diff --git a/flags/telecom_callaudioroutestatemachine_flags.aconfig b/flags/telecom_callaudioroutestatemachine_flags.aconfig
index ab7ec88..28071fc 100644
--- a/flags/telecom_callaudioroutestatemachine_flags.aconfig
+++ b/flags/telecom_callaudioroutestatemachine_flags.aconfig
@@ -48,3 +48,10 @@
   description: "Protect set/clear communication device operation with lock to avoid race condition."
   bug: "303001133"
 }
+
+flag {
+  name: "update_route_mask_when_bt_connected"
+  namespace: "telecom"
+  description: "Update supported route mask when Bluetooth devices audio connected."
+  bug: "301695370"
+}
diff --git a/src/com/android/server/telecom/CallAudioRouteStateMachine.java b/src/com/android/server/telecom/CallAudioRouteStateMachine.java
index cc5ee05..c803de5 100644
--- a/src/com/android/server/telecom/CallAudioRouteStateMachine.java
+++ b/src/com/android/server/telecom/CallAudioRouteStateMachine.java
@@ -840,6 +840,9 @@
             if (mFeatureFlags.callAudioCommunicationDeviceRefactor()) {
                 setBluetoothOn(null);
             }
+            if (mFeatureFlags.updateRouteMaskWhenBtConnected()) {
+                mAvailableRoutes |= ROUTE_BLUETOOTH;
+            }
             CallAudioState newState = new CallAudioState(mIsMuted, ROUTE_BLUETOOTH,
                     mAvailableRoutes, mBluetoothRouteManager.getBluetoothAudioConnectedDevice(),
                     mBluetoothRouteManager.getConnectedDevices());
diff --git a/tests/src/com/android/server/telecom/tests/CallAudioRouteStateMachineTest.java b/tests/src/com/android/server/telecom/tests/CallAudioRouteStateMachineTest.java
index 19dfe83..d95d875 100644
--- a/tests/src/com/android/server/telecom/tests/CallAudioRouteStateMachineTest.java
+++ b/tests/src/com/android/server/telecom/tests/CallAudioRouteStateMachineTest.java
@@ -1238,6 +1238,37 @@
         assertEquals(expectedState, stateMachine.getCurrentCallAudioState());
     }
 
+    @SmallTest
+    @Test
+    public void testSupportRouteMaskUpdateWhenBtAudioConnected() {
+        when(mFeatureFlags.updateRouteMaskWhenBtConnected()).thenReturn(true);
+        CallAudioRouteStateMachine stateMachine = new CallAudioRouteStateMachine(
+                mContext,
+                mockCallsManager,
+                mockBluetoothRouteManager,
+                mockWiredHeadsetManager,
+                mockStatusBarNotifier,
+                mAudioServiceFactory,
+                CallAudioRouteStateMachine.EARPIECE_FORCE_ENABLED,
+                mThreadHandler.getLooper(),
+                Runnable::run /** do async stuff sync for test purposes */,
+                mCommunicationDeviceTracker,
+                mFeatureFlags);
+        stateMachine.setCallAudioManager(mockCallAudioManager);
+
+        CallAudioState initState = new CallAudioState(false,
+                CallAudioState.ROUTE_EARPIECE,
+                CallAudioState.ROUTE_EARPIECE | CallAudioState.ROUTE_SPEAKER);
+        stateMachine.initialize(initState);
+
+        stateMachine.sendMessageWithSessionInfo(CallAudioRouteStateMachine.BT_AUDIO_CONNECTED);
+        waitForHandlerAction(stateMachine.getAdapterHandler(), TEST_TIMEOUT);
+        CallAudioState expectedState = new CallAudioState(false, CallAudioState.ROUTE_BLUETOOTH,
+                CallAudioState.ROUTE_EARPIECE | CallAudioState.ROUTE_SPEAKER
+                        | CallAudioState.ROUTE_BLUETOOTH);
+        assertEquals(expectedState, stateMachine.getCurrentCallAudioState());
+    }
+
     private void initializationTestHelper(CallAudioState expectedState,
             int earpieceControl) {
         when(mockWiredHeadsetManager.isPluggedIn()).thenReturn(