diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 04d0b93..60523dd 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -934,6 +934,15 @@
     private final Map<String, ApplicationSelfCertifiedNetworkCapabilities>
             mSelfCertifiedCapabilityCache = new HashMap<>();
 
+    // Flag to enable the feature of closing frozen app sockets.
+    private final boolean mDestroyFrozenSockets;
+
+    // Flag to optimize closing frozen app sockets by waiting for the cellular modem to wake up.
+    private final boolean mDelayDestroyFrozenSockets;
+
+    // Uids that ConnectivityService is pending to close sockets of.
+    private final Set<Integer> mPendingFrozenUids = new ArraySet<>();
+
     /**
      * Implements support for the legacy "one network per network type" model.
      *
@@ -1772,8 +1781,11 @@
             mCdmps = null;
         }
 
-        if (mDeps.isAtLeastU()
-                && mDeps.isFeatureEnabled(context, KEY_DESTROY_FROZEN_SOCKETS_VERSION)) {
+        mDestroyFrozenSockets = mDeps.isAtLeastU()
+                && mDeps.isFeatureEnabled(context, KEY_DESTROY_FROZEN_SOCKETS_VERSION);
+        mDelayDestroyFrozenSockets = mDeps.isAtLeastU()
+                && mDeps.isFeatureEnabled(context, DELAY_DESTROY_FROZEN_SOCKETS_VERSION);
+        if (mDestroyFrozenSockets) {
             final UidFrozenStateChangedCallback frozenStateChangedCallback =
                     new UidFrozenStateChangedCallback() {
                 @Override
@@ -2983,26 +2995,109 @@
         }
     }
 
+    /**
+     * Check if the cell network is idle.
+     * @return true if the cell network state is idle
+     *         false if the cell network state is active or unknown
+     */
+    private boolean isCellNetworkIdle() {
+        final NetworkAgentInfo defaultNai = getDefaultNetwork();
+        if (defaultNai == null
+                || !defaultNai.networkCapabilities.hasTransport(TRANSPORT_CELLULAR)) {
+            // mNetworkActivityTracker only tracks the activity of the default network. So if the
+            // cell network is not the default network, cell network state is unknown.
+            // TODO(b/279380356): Track cell network state when the cell is not the default network
+            return false;
+        }
+
+        return !mNetworkActivityTracker.isDefaultNetworkActive();
+    }
+
     private void handleFrozenUids(int[] uids, int[] frozenStates) {
         final ArraySet<Integer> ownerUids = new ArraySet<>();
 
         for (int i = 0; i < uids.length; i++) {
             if (frozenStates[i] == UID_FROZEN_STATE_FROZEN) {
                 ownerUids.add(uids[i]);
+            } else {
+                mPendingFrozenUids.remove(uids[i]);
             }
         }
 
-        if (!ownerUids.isEmpty()) {
+        if (ownerUids.isEmpty()) {
+            return;
+        }
+
+        if (mDelayDestroyFrozenSockets && isCellNetworkIdle()) {
+            // Delay closing sockets to avoid waking the cell modem up.
+            // Wi-Fi network state is not considered since waking Wi-Fi modem up is much cheaper
+            // than waking cell modem up.
+            mPendingFrozenUids.addAll(ownerUids);
+        } else {
             try {
                 mDeps.destroyLiveTcpSocketsByOwnerUids(ownerUids);
-            } catch (Exception e) {
+            } catch (SocketException | InterruptedIOException | ErrnoException e) {
                 loge("Exception in socket destroy: " + e);
             }
         }
     }
 
+    private void closePendingFrozenSockets() {
+        ensureRunningOnConnectivityServiceThread();
+
+        try {
+            mDeps.destroyLiveTcpSocketsByOwnerUids(mPendingFrozenUids);
+        } catch (SocketException | InterruptedIOException | ErrnoException e) {
+            loge("Failed to close pending frozen app sockets: " + e);
+        }
+        mPendingFrozenUids.clear();
+    }
+
+    private void handleReportNetworkActivity(final NetworkActivityParams params) {
+        mNetworkActivityTracker.handleReportNetworkActivity(params);
+
+        if (mDelayDestroyFrozenSockets
+                && params.isActive
+                && params.label == TRANSPORT_CELLULAR
+                && !mPendingFrozenUids.isEmpty()) {
+            closePendingFrozenSockets();
+        }
+    }
+
+    /**
+     * If the cellular network is no longer the default network, close pending frozen sockets.
+     *
+     * @param newNetwork new default network
+     * @param oldNetwork old default network
+     */
+    private void maybeClosePendingFrozenSockets(NetworkAgentInfo newNetwork,
+            NetworkAgentInfo oldNetwork) {
+        final boolean isOldNetworkCellular = oldNetwork != null
+                && oldNetwork.networkCapabilities.hasTransport(TRANSPORT_CELLULAR);
+        final boolean isNewNetworkCellular = newNetwork != null
+                && newNetwork.networkCapabilities.hasTransport(TRANSPORT_CELLULAR);
+
+        if (isOldNetworkCellular
+                && !isNewNetworkCellular
+                && !mPendingFrozenUids.isEmpty()) {
+            closePendingFrozenSockets();
+        }
+    }
+
+    private void dumpCloseFrozenAppSockets(IndentingPrintWriter pw) {
+        pw.println("CloseFrozenAppSockets:");
+        pw.increaseIndent();
+        pw.print("mDestroyFrozenSockets="); pw.println(mDestroyFrozenSockets);
+        pw.print("mDelayDestroyFrozenSockets="); pw.println(mDelayDestroyFrozenSockets);
+        pw.print("mPendingFrozenUids="); pw.println(mPendingFrozenUids);
+        pw.decreaseIndent();
+    }
+
     @VisibleForTesting
     static final String KEY_DESTROY_FROZEN_SOCKETS_VERSION = "destroy_frozen_sockets_version";
+    @VisibleForTesting
+    static final String DELAY_DESTROY_FROZEN_SOCKETS_VERSION =
+            "delay_destroy_frozen_sockets_version";
 
     private void enforceInternetPermission() {
         mContext.enforceCallingOrSelfPermission(
@@ -3605,6 +3700,9 @@
         dumpAvoidBadWifiSettings(pw);
 
         pw.println();
+        dumpCloseFrozenAppSockets(pw);
+
+        pw.println();
 
         if (!CollectionUtils.contains(args, SHORT_ARG)) {
             pw.println();
@@ -4671,6 +4769,7 @@
                     //  incorrect) behavior.
                     mNetworkActivityTracker.updateDataActivityTracking(
                             null /* newNetwork */, nai);
+                    maybeClosePendingFrozenSockets(null /* newNetwork */, nai);
                     ensureNetworkTransitionWakelock(nai.toShortString());
                 }
             }
@@ -5877,7 +5976,7 @@
                 }
                 case EVENT_REPORT_NETWORK_ACTIVITY:
                     final NetworkActivityParams arg = (NetworkActivityParams) msg.obj;
-                    mNetworkActivityTracker.handleReportNetworkActivity(arg);
+                    handleReportNetworkActivity(arg);
                     break;
                 case EVENT_MOBILE_DATA_PREFERRED_UIDS_CHANGED:
                     handleMobileDataPreferredUidsChanged();
@@ -9117,6 +9216,7 @@
             mLingerMonitor.noteLingerDefaultNetwork(oldDefaultNetwork, newDefaultNetwork);
         }
         mNetworkActivityTracker.updateDataActivityTracking(newDefaultNetwork, oldDefaultNetwork);
+        maybeClosePendingFrozenSockets(newDefaultNetwork, oldDefaultNetwork);
         mProxyTracker.setDefaultProxy(null != newDefaultNetwork
                 ? newDefaultNetwork.linkProperties.getHttpProxy() : null);
         resetHttpProxyForNonDefaultNetwork(oldDefaultNetwork);
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index f8e3166..e5dec56 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -154,6 +154,7 @@
 import static android.os.Process.INVALID_UID;
 import static android.system.OsConstants.IPPROTO_TCP;
 
+import static com.android.server.ConnectivityService.DELAY_DESTROY_FROZEN_SOCKETS_VERSION;
 import static com.android.server.ConnectivityService.KEY_DESTROY_FROZEN_SOCKETS_VERSION;
 import static com.android.server.ConnectivityService.MAX_NETWORK_REQUESTS_PER_SYSTEM_UID;
 import static com.android.server.ConnectivityService.PREFERENCE_ORDER_MOBILE_DATA_PREFERERRED;
@@ -214,6 +215,7 @@
 import static org.mockito.Matchers.anyInt;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.doReturn;
@@ -2130,6 +2132,8 @@
                     return true;
                 case KEY_DESTROY_FROZEN_SOCKETS_VERSION:
                     return true;
+                case DELAY_DESTROY_FROZEN_SOCKETS_VERSION:
+                    return true;
                 default:
                     return super.isFeatureEnabled(context, name);
             }
@@ -2280,7 +2284,9 @@
         @Override @SuppressWarnings("DirectInvocationOnMock")
         public void destroyLiveTcpSocketsByOwnerUids(final Set<Integer> ownerUids) {
             // Call mocked destroyLiveTcpSocketsByOwnerUids so that test can verify this method call
-            mDestroySocketsWrapper.destroyLiveTcpSocketsByOwnerUids(ownerUids);
+            // Create copy of ownerUids so that tests can verify the correct value even if the
+            // ConnectivityService update the ownerUids after this method call.
+            mDestroySocketsWrapper.destroyLiveTcpSocketsByOwnerUids(new ArraySet<>(ownerUids));
         }
 
         final ArrayTrackRecord<Pair<Integer, Long>>.ReadHead mScheduledEvaluationTimeouts =
@@ -11290,6 +11296,9 @@
     }
 
     private void doTestInterfaceClassActivityChanged(final int transportType) throws Exception {
+        final BaseNetdUnsolicitedEventListener netdUnsolicitedEventListener =
+                getRegisteredNetdUnsolicitedEventListener();
+
         final int legacyType = transportToLegacyType(transportType);
         final LinkProperties lp = new LinkProperties();
         lp.setInterfaceName(transportToTestIfaceName(transportType));
@@ -11306,12 +11315,8 @@
 
             mCm.addDefaultNetworkActiveListener(listener);
 
-            ArgumentCaptor<BaseNetdUnsolicitedEventListener> netdCallbackCaptor =
-                    ArgumentCaptor.forClass(BaseNetdUnsolicitedEventListener.class);
-            verify(mMockNetd).registerUnsolicitedEventListener(netdCallbackCaptor.capture());
-
             // Interface goes to inactive state
-            netdCallbackCaptor.getValue().onInterfaceClassActivityChanged(false /* isActive */,
+            netdUnsolicitedEventListener.onInterfaceClassActivityChanged(false /* isActive */,
                     transportType, TIMESTAMP, NETWORK_ACTIVITY_NO_UID);
             mServiceContext.expectDataActivityBroadcast(legacyType, false /* isActive */,
                     TIMESTAMP);
@@ -11319,7 +11324,7 @@
             assertFalse(mCm.isDefaultNetworkActive());
 
             // Interface goes to active state
-            netdCallbackCaptor.getValue().onInterfaceClassActivityChanged(true /* isActive */,
+            netdUnsolicitedEventListener.onInterfaceClassActivityChanged(true /* isActive */,
                     transportType, TIMESTAMP, TEST_PACKAGE_UID);
             mServiceContext.expectDataActivityBroadcast(legacyType, true /* isActive */, TIMESTAMP);
             assertTrue(onNetworkActiveCv.block(TEST_CALLBACK_TIMEOUT_MS));
@@ -18566,6 +18571,27 @@
                 anyInt());
     }
 
+    // UidFrozenStateChangedCallback is added in U API.
+    // Returning UidFrozenStateChangedCallback directly makes the test fail on T- devices since
+    // AndroidJUnit4ClassRunner iterates all declared methods and tries to resolve the return type.
+    // Solve this by wrapping it in an AtomicReference. Because of erasure, this removes the
+    // resolving problem as the type isn't seen dynamically.
+    private AtomicReference<UidFrozenStateChangedCallback> getUidFrozenStateChangedCallback() {
+        ArgumentCaptor<UidFrozenStateChangedCallback> activityManagerCallbackCaptor =
+                ArgumentCaptor.forClass(UidFrozenStateChangedCallback.class);
+        verify(mActivityManager).registerUidFrozenStateChangedCallback(any(),
+                activityManagerCallbackCaptor.capture());
+        return new AtomicReference<>(activityManagerCallbackCaptor.getValue());
+    }
+
+    private BaseNetdUnsolicitedEventListener getRegisteredNetdUnsolicitedEventListener()
+            throws RemoteException {
+        ArgumentCaptor<BaseNetdUnsolicitedEventListener> netdCallbackCaptor =
+                ArgumentCaptor.forClass(BaseNetdUnsolicitedEventListener.class);
+        verify(mMockNetd).registerUnsolicitedEventListener(netdCallbackCaptor.capture());
+        return netdCallbackCaptor.getValue();
+    }
+
     private static final int TEST_FROZEN_UID = 1000;
     private static final int TEST_UNFROZEN_UID = 2000;
 
@@ -18576,22 +18602,177 @@
     @Test
     @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
     public void testFrozenUidSocketDestroy() throws Exception {
-        ArgumentCaptor<UidFrozenStateChangedCallback> callbackArg =
-                ArgumentCaptor.forClass(UidFrozenStateChangedCallback.class);
-
-        verify(mActivityManager).registerUidFrozenStateChangedCallback(any(),
-                callbackArg.capture());
+        final UidFrozenStateChangedCallback callback =
+                getUidFrozenStateChangedCallback().get();
 
         final int[] uids = {TEST_FROZEN_UID, TEST_UNFROZEN_UID};
         final int[] frozenStates = {UID_FROZEN_STATE_FROZEN, UID_FROZEN_STATE_UNFROZEN};
 
-        callbackArg.getValue().onUidFrozenStateChanged(uids, frozenStates);
+        callback.onUidFrozenStateChanged(uids, frozenStates);
 
         waitForIdle();
 
         verify(mDestroySocketsWrapper).destroyLiveTcpSocketsByOwnerUids(Set.of(TEST_FROZEN_UID));
     }
 
+    private void doTestDelayFrozenUidSocketDestroy(int transportType,
+            boolean freezeWithNetworkInactive, boolean expectDelay) throws Exception {
+        final TestNetworkCallback defaultCallback = new TestNetworkCallback();
+        final LinkProperties lp = new LinkProperties();
+        lp.setInterfaceName(transportToTestIfaceName(transportType));
+        final TestNetworkAgentWrapper agent = new TestNetworkAgentWrapper(transportType, lp);
+        testAndCleanup(() -> {
+            final UidFrozenStateChangedCallback uidFrozenStateChangedCallback =
+                    getUidFrozenStateChangedCallback().get();
+            final BaseNetdUnsolicitedEventListener netdUnsolicitedEventListener =
+                    getRegisteredNetdUnsolicitedEventListener();
+
+            mCm.registerDefaultNetworkCallback(defaultCallback);
+            agent.connect(true);
+            defaultCallback.expectAvailableThenValidatedCallbacks(agent);
+            if (freezeWithNetworkInactive) {
+                // Make network inactive
+                netdUnsolicitedEventListener.onInterfaceClassActivityChanged(false /* isActive */,
+                        transportType, TIMESTAMP, NETWORK_ACTIVITY_NO_UID);
+            }
+
+            // Freeze TEST_FROZEN_UID and TEST_UNFROZEN_UID
+            final int[] uids1 = {TEST_FROZEN_UID, TEST_UNFROZEN_UID};
+            final int[] frozenStates1 = {UID_FROZEN_STATE_FROZEN, UID_FROZEN_STATE_FROZEN};
+            uidFrozenStateChangedCallback.onUidFrozenStateChanged(uids1, frozenStates1);
+            waitForIdle();
+
+            if (expectDelay) {
+                verify(mDestroySocketsWrapper, never()).destroyLiveTcpSocketsByOwnerUids(any());
+            } else {
+                verify(mDestroySocketsWrapper).destroyLiveTcpSocketsByOwnerUids(
+                        Set.of(TEST_FROZEN_UID, TEST_UNFROZEN_UID));
+                clearInvocations(mDestroySocketsWrapper);
+            }
+
+            // Unfreeze TEST_UNFROZEN_UID
+            final int[] uids2 = {TEST_UNFROZEN_UID};
+            final int[] frozenStates2 = {UID_FROZEN_STATE_UNFROZEN};
+            uidFrozenStateChangedCallback.onUidFrozenStateChanged(uids2, frozenStates2);
+
+            // Make network active
+            netdUnsolicitedEventListener.onInterfaceClassActivityChanged(true /* isActive */,
+                    transportType, TIMESTAMP, TEST_PACKAGE_UID);
+            waitForIdle();
+
+            if (expectDelay) {
+                verify(mDestroySocketsWrapper).destroyLiveTcpSocketsByOwnerUids(
+                        Set.of(TEST_FROZEN_UID));
+            } else {
+                verify(mDestroySocketsWrapper, never()).destroyLiveTcpSocketsByOwnerUids(any());
+            }
+        }, () -> { // Cleanup
+                agent.disconnect();
+            }, () -> {
+                mCm.unregisterNetworkCallback(defaultCallback);
+            });
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testDelayFrozenUidSocketDestroy_ActiveCellular() throws Exception {
+        doTestDelayFrozenUidSocketDestroy(TRANSPORT_CELLULAR,
+                false /* freezeWithNetworkInactive */, false /* expectDelay */);
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testDelayFrozenUidSocketDestroy_InactiveCellular() throws Exception {
+        // When the default network is cellular and cellular network is inactive, closing socket
+        // is delayed.
+        doTestDelayFrozenUidSocketDestroy(TRANSPORT_CELLULAR,
+                true /* freezeWithNetworkInactive */, true /* expectDelay */);
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testDelayFrozenUidSocketDestroy_ActiveWifi() throws Exception {
+        doTestDelayFrozenUidSocketDestroy(TRANSPORT_WIFI,
+                false /* freezeWithNetworkInactive */, false /* expectDelay */);
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testDelayFrozenUidSocketDestroy_InactiveWifi() throws Exception {
+        doTestDelayFrozenUidSocketDestroy(TRANSPORT_WIFI,
+                true /* freezeWithNetworkInactive */, false /* expectDelay */);
+    }
+
+    /**
+     * @param switchToWifi if true, simulate a migration of the default network to wifi
+     *                     if false, simulate a cell disconnection
+     */
+    private void doTestLoseCellDefaultNetwork_ClosePendingFrozenSockets(final boolean switchToWifi)
+            throws Exception {
+        final UidFrozenStateChangedCallback uidFrozenStateChangedCallback =
+                getUidFrozenStateChangedCallback().get();
+        final BaseNetdUnsolicitedEventListener netdUnsolicitedEventListener =
+                getRegisteredNetdUnsolicitedEventListener();
+
+        final LinkProperties wifiLp = new LinkProperties();
+        wifiLp.setInterfaceName(WIFI_IFNAME);
+        mWiFiAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI, wifiLp);
+
+        final LinkProperties cellLp = new LinkProperties();
+        cellLp.setInterfaceName(MOBILE_IFNAME);
+        mCellAgent = new TestNetworkAgentWrapper(TRANSPORT_CELLULAR, cellLp);
+
+        final TestNetworkCallback defaultCallback = new TestNetworkCallback();
+        mCm.registerDefaultNetworkCallback(defaultCallback);
+        try {
+            mCellAgent.connect(true);
+            defaultCallback.expectAvailableThenValidatedCallbacks(mCellAgent);
+
+            // Make cell network inactive
+            netdUnsolicitedEventListener.onInterfaceClassActivityChanged(false /* isActive */,
+                    TRANSPORT_CELLULAR, TIMESTAMP, NETWORK_ACTIVITY_NO_UID);
+
+            // Freeze TEST_FROZEN_UID
+            final int[] uids = {TEST_FROZEN_UID};
+            final int[] frozenStates = {UID_FROZEN_STATE_FROZEN};
+            uidFrozenStateChangedCallback.onUidFrozenStateChanged(uids, frozenStates);
+            waitForIdle();
+
+            // Closing frozen sockets should be delayed since the default network is cellular
+            // and cellular network is inactive.
+            verify(mDestroySocketsWrapper, never()).destroyLiveTcpSocketsByOwnerUids(any());
+
+            if (switchToWifi) {
+                mWiFiAgent.connect(true);
+                defaultCallback.expectAvailableDoubleValidatedCallbacks(mWiFiAgent);
+            } else {
+                mCellAgent.disconnect();
+                waitForIdle();
+            }
+
+            // Pending frozen sockets should be closed since the cellular network is no longer the
+            // default network.
+            verify(mDestroySocketsWrapper)
+                    .destroyLiveTcpSocketsByOwnerUids(Set.of(TEST_FROZEN_UID));
+        } finally {
+            mCm.unregisterNetworkCallback(defaultCallback);
+        }
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testLoseCellDefaultNetwork_SwitchToWifi_ClosePendingFrozenSockets()
+            throws Exception {
+        doTestLoseCellDefaultNetwork_ClosePendingFrozenSockets(true /* switchToWifi */);
+    }
+
+    @Test
+    @IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+    public void testLoseCellDefaultNetwork_NoDefaultNetwork_ClosePendingFrozenSockets()
+            throws Exception {
+        doTestLoseCellDefaultNetwork_ClosePendingFrozenSockets(false /* switchToWifi */);
+    }
+
     @Test
     public void testDisconnectSuspendedNetworkStopClatd() throws Exception {
         final TestNetworkCallback networkCallback = new TestNetworkCallback();