diff --git a/service/src/com/android/server/connectivity/KeepaliveStatsTracker.java b/service/src/com/android/server/connectivity/KeepaliveStatsTracker.java
index f9213d7..d59d526 100644
--- a/service/src/com/android/server/connectivity/KeepaliveStatsTracker.java
+++ b/service/src/com/android/server/connectivity/KeepaliveStatsTracker.java
@@ -19,7 +19,10 @@
 import static android.telephony.SubscriptionManager.OnSubscriptionsChangedListener;
 
 import android.annotation.NonNull;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.net.NetworkSpecifier;
@@ -69,9 +72,7 @@
     // Mapping of subId to carrierId. Updates are received from OnSubscriptionsChangedListener
     private final SparseIntArray mCachedCarrierIdPerSubId = new SparseIntArray();
     // The default subscription id obtained from SubscriptionManager.getDefaultSubscriptionId.
-    // Updates are done from the OnSubscriptionsChangedListener. Note that there is no callback done
-    // to OnSubscriptionsChangedListener when the default sub id changes.
-    // TODO: Register a listener for the default subId when it is possible.
+    // Updates are received from the ACTION_DEFAULT_SUBSCRIPTION_CHANGED broadcast.
     private int mCachedDefaultSubscriptionId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
     // Class to store network information, lifetime durations and active state of a keepalive.
@@ -269,6 +270,19 @@
                 Objects.requireNonNull(context.getSystemService(SubscriptionManager.class));
 
         mLastUpdateDurationsTimestamp = mDependencies.getElapsedRealtime();
+        context.registerReceiver(
+                new BroadcastReceiver() {
+                    @Override
+                    public void onReceive(Context context, Intent intent) {
+                        mCachedDefaultSubscriptionId =
+                                intent.getIntExtra(
+                                        SubscriptionManager.EXTRA_SUBSCRIPTION_INDEX,
+                                        SubscriptionManager.INVALID_SUBSCRIPTION_ID);
+                    }
+                },
+                new IntentFilter(SubscriptionManager.ACTION_DEFAULT_SUBSCRIPTION_CHANGED),
+                /* broadcastPermission= */ null,
+                mConnectivityServiceHandler);
 
         // The default constructor for OnSubscriptionsChangedListener will always implicitly grab
         // the looper of the current thread. In the case the current thread does not have a looper,
@@ -286,11 +300,8 @@
                                 // but not necessarily empty, simply ignore it. Another call to the
                                 // listener will be invoked in the future.
                                 if (activeSubInfoList == null) return;
-                                final int defaultSubId =
-                                        subscriptionManager.getDefaultSubscriptionId();
                                 mConnectivityServiceHandler.post(() -> {
                                     mCachedCarrierIdPerSubId.clear();
-                                    mCachedDefaultSubscriptionId = defaultSubId;
 
                                     for (final SubscriptionInfo subInfo : activeSubInfoList) {
                                         mCachedCarrierIdPerSubId.put(subInfo.getSubscriptionId(),
diff --git a/tests/unit/java/com/android/server/connectivity/KeepaliveStatsTrackerTest.java b/tests/unit/java/com/android/server/connectivity/KeepaliveStatsTrackerTest.java
index 9472ded..0d2e540 100644
--- a/tests/unit/java/com/android/server/connectivity/KeepaliveStatsTrackerTest.java
+++ b/tests/unit/java/com/android/server/connectivity/KeepaliveStatsTrackerTest.java
@@ -27,12 +27,15 @@
 import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doCallRealMethod;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
 import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.net.TelephonyNetworkSpecifier;
@@ -109,6 +112,18 @@
     @Mock private KeepaliveStatsTracker.Dependencies mDependencies;
     @Mock private SubscriptionManager mSubscriptionManager;
 
+    private void triggerBroadcastDefaultSubId(int subId) {
+        final ArgumentCaptor<BroadcastReceiver> receiverCaptor =
+                ArgumentCaptor.forClass(BroadcastReceiver.class);
+        verify(mContext).registerReceiver(receiverCaptor.capture(), /* filter= */ any(),
+                /* broadcastPermission= */ any(), eq(mTestHandler));
+        final Intent intent =
+                new Intent(TelephonyManager.ACTION_SUBSCRIPTION_CARRIER_IDENTITY_CHANGED);
+        intent.putExtra(SubscriptionManager.EXTRA_SUBSCRIPTION_INDEX, subId);
+
+        receiverCaptor.getValue().onReceive(mContext, intent);
+    }
+
     private OnSubscriptionsChangedListener getOnSubscriptionsChangedListener() {
         final ArgumentCaptor<OnSubscriptionsChangedListener> listenerCaptor =
                 ArgumentCaptor.forClass(OnSubscriptionsChangedListener.class);
@@ -1128,4 +1143,53 @@
                             writeTime * 3 - startTime1 - startTime2 - startTime3)
                 });
     }
+
+    @Test
+    public void testUpdateDefaultSubId() {
+        final int startTime1 = 1000;
+        final int startTime2 = 3000;
+        final int writeTime = 5000;
+
+        // No TelephonyNetworkSpecifier set with subId to force the use of default subId.
+        final NetworkCapabilities nc =
+                new NetworkCapabilities.Builder().addTransportType(TRANSPORT_CELLULAR).build();
+        onStartKeepalive(startTime1, TEST_SLOT, nc);
+        // Update default subId
+        triggerBroadcastDefaultSubId(TEST_SUB_ID_1);
+        onStartKeepalive(startTime2, TEST_SLOT2, nc);
+
+        final DailykeepaliveInfoReported dailyKeepaliveInfoReported =
+                buildKeepaliveMetrics(writeTime);
+
+        final int[] expectRegisteredDurations =
+                new int[] {startTime1, startTime2 - startTime1, writeTime - startTime2};
+        final int[] expectActiveDurations =
+                new int[] {startTime1, startTime2 - startTime1, writeTime - startTime2};
+        // Expect the carrier id of the first keepalive to be unknown
+        final KeepaliveCarrierStats expectKeepaliveCarrierStats1 =
+                new KeepaliveCarrierStats(
+                        TelephonyManager.UNKNOWN_CARRIER_ID,
+                        /* transportTypes= */ (1 << TRANSPORT_CELLULAR),
+                        TEST_KEEPALIVE_INTERVAL_SEC * 1000,
+                        writeTime - startTime1,
+                        writeTime - startTime1);
+        // Expect the carrier id of the second keepalive to be TEST_CARRIER_ID_1, from TEST_SUB_ID_1
+        final KeepaliveCarrierStats expectKeepaliveCarrierStats2 =
+                new KeepaliveCarrierStats(
+                        TEST_CARRIER_ID_1,
+                        /* transportTypes= */ (1 << TRANSPORT_CELLULAR),
+                        TEST_KEEPALIVE_INTERVAL_SEC * 1000,
+                        writeTime - startTime2,
+                        writeTime - startTime2);
+        assertDailyKeepaliveInfoReported(
+                dailyKeepaliveInfoReported,
+                /* expectRequestsCount= */ 2,
+                /* expectAutoRequestsCount= */ 2,
+                /* expectAppUids= */ new int[] {TEST_UID},
+                expectRegisteredDurations,
+                expectActiveDurations,
+                new KeepaliveCarrierStats[] {
+                    expectKeepaliveCarrierStats1, expectKeepaliveCarrierStats2
+                });
+    }
 }