubscriptionInfo();
+    public SubscriptionInfo getActiveSubscriptionInfo() {
+        try {
+            final SubscriptionInfo subInfo =
+                    mSubscriptionManager.getActiveSubscriptionInfo(mSubId);
             if (subInfo == null) {
-                // There is nothing we can do if system give us empty sub info
-                LogUtil.e(TAG, "PhoneUtils.isDataRoamingEnabled: system return empty sub info for "
-                        + mSubId);
-                return false;
+                if (LogUtil.isLoggable(TAG, LogUtil.DEBUG)) {
+                    // This is possible if the sub id is no longer available.
+                    LogUtil.d(TAG, "PhoneUtils.getActiveSubscriptionInfo(): empty sub info for "
+                            + mSubId);
+                }
             }
-            return subInfo.getDataRoaming() != SubscriptionManager.DATA_ROAMING_DISABLE;
+            return subInfo;
+        } catch (Exception e) {
+            LogUtil.e(TAG, "PhoneUtils.getActiveSubscriptionInfo: system exception for "
+                    + mSubId, e);
         }
+        return null;
+    }
 
-        @Override
-        public boolean isMobileDataEnabled() {
-            boolean mobileDataEnabled = false;
-            try {
-                final Class cmClass = mTelephonyManager.getClass();
-                final Method method = cmClass.getDeclaredMethod("getDataEnabled", Integer.TYPE);
-                method.setAccessible(true); // Make the method callable
-                // get the setting for "mobile data"
-                mobileDataEnabled = (Boolean) method.invoke(
-                        mTelephonyManager, Integer.valueOf(mSubId));
-            } catch (final Exception e) {
-                LogUtil.e(TAG, "PhoneUtil.isMobileDataEnabled: system api not found", e);
-            }
-            return mobileDataEnabled;
-
+    /**
+     * Get the list of active SIMs in system. Only applies to L_MR1 above
+     *
+     * @return the list of subscription info for all inserted SIMs
+     */
+    public List<SubscriptionInfo> getActiveSubscriptionInfoList() {
+        final List<SubscriptionInfo> subscriptionInfos =
+                mSubscriptionManager.getActiveSubscriptionInfoList();
+        if (subscriptionInfos != null) {
+            return subscriptionInfos;
         }
+        return EMPTY_SUBSCRIPTION_LIST;
+    }
 
-        @Override
-        public HashSet<String> getNormalizedSelfNumbers() {
-            final HashSet<String> numbers = new HashSet<>();
-            for (SubscriptionInfo info : getActiveSubscriptionInfoList()) {
-                numbers.add(PhoneUtils.get(info.getSubscriptionId()).getCanonicalForSelf(
-                        true/*allowOverride*/));
-            }
-            return numbers;
-        }
+    /**
+     * Register subscription change listener. Only applies to L_MR1 above
+     *
+     * @param listener The listener to register
+     */
+    public void registerOnSubscriptionsChangedListener(
+            SubscriptionManager.OnSubscriptionsChangedListener listener) {
+        mSubscriptionManager.addOnSubscriptionsChangedListener(listener);
     }
 
     /**
@@ -659,15 +421,6 @@ public abstract class PhoneUtils {
         return Factory.get().getPhoneUtils(subId);
     }
 
-    public LMr1 toLMr1() {
-        if (OsUtil.isAtLeastL_MR1()) {
-            return (LMr1) this;
-        } else {
-            Assert.fail("PhoneUtils.toLMr1(): invalid OS version");
-            return null;
-        }
-    }
-
     /**
      * Check if this device supports SMS
      *
@@ -897,12 +650,9 @@ public abstract class PhoneUtils {
      * - On JB (and below) this always returns true, since the setting was added in KLP.
      */
     public boolean isDefaultSmsApp() {
-        if (OsUtil.isAtLeastKLP()) {
-            RoleManager roleManager = mContext.getSystemService(RoleManager.class);
-            return roleManager.isRoleAvailable(RoleManager.ROLE_SMS)
-                    && roleManager.isRoleHeld(RoleManager.ROLE_SMS);
-        }
-        return true;
+        RoleManager roleManager = mContext.getSystemService(RoleManager.class);
+        return roleManager.isRoleAvailable(RoleManager.ROLE_SMS)
+                && roleManager.isRoleHeld(RoleManager.ROLE_SMS);
     }
 
     /**
@@ -911,10 +661,7 @@ public abstract class PhoneUtils {
      * @return the package name of default SMS app
      */
     public String getDefaultSmsApp() {
-        if (OsUtil.isAtLeastKLP()) {
-            return Telephony.Sms.getDefaultSmsPackage(mContext);
-        }
-        return null;
+        return Telephony.Sms.getDefaultSmsPackage(mContext);
     }
 
     /**
@@ -931,15 +678,14 @@ public abstract class PhoneUtils {
      * an error or there is no default app (e.g. JB and below).
      */
     public String getDefaultSmsAppLabel() {
-        if (OsUtil.isAtLeastKLP()) {
-            final String packageName = Telephony.Sms.getDefaultSmsPackage(mContext);
-            final PackageManager pm = mContext.getPackageManager();
-            try {
-                final ApplicationInfo appInfo = pm.getApplicationInfo(packageName, 0);
-                return pm.getApplicationLabel(appInfo).toString();
-            } catch (NameNotFoundException e) {
-                // Fall through and return empty string
-            }
+        final String packageName = Telephony.Sms.getDefaultSmsPackage(mContext);
+        final PackageManager pm = mContext.getPackageManager();
+        try {
+            final ApplicationInfo appInfo = pm.getApplicationInfo(packageName,
+                    ApplicationInfoFlags.of(0));
+            return pm.getApplicationLabel(appInfo).toString();
+        } catch (NameNotFoundException e) {
+            // Fall through and return empty string
         }
         return "";
     }
@@ -949,15 +695,9 @@ public abstract class PhoneUtils {
      *
      * @return true if enabled.
      */
-    @SuppressWarnings("deprecation")
     public boolean isAirplaneModeOn() {
-        if (OsUtil.isAtLeastJB_MR1()) {
-            return Settings.Global.getInt(mContext.getContentResolver(),
-                    Settings.Global.AIRPLANE_MODE_ON, 0) != 0;
-        } else {
-            return Settings.System.getInt(mContext.getContentResolver(),
-                    Settings.System.AIRPLANE_MODE_ON, 0) != 0;
-        }
+        return Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.AIRPLANE_MODE_ON, 0) != 0;
     }
 
     public static String getMccMncString(int[] mccmnc) {
@@ -995,14 +735,10 @@ public abstract class PhoneUtils {
      * @param runnable a {@link SubscriptionRunnable} for performing work on each subscription.
      */
     public static void forEachActiveSubscription(final SubscriptionRunnable runnable) {
-        if (OsUtil.isAtLeastL_MR1()) {
-            final List<SubscriptionInfo> subscriptionList =
-                    getDefault().toLMr1().getActiveSubscriptionInfoList();
-            for (final SubscriptionInfo subscriptionInfo : subscriptionList) {
-                runnable.runForSubscription(subscriptionInfo.getSubscriptionId());
-            }
-        } else {
-            runnable.runForSubscription(ParticipantData.DEFAULT_SELF_SUB_ID);
+        final List<SubscriptionInfo> subscriptionList =
+                getDefault().getActiveSubscriptionInfoList();
+        for (final SubscriptionInfo subscriptionInfo : subscriptionList) {
+            runnable.runForSubscription(subscriptionInfo.getSubscriptionId());
         }
     }
 
diff --git a/src/com/android/messaging/util/Trace.java b/src/com/android/messaging/util/Trace.java
index 69910f7..14b4d12 100644
--- a/src/com/android/messaging/util/Trace.java
+++ b/src/com/android/messaging/util/Trace.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,20 +17,10 @@
 
 package com.android.messaging.util;
 
-
-import android.annotation.TargetApi;
-import android.os.Build;
-
 /**
  * Helper class for systrace (see http://developer.android.com/tools/help/systrace.html).<p>
  * To enable, set log.tag.Bugle_Trace (defined by {@link #TAG} to VERBOSE before
  * the process starts.<p>
- * Note that this will run only on JBMR2 or later; on earlier platforms or if the log
- * tag isn't set, calls to {@link #beginSection(String)} or {@link #endSection()} are no-ops. <p>
- * Internally, calls dispatch to either a class that actually does work or a class that doesn't.
- * This avoids Dalvik complaining when it loads the class on earlier platforms that the
- * opcodes aren't available, and, according to the Dalvik team, using vtable dispatching for
- * something like this should be faster than if (OsUtil.isAtLeast...()) on each call.
  */
 public final class Trace {
     private static final String TAG = "Bugle_Trace";
@@ -44,8 +35,7 @@ public final class Trace {
     static {
         // Use android.util.Log instead of LogUtil here to avoid pulling in Gservices
         // too early in app startup.
-        if (OsUtil.isAtLeastJB_MR2() &&
-                android.util.Log.isLoggable(TAG, android.util.Log.VERBOSE)) {
+        if (android.util.Log.isLoggable(TAG, android.util.Log.VERBOSE)) {
             sTrace = new TraceJBMR2();
         } else {
             sTrace = new TraceShim();
@@ -87,7 +77,6 @@ public final class Trace {
     /**
      * Internal class that we use if we really did enable tracing.
      */
-    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
     private static final class TraceJBMR2 extends AbstractTrace {
         @Override
         void beginSection(String sectionName) {
diff --git a/src/com/android/messaging/util/UiUtils.java b/src/com/android/messaging/util/UiUtils.java
index d77e945..8f483fd 100644
--- a/src/com/android/messaging/util/UiUtils.java
+++ b/src/com/android/messaging/util/UiUtils.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2024 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -261,16 +262,14 @@ public class UiUtils {
     }
 
     public static void setStatusBarColor(final Activity activity, final int color) {
-        if (OsUtil.isAtLeastL()) {
-            // To achieve the appearance of an 80% opacity blend against a black background,
-            // each color channel is reduced in value by 20%.
-            final int blendedRed = (int) Math.floor(0.8 * Color.red(color));
-            final int blendedGreen = (int) Math.floor(0.8 * Color.green(color));
-            final int blendedBlue = (int) Math.floor(0.8 * Color.blue(color));
+        // To achieve the appearance of an 80% opacity blend against a black background,
+        // each color channel is reduced in value by 20%.
+        final int blendedRed = (int) Math.floor(0.8 * Color.red(color));
+        final int blendedGreen = (int) Math.floor(0.8 * Color.green(color));
+        final int blendedBlue = (int) Math.floor(0.8 * Color.blue(color));
 
-            activity.getWindow().setStatusBarColor(
-                    Color.rgb(blendedRed, blendedGreen, blendedBlue));
-        }
+        activity.getWindow().setStatusBarColor(
+                Color.rgb(blendedRed, blendedGreen, blendedBlue));
     }
 
     public static void lockOrientation(final Activity activity) {
@@ -301,16 +300,8 @@ public class UiUtils {
         activity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);
     }
 
-    public static int getPaddingStart(final View view) {
-        return OsUtil.isAtLeastJB_MR1() ? view.getPaddingStart() : view.getPaddingLeft();
-    }
-
-    public static int getPaddingEnd(final View view) {
-        return OsUtil.isAtLeastJB_MR1() ? view.getPaddingEnd() : view.getPaddingRight();
-    }
-
     public static boolean isRtlMode() {
-        return OsUtil.isAtLeastJB_MR2() && Factory.get().getApplicationContext().getResources()
+        return Factory.get().getApplicationContext().getResources()
                 .getConfiguration().getLayoutDirection() == View.LAYOUT_DIRECTION_RTL;
     }
 
diff --git a/src/com/android/messaging/widget/BaseWidgetProvider.java b/src/com/android/messaging/widget/BaseWidgetProvider.java
index 6632c5f..07730ed 100644
--- a/src/com/android/messaging/widget/BaseWidgetProvider.java
+++ b/src/com/android/messaging/widget/BaseWidgetProvider.java
@@ -36,7 +36,6 @@ public abstract class BaseWidgetProvider extends AppWidgetProvider {
     public static final int SIZE_LARGE  = 0;    // undefined == 0, which is the default, large
     public static final int SIZE_SMALL  = 1;
     public static final int SIZE_MEDIUM = 2;
-    public static final int SIZE_PRE_JB = 3;
 
     /**
      * Update all widgets in the list
diff --git a/src/com/android/messaging/widget/WidgetConversationListService.java b/src/com/android/messaging/widget/WidgetConversationListService.java
index 023c56d..1eb646b 100644
--- a/src/com/android/messaging/widget/WidgetConversationListService.java
+++ b/src/com/android/messaging/widget/WidgetConversationListService.java
@@ -43,7 +43,6 @@ import com.android.messaging.ui.conversationlist.ConversationListItemView;
 import com.android.messaging.util.ContentType;
 import com.android.messaging.util.Dates;
 import com.android.messaging.util.LogUtil;
-import com.android.messaging.util.OsUtil;
 import com.android.messaging.util.PhoneUtils;
 
 public class WidgetConversationListService extends RemoteViewsService {
@@ -128,19 +127,15 @@ public class WidgetConversationListService extends RemoteViewsService {
 
                 // Avatar
                 boolean includeAvatar;
-                if (OsUtil.isAtLeastJB()) {
-                    final Bundle options = mAppWidgetManager.getAppWidgetOptions(mAppWidgetId);
-                    if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
-                        LogUtil.v(TAG, "getViewAt BugleWidgetProvider.WIDGET_SIZE_KEY: " +
-                                options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY));
-                    }
-
-                    includeAvatar = options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY) ==
-                            BugleWidgetProvider.SIZE_LARGE;
-                } else {
-                    includeAvatar = true;;
+                final Bundle options = mAppWidgetManager.getAppWidgetOptions(mAppWidgetId);
+                if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
+                    LogUtil.v(TAG, "getViewAt BugleWidgetProvider.WIDGET_SIZE_KEY: " +
+                            options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY));
                 }
 
+                includeAvatar = options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY) ==
+                        BugleWidgetProvider.SIZE_LARGE;
+
                 // Show the avatar when grande size, otherwise hide it.
                 remoteViews.setViewVisibility(R.id.avatarView, includeAvatar ?
                         View.VISIBLE : View.GONE);
diff --git a/src/com/android/messaging/widget/WidgetConversationService.java b/src/com/android/messaging/widget/WidgetConversationService.java
index 5b8587b..fa7d3ef 100644
--- a/src/com/android/messaging/widget/WidgetConversationService.java
+++ b/src/com/android/messaging/widget/WidgetConversationService.java
@@ -179,9 +179,7 @@ public class WidgetConversationService extends RemoteViewsService {
                 if (message.hasAttachments()) {
                     final List<MessagePartData> attachments = message.getAttachments();
                     for (MessagePartData part : attachments) {
-                        final boolean videoWithThumbnail = part.isVideo()
-                                && (VideoThumbnailRequest.shouldShowIncomingVideoThumbnails()
-                                || !message.getIsIncoming());
+                        final boolean videoWithThumbnail = part.isVideo();
                         if (part.isImage() || videoWithThumbnail) {
                             final Uri uri = part.getContentUri();
                             remoteViews.setViewVisibility(R.id.attachmentFrame, View.VISIBLE);
@@ -215,20 +213,15 @@ public class WidgetConversationService extends RemoteViewsService {
                         intent);
 
                 // Avatar
-                boolean includeAvatar;
-                if (OsUtil.isAtLeastJB()) {
-                    final Bundle options = mAppWidgetManager.getAppWidgetOptions(mAppWidgetId);
-                    if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
-                        LogUtil.v(TAG, "getViewAt BugleWidgetProvider.WIDGET_SIZE_KEY: " +
-                                options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY));
-                    }
-
-                    includeAvatar = options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY)
-                            == BugleWidgetProvider.SIZE_LARGE;
-                } else {
-                    includeAvatar = true;
+                final Bundle options = mAppWidgetManager.getAppWidgetOptions(mAppWidgetId);
+                if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
+                    LogUtil.v(TAG, "getViewAt BugleWidgetProvider.WIDGET_SIZE_KEY: " +
+                            options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY));
                 }
 
+                boolean includeAvatar = options.getInt(BugleWidgetProvider.WIDGET_SIZE_KEY)
+                        == BugleWidgetProvider.SIZE_LARGE;
+
                 // Show the avatar (and shadow) when grande size, otherwise hide it.
                 remoteViews.setViewVisibility(R.id.avatarView, includeAvatar ?
                         View.VISIBLE : View.GONE);