diff --git a/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
index 4ca36df..844efde 100644
--- a/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
+++ b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
@@ -16,6 +16,7 @@
 
 package com.android.networkstack.tethering;
 
+import static android.content.pm.PackageManager.GET_ACTIVITIES;
 import static android.net.TetheringConstants.EXTRA_ADD_TETHER_TYPE;
 import static android.net.TetheringConstants.EXTRA_PROVISION_CALLBACK;
 import static android.net.TetheringConstants.EXTRA_RUN_PROVISION;
@@ -32,6 +33,9 @@
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_PROVISIONING_FAILED;
 
+import static com.android.networkstack.apishim.ConstantsShim.ACTION_TETHER_UNSUPPORTED_CARRIER_UI;
+import static com.android.networkstack.apishim.ConstantsShim.KEY_CARRIER_SUPPORTS_TETHERING_BOOL;
+
 import android.app.AlarmManager;
 import android.app.PendingIntent;
 import android.content.BroadcastReceiver;
@@ -39,6 +43,7 @@
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.content.pm.PackageManager;
 import android.net.util.SharedLog;
 import android.os.Bundle;
 import android.os.Handler;
@@ -52,6 +57,7 @@
 import android.util.SparseIntArray;
 
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.modules.utils.build.SdkLevel;
 
 import java.io.PrintWriter;
 import java.util.BitSet;
@@ -74,6 +80,13 @@
     protected static final String ACTION_PROVISIONING_ALARM =
             "com.android.networkstack.tethering.PROVISIONING_RECHECK_ALARM";
 
+    // Indicate tether provisioning is not required by carrier.
+    private static final int TETHERING_PROVISIONING_REQUIRED = 1000;
+    // Indicate tether provisioning is required by carrier.
+    private static final int TETHERING_PROVISIONING_NOT_REQUIRED = 1001;
+    // Indicate tethering is not supported by carrier.
+    private static final int TETHERING_PROVISIONING_CARRIER_UNSUPPORT = 1002;
+
     private final ComponentName mSilentProvisioningService;
     private static final int MS_PER_HOUR = 60 * 60 * 1000;
     private static final int DUMP_TIMEOUT = 10_000;
@@ -96,7 +109,7 @@
     private boolean mLastCellularUpstreamPermitted = true;
     private boolean mUsingCellularAsUpstream = false;
     private boolean mNeedReRunProvisioningUi = false;
-    private OnUiEntitlementFailedListener mListener;
+    private OnTetherProvisioningFailedListener mListener;
     private TetheringConfigurationFetcher mFetcher;
 
     public EntitlementManager(Context ctx, Handler h, SharedLog log,
@@ -115,18 +128,20 @@
                 mContext.getResources().getString(R.string.config_wifi_tether_enable));
     }
 
-    public void setOnUiEntitlementFailedListener(final OnUiEntitlementFailedListener listener) {
+    public void setOnTetherProvisioningFailedListener(
+            final OnTetherProvisioningFailedListener listener) {
         mListener = listener;
     }
 
     /** Callback fired when UI entitlement failed. */
-    public interface OnUiEntitlementFailedListener {
+    public interface OnTetherProvisioningFailedListener {
         /**
          * Ui entitlement check fails in |downstream|.
          *
          * @param downstream tethering type from TetheringManager.TETHERING_{@code *}.
+         * @param reason Failed reason.
          */
-        void onUiEntitlementFailed(int downstream);
+        void onTetherProvisioningFailed(int downstream, String reason);
     }
 
     public void setTetheringConfigurationFetcher(final TetheringConfigurationFetcher fetcher) {
@@ -153,6 +168,9 @@
     }
 
     private boolean isCellularUpstreamPermitted(final TetheringConfiguration config) {
+        // If #getTetherProvisioningCondition return TETHERING_PROVISIONING_CARRIER_UNSUPPORT,
+        // that means cellular upstream is not supported and entitlement check result is empty
+        // because entitlement check should not be run.
         if (!isTetherProvisioningRequired(config)) return true;
 
         // If provisioning is required and EntitlementManager doesn't know any downstreams, cellular
@@ -199,11 +217,7 @@
         // If upstream is not cellular, provisioning app would not be launched
         // till upstream change to cellular.
         if (mUsingCellularAsUpstream) {
-            if (showProvisioningUi) {
-                runUiTetherProvisioning(downstreamType, config);
-            } else {
-                runSilentTetherProvisioning(downstreamType, config);
-            }
+            runTetheringProvisioning(showProvisioningUi, downstreamType, config);
             mNeedReRunProvisioningUi = false;
         } else {
             mNeedReRunProvisioningUi |= showProvisioningUi;
@@ -262,18 +276,51 @@
         // the change and get the new correct value.
         for (int downstream = mCurrentDownstreams.nextSetBit(0); downstream >= 0;
                 downstream = mCurrentDownstreams.nextSetBit(downstream + 1)) {
+            // If tethering provisioning is required but entitlement check result is empty,
+            // this means tethering may need to run entitlement check or carrier network
+            // is not supported.
             if (mCurrentEntitlementResults.indexOfKey(downstream) < 0) {
-                if (mNeedReRunProvisioningUi) {
-                    mNeedReRunProvisioningUi = false;
-                    runUiTetherProvisioning(downstream, config);
-                } else {
-                    runSilentTetherProvisioning(downstream, config);
-                }
+                runTetheringProvisioning(mNeedReRunProvisioningUi, downstream, config);
+                mNeedReRunProvisioningUi = false;
             }
         }
     }
 
     /**
+     * Tether provisioning has these conditions to control provisioning behavior.
+     *  1st priority : Uses system property to disable any provisioning behavior.
+     *  2nd priority : Uses {@code CarrierConfigManager#KEY_CARRIER_SUPPORTS_TETHERING_BOOL} to
+     *                 decide current carrier support cellular upstream tethering or not.
+     *                 If value is true, it means check follow up condition to know whether
+     *                 provisioning is required.
+     *                 If value is false, it means tethering could not use cellular as upstream.
+     *  3rd priority : Uses {@code CarrierConfigManager#KEY_REQUIRE_ENTITLEMENT_CHECKS_BOOL} to
+     *                 decide current carrier require the provisioning.
+     *  4th priority : Checks whether provisioning is required from RRO configuration.
+     *
+     * @param config
+     * @return integer {@see #TETHERING_PROVISIONING_NOT_REQUIRED,
+     *                 #TETHERING_PROVISIONING_REQUIRED,
+     *                 #TETHERING_PROVISIONING_CARRIER_UNSUPPORT}
+     */
+    private int getTetherProvisioningCondition(final TetheringConfiguration config) {
+        if (SystemProperties.getBoolean(DISABLE_PROVISIONING_SYSPROP_KEY, false)) {
+            return TETHERING_PROVISIONING_NOT_REQUIRED;
+        }
+        // TODO: Find a way to avoid get carrier config twice.
+        if (carrierConfigAffirmsCarrierNotSupport(config)) {
+            // To block tethering, behave as if running provisioning check and failed.
+            return TETHERING_PROVISIONING_CARRIER_UNSUPPORT;
+        }
+
+        if (carrierConfigAffirmsEntitlementCheckNotRequired(config)) {
+            return TETHERING_PROVISIONING_NOT_REQUIRED;
+        }
+        return (config.provisioningApp.length == 2)
+                ? TETHERING_PROVISIONING_REQUIRED : TETHERING_PROVISIONING_NOT_REQUIRED;
+    }
+
+    /**
      * Check if the device requires a provisioning check in order to enable tethering.
      *
      * @param config an object that encapsulates the various tethering configuration elements.
@@ -281,14 +328,26 @@
      */
     @VisibleForTesting
     protected boolean isTetherProvisioningRequired(final TetheringConfiguration config) {
-        if (SystemProperties.getBoolean(DISABLE_PROVISIONING_SYSPROP_KEY, false)
-                || config.provisioningApp.length == 0) {
+        return getTetherProvisioningCondition(config) != TETHERING_PROVISIONING_NOT_REQUIRED;
+    }
+
+    /**
+     * Confirms the need of tethering provisioning but no entitlement package exists.
+     */
+    public boolean isProvisioningNeededButUnavailable() {
+        final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
+        return getTetherProvisioningCondition(config) == TETHERING_PROVISIONING_REQUIRED
+                && !doesEntitlementPackageExist(config);
+    }
+
+    private boolean doesEntitlementPackageExist(final TetheringConfiguration config) {
+        final PackageManager pm = mContext.getPackageManager();
+        try {
+            pm.getPackageInfo(config.provisioningApp[0], GET_ACTIVITIES);
+        } catch (PackageManager.NameNotFoundException e) {
             return false;
         }
-        if (carrierConfigAffirmsEntitlementCheckNotRequired(config)) {
-            return false;
-        }
-        return (config.provisioningApp.length == 2);
+        return true;
     }
 
     /**
@@ -310,9 +369,7 @@
         mEntitlementCacheValue.clear();
         mCurrentEntitlementResults.clear();
 
-        // TODO: refine provisioning check to isTetherProvisioningRequired() ??
-        if (!config.hasMobileHotspotProvisionApp()
-                || carrierConfigAffirmsEntitlementCheckNotRequired(config)) {
+        if (!isTetherProvisioningRequired(config)) {
             evaluateCellularPermission(config);
             return;
         }
@@ -327,8 +384,8 @@
      * @param config an object that encapsulates the various tethering configuration elements.
      * */
     public PersistableBundle getCarrierConfig(final TetheringConfiguration config) {
-        final CarrierConfigManager configManager = (CarrierConfigManager) mContext
-                .getSystemService(Context.CARRIER_CONFIG_SERVICE);
+        final CarrierConfigManager configManager = mContext
+                .getSystemService(CarrierConfigManager.class);
         if (configManager == null) return null;
 
         final PersistableBundle carrierConfig = configManager.getConfigForSubId(
@@ -346,6 +403,7 @@
     //
     // TODO: find a better way to express this, or alter the checking process
     // entirely so that this is more intuitive.
+    // TODO: Find a way to avoid using getCarrierConfig everytime.
     private boolean carrierConfigAffirmsEntitlementCheckNotRequired(
             final TetheringConfiguration config) {
         // Check carrier config for entitlement checks
@@ -358,16 +416,29 @@
         return !isEntitlementCheckRequired;
     }
 
+    private boolean carrierConfigAffirmsCarrierNotSupport(final TetheringConfiguration config) {
+        if (!SdkLevel.isAtLeastT()) {
+            return false;
+        }
+        // Check carrier config for entitlement checks
+        final PersistableBundle carrierConfig = getCarrierConfig(config);
+        if (carrierConfig == null) return false;
+
+        // A CarrierConfigManager was found and it has a config.
+        final boolean mIsCarrierSupport = carrierConfig.getBoolean(
+                KEY_CARRIER_SUPPORTS_TETHERING_BOOL, true);
+        return !mIsCarrierSupport;
+    }
+
     /**
      * Run no UI tethering provisioning check.
      * @param type tethering type from TetheringManager.TETHERING_{@code *}
      * @param subId default data subscription ID.
      */
     @VisibleForTesting
-    protected Intent runSilentTetherProvisioning(int type, final TetheringConfiguration config) {
+    protected Intent runSilentTetherProvisioning(
+            int type, final TetheringConfiguration config, ResultReceiver receiver) {
         if (DBG) mLog.i("runSilentTetherProvisioning: " + type);
-        // For silent provisioning, settings would stop tethering when entitlement fail.
-        ResultReceiver receiver = buildProxyReceiver(type, false/* notifyFail */, null);
 
         Intent intent = new Intent();
         intent.putExtra(EXTRA_ADD_TETHER_TYPE, type);
@@ -383,11 +454,6 @@
         return intent;
     }
 
-    private void runUiTetherProvisioning(int type, final TetheringConfiguration config) {
-        ResultReceiver receiver = buildProxyReceiver(type, true/* notifyFail */, null);
-        runUiTetherProvisioning(type, config, receiver);
-    }
-
     /**
      * Run the UI-enabled tethering provisioning check.
      * @param type tethering type from TetheringManager.TETHERING_{@code *}
@@ -411,6 +477,35 @@
         return intent;
     }
 
+    private void runTetheringProvisioning(
+            boolean showProvisioningUi, int downstreamType, final TetheringConfiguration config) {
+        if (carrierConfigAffirmsCarrierNotSupport(config)) {
+            mListener.onTetherProvisioningFailed(downstreamType, "Carrier does not support.");
+            if (showProvisioningUi) {
+                showCarrierUnsupportedDialog();
+            }
+            return;
+        }
+
+        ResultReceiver receiver =
+                buildProxyReceiver(downstreamType, showProvisioningUi/* notifyFail */, null);
+        if (showProvisioningUi) {
+            runUiTetherProvisioning(downstreamType, config, receiver);
+        } else {
+            runSilentTetherProvisioning(downstreamType, config, receiver);
+        }
+    }
+
+    private void showCarrierUnsupportedDialog() {
+        // This is only used when carrierConfigAffirmsCarrierNotSupport() is true.
+        if (!SdkLevel.isAtLeastT()) {
+            return;
+        }
+        Intent intent = new Intent(ACTION_TETHER_UNSUPPORTED_CARRIER_UI);
+        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        mContext.startActivity(intent);
+    }
+
     @VisibleForTesting
     PendingIntent createRecheckAlarmIntent() {
         final Intent intent = new Intent(ACTION_PROVISIONING_ALARM);
@@ -576,7 +671,8 @@
                 int updatedCacheValue = updateEntitlementCacheValue(type, resultCode);
                 addDownstreamMapping(type, updatedCacheValue);
                 if (updatedCacheValue == TETHER_ERROR_PROVISIONING_FAILED && notifyFail) {
-                    mListener.onUiEntitlementFailed(type);
+                    mListener.onTetherProvisioningFailed(
+                            type, "Tethering provisioning failed.");
                 }
                 if (receiver != null) receiver.send(updatedCacheValue, null);
             }
@@ -632,9 +728,14 @@
         }
 
         final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
-        if (!isTetherProvisioningRequired(config)) {
-            receiver.send(TETHER_ERROR_NO_ERROR, null);
-            return;
+
+        switch (getTetherProvisioningCondition(config)) {
+            case TETHERING_PROVISIONING_NOT_REQUIRED:
+                receiver.send(TETHER_ERROR_NO_ERROR, null);
+                return;
+            case TETHERING_PROVISIONING_CARRIER_UNSUPPORT:
+                receiver.send(TETHER_ERROR_PROVISIONING_FAILED, null);
+                return;
         }
 
         final int cacheValue = mEntitlementCacheValue.get(
diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index bb9b6fb..0b607bd 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -18,7 +18,6 @@
 
 import static android.Manifest.permission.NETWORK_SETTINGS;
 import static android.Manifest.permission.NETWORK_STACK;
-import static android.content.pm.PackageManager.GET_ACTIVITIES;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.hardware.usb.UsbManager.USB_CONFIGURED;
 import static android.hardware.usb.UsbManager.USB_CONNECTED;
@@ -319,8 +318,8 @@
         mEntitlementMgr = mDeps.getEntitlementManager(mContext, mHandler, mLog,
                 () -> mTetherMainSM.sendMessage(
                 TetherMainSM.EVENT_UPSTREAM_PERMISSION_CHANGED));
-        mEntitlementMgr.setOnUiEntitlementFailedListener((int downstream) -> {
-            mLog.log("OBSERVED UiEnitlementFailed");
+        mEntitlementMgr.setOnTetherProvisioningFailedListener((downstream, reason) -> {
+            mLog.log("OBSERVED OnTetherProvisioningFailed : " + reason);
             stopTethering(downstream);
         });
         mEntitlementMgr.setTetheringConfigurationFetcher(() -> {
@@ -995,30 +994,11 @@
         return tetherState.lastError;
     }
 
-    private boolean isProvisioningNeededButUnavailable() {
-        return isTetherProvisioningRequired() && !doesEntitlementPackageExist();
-    }
-
     boolean isTetherProvisioningRequired() {
         final TetheringConfiguration cfg = mConfig;
         return mEntitlementMgr.isTetherProvisioningRequired(cfg);
     }
 
-    private boolean doesEntitlementPackageExist() {
-        // provisioningApp must contain package and class name.
-        if (mConfig.provisioningApp.length != 2) {
-            return false;
-        }
-
-        final PackageManager pm = mContext.getPackageManager();
-        try {
-            pm.getPackageInfo(mConfig.provisioningApp[0], GET_ACTIVITIES);
-        } catch (PackageManager.NameNotFoundException e) {
-            return false;
-        }
-        return true;
-    }
-
     private int getRequestedState(int type) {
         final TetheringRequestParcel request = mActiveTetheringRequests.get(type);
 
@@ -2476,7 +2456,7 @@
                 && !mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_TETHERING);
 
         return tetherEnabledInSettings && hasAnySupportedDownstream()
-                && !isProvisioningNeededButUnavailable();
+                && !mEntitlementMgr.isProvisioningNeededButUnavailable();
     }
 
     private void dumpBpf(IndentingPrintWriter pw) {
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
index 46ce82c..690ff71 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
@@ -37,6 +37,9 @@
 
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.doReturn;
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.mockitoSession;
+import static com.android.networkstack.apishim.ConstantsShim.KEY_CARRIER_SUPPORTS_TETHERING_BOOL;
+import static com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
+import static com.android.testutils.DevSdkIgnoreRuleKt.SC_V2;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -47,6 +50,7 @@
 import static org.mockito.Matchers.anyString;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
@@ -77,9 +81,12 @@
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.internal.util.test.BroadcastInterceptingContext;
+import com.android.modules.utils.build.SdkLevel;
+import com.android.testutils.DevSdkIgnoreRule;
 
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.InOrder;
@@ -96,6 +103,7 @@
     private static final String PROVISIONING_NO_UI_APP_NAME = "no_ui_app";
     private static final String PROVISIONING_APP_RESPONSE = "app_response";
     private static final String TEST_PACKAGE_NAME = "com.android.tethering.test";
+    private static final String FAILED_TETHERING_REASON = "Tethering provisioning failed.";
     private static final int RECHECK_TIMER_HOURS = 24;
 
     @Mock private CarrierConfigManager mCarrierConfigManager;
@@ -103,10 +111,14 @@
     @Mock private Resources mResources;
     @Mock private SharedLog mLog;
     @Mock private PackageManager mPm;
-    @Mock private EntitlementManager.OnUiEntitlementFailedListener mEntitlementFailedListener;
+    @Mock private EntitlementManager
+            .OnTetherProvisioningFailedListener mTetherProvisioningFailedListener;
     @Mock private AlarmManager mAlarmManager;
     @Mock private PendingIntent mAlarmIntent;
 
+    @Rule
+    public final DevSdkIgnoreRule ignoreRule = new DevSdkIgnoreRule();
+
     // Like so many Android system APIs, these cannot be mocked because it is marked final.
     // We have to use the real versions.
     private final PersistableBundle mCarrierConfig = new PersistableBundle();
@@ -179,8 +191,8 @@
 
         @Override
         protected Intent runSilentTetherProvisioning(int type,
-                final TetheringConfiguration config) {
-            Intent intent = super.runSilentTetherProvisioning(type, config);
+                final TetheringConfiguration config, final ResultReceiver receiver) {
+            Intent intent = super.runSilentTetherProvisioning(type, config, receiver);
             assertSilentTetherProvisioning(type, config, intent);
             silentProvisionCount++;
             addDownstreamMapping(type, fakeEntitlementResult);
@@ -245,7 +257,7 @@
         mPermissionChangeCallback = spy(() -> { });
         mEnMgr = new WrappedEntitlementManager(mMockContext, new Handler(mLooper.getLooper()), mLog,
                 mPermissionChangeCallback);
-        mEnMgr.setOnUiEntitlementFailedListener(mEntitlementFailedListener);
+        mEnMgr.setOnTetherProvisioningFailedListener(mTetherProvisioningFailedListener);
         mConfig = new FakeTetheringConfiguration(mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
         mEnMgr.setTetheringConfigurationFetcher(() -> {
             return mConfig;
@@ -268,14 +280,23 @@
         when(mResources.getInteger(R.integer.config_mobile_hotspot_provision_check_period))
                 .thenReturn(RECHECK_TIMER_HOURS);
         // Act like the CarrierConfigManager is present and ready unless told otherwise.
-        when(mContext.getSystemService(Context.CARRIER_CONFIG_SERVICE))
-                .thenReturn(mCarrierConfigManager);
+        mockService(Context.CARRIER_CONFIG_SERVICE,
+                CarrierConfigManager.class, mCarrierConfigManager);
         when(mCarrierConfigManager.getConfigForSubId(anyInt())).thenReturn(mCarrierConfig);
         mCarrierConfig.putBoolean(CarrierConfigManager.KEY_REQUIRE_ENTITLEMENT_CHECKS_BOOL, true);
         mCarrierConfig.putBoolean(CarrierConfigManager.KEY_CARRIER_CONFIG_APPLIED_BOOL, true);
         mConfig = new FakeTetheringConfiguration(mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
     }
 
+    private void setupCarrierConfig(boolean carrierSupported) {
+        mCarrierConfig.putBoolean(KEY_CARRIER_SUPPORTS_TETHERING_BOOL, carrierSupported);
+    }
+
+    private <T> void mockService(String serviceName, Class<T> serviceClass, T service) {
+        when(mMockContext.getSystemServiceName(serviceClass)).thenReturn(serviceName);
+        when(mMockContext.getSystemService(serviceName)).thenReturn(service);
+    }
+
     @Test
     public void canRequireProvisioning() {
         setupForRequiredProvisioning();
@@ -285,8 +306,7 @@
     @Test
     public void toleratesCarrierConfigManagerMissing() {
         setupForRequiredProvisioning();
-        when(mContext.getSystemService(Context.CARRIER_CONFIG_SERVICE))
-            .thenReturn(null);
+        mockService(Context.CARRIER_CONFIG_SERVICE, CarrierConfigManager.class, null);
         mConfig = new FakeTetheringConfiguration(mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
         // Couldn't get the CarrierConfigManager, but still had a declared provisioning app.
         // Therefore provisioning still be required.
@@ -613,14 +633,16 @@
     @Test
     public void testCallStopTetheringWhenUiProvisioningFail() {
         setupForRequiredProvisioning();
-        verify(mEntitlementFailedListener, times(0)).onUiEntitlementFailed(TETHERING_WIFI);
+        verify(mTetherProvisioningFailedListener, times(0))
+                .onTetherProvisioningFailed(TETHERING_WIFI, FAILED_TETHERING_REASON);
         mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.notifyUpstream(true);
         mLooper.dispatchAll();
         mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
         mLooper.dispatchAll();
         assertEquals(1, mEnMgr.uiProvisionCount);
-        verify(mEntitlementFailedListener, times(1)).onUiEntitlementFailed(TETHERING_WIFI);
+        verify(mTetherProvisioningFailedListener, times(1))
+                .onTetherProvisioningFailed(TETHERING_WIFI, FAILED_TETHERING_REASON);
     }
 
     @Test
@@ -644,7 +666,8 @@
 
         // When second downstream is down, exempted downstream can use cellular upstream.
         assertEquals(1, mEnMgr.uiProvisionCount);
-        verify(mEntitlementFailedListener).onUiEntitlementFailed(TETHERING_USB);
+        verify(mTetherProvisioningFailedListener).onTetherProvisioningFailed(TETHERING_USB,
+                FAILED_TETHERING_REASON);
         mEnMgr.stopProvisioningIfNeeded(TETHERING_USB);
         assertTrue(mEnMgr.isCellularUpstreamPermitted());
 
@@ -678,4 +701,85 @@
         verify(mAlarmManager).setExact(eq(AlarmManager.ELAPSED_REALTIME_WAKEUP), anyLong(),
                 eq(mAlarmIntent));
     }
+
+    @Test
+    @IgnoreUpTo(SC_V2)
+    public void requestLatestTetheringEntitlementResult_carrierDoesNotSupport_noProvisionCount()
+            throws Exception {
+        setupForRequiredProvisioning();
+        setupCarrierConfig(false);
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
+        ResultReceiver receiver = new ResultReceiver(null) {
+            @Override
+            protected void onReceiveResult(int resultCode, Bundle resultData) {
+                assertEquals(TETHER_ERROR_PROVISIONING_FAILED, resultCode);
+            }
+        };
+        mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, false);
+        mLooper.dispatchAll();
+        assertEquals(0, mEnMgr.uiProvisionCount);
+        mEnMgr.reset();
+    }
+
+    @Test
+    @IgnoreUpTo(SC_V2)
+    public void reevaluateSimCardProvisioning_carrierUnsupportAndSimswitch() {
+        setupForRequiredProvisioning();
+
+        // Start a tethering with cellular data without provisioning.
+        mEnMgr.notifyUpstream(true);
+        mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, false);
+        mLooper.dispatchAll();
+
+        // Tear down mobile, then switch SIM.
+        mEnMgr.notifyUpstream(false);
+        mLooper.dispatchAll();
+        setupCarrierConfig(false);
+        mEnMgr.reevaluateSimCardProvisioning(mConfig);
+
+        // Turn on upstream.
+        mEnMgr.notifyUpstream(true);
+        mLooper.dispatchAll();
+
+        verify(mTetherProvisioningFailedListener)
+                .onTetherProvisioningFailed(TETHERING_WIFI, "Carrier does not support.");
+    }
+
+    @Test
+    @IgnoreUpTo(SC_V2)
+    public void startProvisioningIfNeeded_carrierUnsupport()
+            throws Exception {
+        setupForRequiredProvisioning();
+        setupCarrierConfig(false);
+        mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
+        verify(mTetherProvisioningFailedListener, never())
+                .onTetherProvisioningFailed(TETHERING_WIFI, "Carrier does not support.");
+
+        mEnMgr.notifyUpstream(true);
+        mLooper.dispatchAll();
+        verify(mTetherProvisioningFailedListener)
+                .onTetherProvisioningFailed(TETHERING_WIFI, "Carrier does not support.");
+        mEnMgr.stopProvisioningIfNeeded(TETHERING_WIFI);
+        reset(mTetherProvisioningFailedListener);
+
+        mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
+        mLooper.dispatchAll();
+        verify(mTetherProvisioningFailedListener)
+                .onTetherProvisioningFailed(TETHERING_WIFI, "Carrier does not support.");
+    }
+
+    @Test
+    public void isTetherProvisioningRequired_carrierUnSupport() {
+        setupForRequiredProvisioning();
+        setupCarrierConfig(false);
+        when(mResources.getStringArray(R.array.config_mobile_hotspot_provision_app))
+                .thenReturn(new String[0]);
+        mConfig = new FakeTetheringConfiguration(mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
+
+        if (SdkLevel.isAtLeastT()) {
+            assertTrue(mEnMgr.isTetherProvisioningRequired(mConfig));
+        } else {
+            assertFalse(mEnMgr.isTetherProvisioningRequired(mConfig));
+        }
+    }
 }
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
index fc34585..e9716b3 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
@@ -26,7 +26,7 @@
 import static android.net.RouteInfo.RTN_UNICAST;
 import static android.provider.Settings.Global.TETHER_OFFLOAD_DISABLED;
 
-import static com.android.modules.utils.build.SdkLevel.isAtLeastS;
+import static com.android.modules.utils.build.SdkLevel.isAtLeastT;
 import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_IFACE;
 import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_UID;
 import static com.android.networkstack.tethering.OffloadHardwareInterface.ForwardedStats;
@@ -666,10 +666,12 @@
         callback.onStoppedLimitReached();
         mTetherStatsProviderCb.expectNotifyStatsUpdated();
 
-        if (isAtLeastS()) {
+        if (isAtLeastT()) {
+            mTetherStatsProviderCb.expectNotifyLimitReached();
+        } else if (Build.VERSION.SDK_INT == Build.VERSION_CODES.S) {
             mTetherStatsProviderCb.expectNotifyWarningOrLimitReached();
         } else {
-            mTetherStatsProviderCb.expectLegacyNotifyLimitReached();
+            mTetherStatsProviderCb.expectNotifyLimitReached();
         }
     }
 
@@ -680,7 +682,12 @@
         final OffloadHardwareInterface.ControlCallback callback = mControlCallbackCaptor.getValue();
         callback.onWarningReached();
         mTetherStatsProviderCb.expectNotifyStatsUpdated();
-        mTetherStatsProviderCb.expectNotifyWarningOrLimitReached();
+
+        if (isAtLeastT()) {
+            mTetherStatsProviderCb.expectNotifyWarningReached();
+        } else {
+            mTetherStatsProviderCb.expectNotifyWarningOrLimitReached();
+        }
     }
 
     @Test
diff --git a/framework-t/api/module-lib-current.txt b/framework-t/api/module-lib-current.txt
index 75a8625..1bdd388 100644
--- a/framework-t/api/module-lib-current.txt
+++ b/framework-t/api/module-lib-current.txt
@@ -4,6 +4,7 @@
   public class NetworkStatsManager {
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void forceUpdate();
     method public static int getCollapsedRatType(int);
+    method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void noteUidForeground(int, boolean);
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void notifyNetworkStatus(@NonNull java.util.List<android.net.Network>, @NonNull java.util.List<android.net.NetworkStateSnapshot>, @Nullable String, @NonNull java.util.List<android.net.UnderlyingNetworkInfo>);
     method @NonNull @WorkerThread public android.app.usage.NetworkStats queryDetailsForDevice(@NonNull android.net.NetworkTemplate, long, long);
     method @NonNull @WorkerThread public android.app.usage.NetworkStats queryDetailsForUidTagState(@NonNull android.net.NetworkTemplate, long, long, int, int, int) throws java.lang.SecurityException;
@@ -15,7 +16,6 @@
     method public void setPollForce(boolean);
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void setPollOnOpen(boolean);
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void setStatsProviderWarningAndLimitAsync(@NonNull String, long, long);
-    method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK}) public void setUidForeground(int, boolean);
     field public static final int NETWORK_TYPE_5G_NSA = -2; // 0xfffffffe
   }
 
diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index 764cffa..bdefed1 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -236,6 +236,7 @@
   public abstract class NetworkAgent {
     ctor public NetworkAgent(@NonNull android.content.Context, @NonNull android.os.Looper, @NonNull String, @NonNull android.net.NetworkCapabilities, @NonNull android.net.LinkProperties, int, @NonNull android.net.NetworkAgentConfig, @Nullable android.net.NetworkProvider);
     ctor public NetworkAgent(@NonNull android.content.Context, @NonNull android.os.Looper, @NonNull String, @NonNull android.net.NetworkCapabilities, @NonNull android.net.LinkProperties, @NonNull android.net.NetworkScore, @NonNull android.net.NetworkAgentConfig, @Nullable android.net.NetworkProvider);
+    method public void destroyAndAwaitReplacement(@IntRange(from=0, to=0x1388) int);
     method @Nullable public android.net.Network getNetwork();
     method public void markConnected();
     method public void onAddKeepalivePacketFilter(int, @NonNull android.net.KeepalivePacketData);
diff --git a/framework/src/android/net/INetworkAgentRegistry.aidl b/framework/src/android/net/INetworkAgentRegistry.aidl
index 08536ca..2b22a5c 100644
--- a/framework/src/android/net/INetworkAgentRegistry.aidl
+++ b/framework/src/android/net/INetworkAgentRegistry.aidl
@@ -47,4 +47,5 @@
     void sendAddDscpPolicy(in DscpPolicy policy);
     void sendRemoveDscpPolicy(int policyId);
     void sendRemoveAllDscpPolicies();
+    void sendDestroyAndAwaitReplacement(int timeoutMillis);
 }
diff --git a/framework/src/android/net/NetworkAgent.java b/framework/src/android/net/NetworkAgent.java
index 945e670..fdc9081 100644
--- a/framework/src/android/net/NetworkAgent.java
+++ b/framework/src/android/net/NetworkAgent.java
@@ -434,6 +434,14 @@
      */
     public static final int CMD_DSCP_POLICY_STATUS = BASE + 28;
 
+    /**
+     * Sent by the NetworkAgent to ConnectivityService to notify that this network is expected to be
+     * replaced within the specified time by a similar network.
+     * arg1 = timeout in milliseconds
+     * @hide
+     */
+    public static final int EVENT_DESTROY_AND_AWAIT_REPLACEMENT = BASE + 29;
+
     private static NetworkInfo getLegacyNetworkInfo(final NetworkAgentConfig config) {
         final NetworkInfo ni = new NetworkInfo(config.legacyType, config.legacySubType,
                 config.legacyTypeName, config.legacySubTypeName);
@@ -943,6 +951,45 @@
     }
 
     /**
+     * Indicates that this agent will likely soon be replaced by another agent for a very similar
+     * network (e.g., same Wi-Fi SSID).
+     *
+     * If the network is not currently satisfying any {@link NetworkRequest}s, it will be torn down.
+     * If it is satisfying requests, then the native network corresponding to the agent will be
+     * destroyed immediately, but the agent will remain registered and will continue to satisfy
+     * requests until {@link #unregister} is called, the network is replaced by an equivalent or
+     * better network, or the specified timeout expires. During this time:
+     *
+     * <ul>
+     * <li>The agent may not send any further updates, for example by calling methods
+     *    such as {@link #sendNetworkCapabilities}, {@link #sendLinkProperties},
+     *    {@link #sendNetworkScore(NetworkScore)} and so on. Any such updates will be ignored.
+     * <li>The network will remain connected and continue to satisfy any requests that it would
+     *    otherwise satisfy (including, possibly, the default request).
+     * <li>The validation state of the network will not change, and calls to
+     *    {@link ConnectivityManager#reportNetworkConnectivity(Network, boolean)} will be ignored.
+     * </ul>
+     *
+     * Once this method is called, it is not possible to restore the agent to a functioning state.
+     * If a replacement network becomes available, then a new agent must be registered. When that
+     * replacement network is fully capable of replacing this network (including, possibly, being
+     * validated), this agent will no longer be needed and will be torn down. Otherwise, this agent
+     * can be disconnected by calling {@link #unregister}. If {@link #unregister} is not called,
+     * this agent will automatically be unregistered when the specified timeout expires. Any
+     * teardown delay previously set using{@link #setTeardownDelayMillis} is ignored.
+     *
+     * <p>This method has no effect if {@link #markConnected} has not yet been called.
+     * <p>This method may only be called once.
+     *
+     * @param timeoutMillis the timeout after which this network will be unregistered even if
+     *                      {@link #unregister} was not called.
+     */
+    public void destroyAndAwaitReplacement(
+            @IntRange(from = 0, to = MAX_TEARDOWN_DELAY_MS) int timeoutMillis) {
+        queueOrSendMessage(reg -> reg.sendDestroyAndAwaitReplacement(timeoutMillis));
+    }
+
+    /**
      * Change the legacy subtype of this network agent.
      *
      * This is only for backward compatibility and should not be used by non-legacy network agents,
diff --git a/framework/src/android/net/QosSession.java b/framework/src/android/net/QosSession.java
index 93f2ff2..25f3965 100644
--- a/framework/src/android/net/QosSession.java
+++ b/framework/src/android/net/QosSession.java
@@ -58,12 +58,12 @@
     }
 
     /**
-     * Gets the session id that is unique within that type.
+     * Gets the {@link QosSession} identifier which is set by the actor providing the QoS.
      * <p/>
-     * Note: The session id is set by the actor providing the qos.  It can be either manufactured by
-     * the actor, but also may have a particular meaning within that type.  For example, using the
-     * bearer id as the session id for {@link android.telephony.data.EpsBearerQosSessionAttributes}
-     * is a straight forward way to keep the sessions unique from one another within that type.
+     * Note: It can be either manufactured by the actor, but also may have a particular meaning
+     * within that type.  For example, using the bearer id as the session id for
+     * {@link android.telephony.data.EpsBearerQosSessionAttributes} is a straight forward way to
+     * keep the sessions unique from one another within that type.
      *
      * @return the id of the session
      */
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 418e4df..eb85120 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -3512,6 +3512,12 @@
         return false;
     }
 
+    private boolean isDisconnectRequest(Message msg) {
+        if (msg.what != NetworkAgent.EVENT_NETWORK_INFO_CHANGED) return false;
+        final NetworkInfo info = (NetworkInfo) ((Pair) msg.obj).second;
+        return info.getState() == NetworkInfo.State.DISCONNECTED;
+    }
+
     // must be stateless - things change under us.
     private class NetworkStateTrackerHandler extends Handler {
         public NetworkStateTrackerHandler(Looper looper) {
@@ -3528,6 +3534,11 @@
                 return;
             }
 
+            // If the network has been destroyed, the only thing that it can do is disconnect.
+            if (nai.destroyed && !isDisconnectRequest(msg)) {
+                return;
+            }
+
             switch (msg.what) {
                 case NetworkAgent.EVENT_NETWORK_CAPABILITIES_CHANGED: {
                     final NetworkCapabilities networkCapabilities = new NetworkCapabilities(
@@ -3629,12 +3640,60 @@
                     }
                     break;
                 }
+                case NetworkAgent.EVENT_DESTROY_AND_AWAIT_REPLACEMENT: {
+                    // If nai is not yet created, or is already destroyed, ignore.
+                    if (!shouldDestroyNativeNetwork(nai)) break;
+
+                    final int timeoutMs = (int) arg.second;
+                    if (timeoutMs < 0 || timeoutMs > NetworkAgent.MAX_TEARDOWN_DELAY_MS) {
+                        Log.e(TAG, "Invalid network replacement timer " + timeoutMs
+                                + ", must be between 0 and " + NetworkAgent.MAX_TEARDOWN_DELAY_MS);
+                    }
+
+                    // Marking a network awaiting replacement is used to ensure that any requests
+                    // satisfied by the network do not switch to another network until a
+                    // replacement is available or the wait for a replacement times out.
+                    // If the network is inactive (i.e., nascent or lingering), then there are no
+                    // such requests, and there is no point keeping it. Just tear it down.
+                    // Note that setLingerDuration(0) cannot be used to do this because the network
+                    // could be nascent.
+                    nai.clearInactivityState();
+                    if (unneeded(nai, UnneededFor.TEARDOWN)) {
+                        Log.d(TAG, nai.toShortString()
+                                + " marked awaiting replacement is unneeded, tearing down instead");
+                        teardownUnneededNetwork(nai);
+                        break;
+                    }
+
+                    Log.d(TAG, "Marking " + nai.toShortString()
+                            + " destroyed, awaiting replacement within " + timeoutMs + "ms");
+                    destroyNativeNetwork(nai);
+
+                    // TODO: deduplicate this call with the one in disconnectAndDestroyNetwork.
+                    // This is not trivial because KeepaliveTracker#handleStartKeepalive does not
+                    // consider the fact that the network could already have disconnected or been
+                    // destroyed. Fix the code to send ERROR_INVALID_NETWORK when this happens
+                    // (taking care to ensure no dup'd FD leaks), then remove the code duplication
+                    // and move this code to a sensible location (destroyNativeNetwork perhaps?).
+                    mKeepaliveTracker.handleStopAllKeepalives(nai,
+                            SocketKeepalive.ERROR_INVALID_NETWORK);
+
+                    nai.updateScoreForNetworkAgentUpdate();
+                    // This rematch is almost certainly not going to result in any changes, because
+                    // the destroyed flag is only just above the "current satisfier wins"
+                    // tie-breaker. But technically anything that affects scoring should rematch.
+                    rematchAllNetworksAndRequests();
+                    mHandler.postDelayed(() -> nai.disconnect(), timeoutMs);
+                    break;
+                }
             }
         }
 
         private boolean maybeHandleNetworkMonitorMessage(Message msg) {
             final int netId = msg.arg2;
             final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(netId);
+            // If a network has already been destroyed, all NetworkMonitor updates are ignored.
+            if (nai != null && nai.destroyed) return true;
             switch (msg.what) {
                 default:
                     return false;
@@ -4134,6 +4193,10 @@
         }
     }
 
+    private static boolean shouldDestroyNativeNetwork(@NonNull NetworkAgentInfo nai) {
+        return nai.created && !nai.destroyed;
+    }
+
     private void handleNetworkAgentDisconnected(Message msg) {
         NetworkAgentInfo nai = (NetworkAgentInfo) msg.obj;
         disconnectAndDestroyNetwork(nai);
@@ -4240,7 +4303,7 @@
     }
 
     private void destroyNetwork(NetworkAgentInfo nai) {
-        if (nai.created) {
+        if (shouldDestroyNativeNetwork(nai)) {
             // Tell netd to clean up the configuration for this network
             // (routing rules, DNS, etc).
             // This may be slow as it requires a lot of netd shelling out to ip and
@@ -4249,15 +4312,15 @@
             // network or service a new request from an app), so network traffic isn't interrupted
             // for an unnecessarily long time.
             destroyNativeNetwork(nai);
-            mDnsManager.removeNetwork(nai.network);
-
-            // clean up tc police filters on interface.
-            if (nai.everConnected && canNetworkBeRateLimited(nai) && mIngressRateLimit >= 0) {
-                mDeps.disableIngressRateLimit(nai.linkProperties.getInterfaceName());
-            }
+        }
+        if (!nai.created && !SdkLevel.isAtLeastT()) {
+            // Backwards compatibility: send onNetworkDestroyed even if network was never created.
+            // This can never run if the code above runs because shouldDestroyNativeNetwork is
+            // false if the network was never created.
+            // TODO: delete when S is no longer supported.
+            nai.onNetworkDestroyed();
         }
         mNetIdManager.releaseNetId(nai.network.getNetId());
-        nai.onNetworkDestroyed();
     }
 
     private boolean createNativeNetwork(@NonNull NetworkAgentInfo nai) {
@@ -4300,6 +4363,18 @@
         } catch (RemoteException | ServiceSpecificException e) {
             loge("Exception destroying network: " + e);
         }
+        // TODO: defer calling this until the network is removed from mNetworkAgentInfos.
+        // Otherwise, a private DNS configuration update for a destroyed network, or one that never
+        // gets created, could add data to DnsManager data structures that will never get deleted.
+        mDnsManager.removeNetwork(nai.network);
+
+        // clean up tc police filters on interface.
+        if (nai.everConnected && canNetworkBeRateLimited(nai) && mIngressRateLimit >= 0) {
+            mDeps.disableIngressRateLimit(nai.linkProperties.getInterfaceName());
+        }
+
+        nai.destroyed = true;
+        nai.onNetworkDestroyed();
     }
 
     // If this method proves to be too slow then we can maintain a separate
@@ -8552,11 +8627,19 @@
                     log("   accepting network in place of " + previousSatisfier.toShortString());
                 }
                 previousSatisfier.removeRequest(previousRequest.requestId);
-                if (canSupportGracefulNetworkSwitch(previousSatisfier, newSatisfier)) {
+                if (canSupportGracefulNetworkSwitch(previousSatisfier, newSatisfier)
+                        && !previousSatisfier.destroyed) {
                     // If this network switch can't be supported gracefully, the request is not
                     // lingered. This allows letting go of the network sooner to reclaim some
                     // performance on the new network, since the radio can't do both at the same
                     // time while preserving good performance.
+                    //
+                    // Also don't linger the request if the old network has been destroyed.
+                    // A destroyed network does not provide actual network connectivity, so
+                    // lingering it is not useful. In particular this ensures that a destroyed
+                    // network is outscored by its replacement,
+                    // then it is torn down immediately instead of being lingered, and any apps that
+                    // were using it immediately get onLost and can connect using the new network.
                     previousSatisfier.lingerRequest(previousRequest.requestId, now);
                 }
             } else {
diff --git a/service/src/com/android/server/connectivity/Nat464Xlat.java b/service/src/com/android/server/connectivity/Nat464Xlat.java
index c66a280..7b06682 100644
--- a/service/src/com/android/server/connectivity/Nat464Xlat.java
+++ b/service/src/com/android/server/connectivity/Nat464Xlat.java
@@ -132,8 +132,8 @@
         final boolean skip464xlat = (nai.netAgentConfig() != null)
                 && nai.netAgentConfig().skip464xlat;
 
-        return supported && connected && isIpv6OnlyNetwork && !skip464xlat
-            && (nai.networkCapabilities.hasTransport(TRANSPORT_CELLULAR)
+        return supported && connected && isIpv6OnlyNetwork && !skip464xlat && !nai.destroyed
+                && (nai.networkCapabilities.hasTransport(TRANSPORT_CELLULAR)
                 ? isCellular464XlatEnabled() : true);
     }
 
diff --git a/service/src/com/android/server/connectivity/NetworkAgentInfo.java b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
index e29d616..ee45e5c 100644
--- a/service/src/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
@@ -732,6 +732,12 @@
             mHandler.obtainMessage(NetworkAgent.EVENT_REMOVE_ALL_DSCP_POLICIES,
                     new Pair<>(NetworkAgentInfo.this, null)).sendToTarget();
         }
+
+        @Override
+        public void sendDestroyAndAwaitReplacement(final int timeoutMillis) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_DESTROY_AND_AWAIT_REPLACEMENT,
+                    new Pair<>(NetworkAgentInfo.this, timeoutMillis)).sendToTarget();
+        }
     }
 
     /**
@@ -976,7 +982,7 @@
     /**
      * Update the ConnectivityService-managed bits in the score.
      *
-     * Call this after updating the network agent config.
+     * Call this after changing any data that might affect the score (e.g., agent config).
      */
     public void updateScoreForNetworkAgentUpdate() {
         mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig,
@@ -1256,6 +1262,8 @@
                 + "network{" + network + "}  handle{" + network.getNetworkHandle() + "}  ni{"
                 + networkInfo.toShortString() + "} "
                 + mScore + " "
+                + (created ? " created" : "")
+                + (destroyed ? " destroyed" : "")
                 + (isNascent() ? " nascent" : (isLingering() ? " lingering" : ""))
                 + (everValidated ? " everValidated" : "")
                 + (lastValidated ? " lastValidated" : "")
diff --git a/tests/cts/net/src/android/net/cts/IpSecManagerTest.java b/tests/cts/net/src/android/net/cts/IpSecManagerTest.java
index 7bce3d2..8234ec1 100644
--- a/tests/cts/net/src/android/net/cts/IpSecManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/IpSecManagerTest.java
@@ -52,6 +52,7 @@
 
 import static com.android.compatibility.common.util.PropertyUtil.getFirstApiLevel;
 import static com.android.compatibility.common.util.PropertyUtil.getVendorApiLevel;
+import static com.android.testutils.MiscAsserts.assertThrows;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -129,12 +130,11 @@
             assertTrue("Failed to allocate specified SPI, " + DROID_SPI,
                     droidSpi.getSpi() == DROID_SPI);
 
-            try {
-                mISM.allocateSecurityParameterIndex(addr, DROID_SPI);
-                fail("Duplicate SPI was allowed to be created");
-            } catch (IpSecManager.SpiUnavailableException expected) {
-                // This is a success case because we expect a dupe SPI to throw
-            }
+            IpSecManager.SpiUnavailableException expectedException =
+                    assertThrows("Duplicate SPI was allowed to be created",
+                            IpSecManager.SpiUnavailableException.class,
+                            () -> mISM.allocateSecurityParameterIndex(addr, DROID_SPI));
+            assertEquals(expectedException.getSpi(), droidSpi.getSpi());
 
             randomSpi.close();
             droidSpi.close();
diff --git a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
index 225602f..af567ff 100644
--- a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
+++ b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
@@ -19,6 +19,7 @@
 import android.app.Instrumentation
 import android.content.Context
 import android.net.ConnectivityManager
+import android.net.EthernetNetworkSpecifier
 import android.net.INetworkAgent
 import android.net.INetworkAgentRegistry
 import android.net.InetAddresses
@@ -35,6 +36,7 @@
 import android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_CONGESTED
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_METERED
+import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED
 import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VCN_MANAGED
@@ -42,7 +44,9 @@
 import android.net.NetworkCapabilities.NET_CAPABILITY_TEMPORARILY_NOT_METERED
 import android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED
 import android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED
+import android.net.NetworkCapabilities.TRANSPORT_CELLULAR
 import android.net.NetworkCapabilities.TRANSPORT_TEST
+import android.net.NetworkCapabilities.TRANSPORT_WIFI
 import android.net.NetworkCapabilities.TRANSPORT_VPN
 import android.net.NetworkInfo
 import android.net.NetworkProvider
@@ -100,6 +104,7 @@
 import com.android.testutils.TestableNetworkAgent.CallbackEntry.OnUnregisterQosCallback
 import com.android.testutils.TestableNetworkAgent.CallbackEntry.OnValidationStatus
 import com.android.testutils.TestableNetworkCallback
+import com.android.testutils.assertThrows
 import org.junit.After
 import org.junit.Assume.assumeFalse
 import org.junit.Before
@@ -112,6 +117,8 @@
 import org.mockito.Mockito.mock
 import org.mockito.Mockito.timeout
 import org.mockito.Mockito.verify
+import java.io.IOException
+import java.net.DatagramSocket
 import java.net.InetAddress
 import java.net.InetSocketAddress
 import java.net.Socket
@@ -249,6 +256,28 @@
                 .build()
     }
 
+    private fun makeTestNetworkCapabilities(
+        specifier: String? = null,
+        transports: IntArray = intArrayOf()
+    ) = NetworkCapabilities().apply {
+        addTransportType(TRANSPORT_TEST)
+        removeCapability(NET_CAPABILITY_TRUSTED)
+        removeCapability(NET_CAPABILITY_INTERNET)
+        addCapability(NET_CAPABILITY_NOT_SUSPENDED)
+        addCapability(NET_CAPABILITY_NOT_ROAMING)
+        addCapability(NET_CAPABILITY_NOT_VPN)
+        if (SdkLevel.isAtLeastS()) {
+            addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
+        }
+        if (null != specifier) {
+            setNetworkSpecifier(CompatUtil.makeEthernetNetworkSpecifier(specifier))
+        }
+        for (t in transports) { addTransportType(t) }
+        // Most transports are not allowed on test networks unless the network is marked restricted.
+        // This test does not need
+        if (transports.size > 0) removeCapability(NET_CAPABILITY_NOT_RESTRICTED)
+    }
+
     private fun createNetworkAgent(
         context: Context = realContext,
         specifier: String? = null,
@@ -256,20 +285,7 @@
         initialLp: LinkProperties? = null,
         initialConfig: NetworkAgentConfig? = null
     ): TestableNetworkAgent {
-        val nc = initialNc ?: NetworkCapabilities().apply {
-            addTransportType(TRANSPORT_TEST)
-            removeCapability(NET_CAPABILITY_TRUSTED)
-            removeCapability(NET_CAPABILITY_INTERNET)
-            addCapability(NET_CAPABILITY_NOT_SUSPENDED)
-            addCapability(NET_CAPABILITY_NOT_ROAMING)
-            addCapability(NET_CAPABILITY_NOT_VPN)
-            if (SdkLevel.isAtLeastS()) {
-                addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
-            }
-            if (null != specifier) {
-                setNetworkSpecifier(CompatUtil.makeEthernetNetworkSpecifier(specifier))
-            }
-        }
+        val nc = initialNc ?: makeTestNetworkCapabilities(specifier)
         val lp = initialLp ?: LinkProperties().apply {
             addLinkAddress(LinkAddress(LOCAL_IPV4_ADDRESS, 32))
             addRoute(RouteInfo(IpPrefix("0.0.0.0/0"), null, null))
@@ -284,12 +300,14 @@
         context: Context = realContext,
         specifier: String? = UUID.randomUUID().toString(),
         initialConfig: NetworkAgentConfig? = null,
-        expectedInitSignalStrengthThresholds: IntArray? = intArrayOf()
+        expectedInitSignalStrengthThresholds: IntArray? = intArrayOf(),
+        transports: IntArray = intArrayOf()
     ): Pair<TestableNetworkAgent, TestableNetworkCallback> {
         val callback = TestableNetworkCallback()
         // Ensure this NetworkAgent is never unneeded by filing a request with its specifier.
         requestNetwork(makeTestNetworkRequest(specifier = specifier), callback)
-        val agent = createNetworkAgent(context, specifier, initialConfig = initialConfig)
+        val nc = makeTestNetworkCapabilities(specifier, transports)
+        val agent = createNetworkAgent(context, initialConfig = initialConfig, initialNc = nc)
         agent.setTeardownDelayMillis(0)
         // Connect the agent and verify initial status callbacks.
         agent.register()
@@ -301,6 +319,15 @@
         return agent to callback
     }
 
+    private fun connectNetwork(vararg transports: Int): Pair<TestableNetworkAgent, Network> {
+        val (agent, callback) = createConnectedNetworkAgent(transports = transports)
+        val network = agent.network!!
+        // createConnectedNetworkAgent internally files a request; release it so that the network
+        // will be torn down if unneeded.
+        mCM.unregisterNetworkCallback(callback)
+        return agent to network
+    }
+
     private fun createNetworkAgentWithFakeCS() = createNetworkAgent().also {
         mFakeConnectivityService.connect(it.registerForTest(Network(FAKE_NET_ID)))
     }
@@ -1123,4 +1150,138 @@
                 remoteAddresses
         )
     }
+
+    @Test
+    fun testDestroyAndAwaitReplacement() {
+        // Keeps an eye on all test networks.
+        val matchAllCallback = TestableNetworkCallback(timeoutMs = DEFAULT_TIMEOUT_MS)
+        registerNetworkCallback(makeTestNetworkRequest(), matchAllCallback)
+
+        // File a request that matches and keeps up the best-scoring test network.
+        val testCallback = TestableNetworkCallback(timeoutMs = DEFAULT_TIMEOUT_MS)
+        requestNetwork(makeTestNetworkRequest(), testCallback)
+
+        // Connect the first network. This should satisfy the request.
+        val (agent1, network1) = connectNetwork()
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network1)
+        testCallback.expectAvailableThenValidatedCallbacks(network1)
+        // Check that network1 exists by binding a socket to it and getting no exceptions.
+        network1.bindSocket(DatagramSocket())
+
+        // Connect a second agent. network1 is preferred because it was already registered, so
+        // testCallback will not see any events. agent2 is be torn down because it has no requests.
+        val (agent2, network2) = connectNetwork()
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network2)
+        matchAllCallback.expectCallback<Lost>(network2)
+        agent2.expectCallback<OnNetworkUnwanted>()
+        agent2.expectCallback<OnNetworkDestroyed>()
+        assertNull(mCM.getLinkProperties(network2))
+
+        // Mark the first network as awaiting replacement. This should destroy the underlying
+        // native network and send onNetworkDestroyed, but will not send any NetworkCallbacks,
+        // because for callback and scoring purposes network1 is still connected.
+        agent1.destroyAndAwaitReplacement(5_000 /* timeoutMillis */)
+        agent1.expectCallback<OnNetworkDestroyed>()
+        assertThrows(IOException::class.java) { network1.bindSocket(DatagramSocket()) }
+        assertNotNull(mCM.getLinkProperties(network1))
+
+        // Calling destroyAndAwaitReplacement more than once has no effect.
+        // If it did, this test would fail because the 1ms timeout means that the network would be
+        // torn down before the replacement arrives.
+        agent1.destroyAndAwaitReplacement(1 /* timeoutMillis */)
+
+        // Connect a third network. Because network1 is awaiting replacement, network3 is preferred
+        // as soon as it validates (until then, it is outscored by network1).
+        // The fact that the first events seen by matchAllCallback is the connection of network3
+        // implicitly ensures that no callbacks are sent since network1 was lost.
+        val (agent3, network3) = connectNetwork()
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network3)
+        testCallback.expectAvailableDoubleValidatedCallbacks(network3)
+
+        // As soon as the replacement arrives, network1 is disconnected.
+        // Check that this happens before the replacement timeout (5 seconds) fires.
+        matchAllCallback.expectCallback<Lost>(network1, 2_000 /* timeoutMs */)
+        agent1.expectCallback<OnNetworkUnwanted>()
+
+        // Test lingering:
+        // - Connect a higher-scoring network and check that network3 starts lingering.
+        // - Mark network3 awaiting replacement.
+        // - Check that network3 is torn down immediately without waiting for the linger timer or
+        //   the replacement timer to fire. This is a regular teardown, so it results in
+        //   onNetworkUnwanted before onNetworkDestroyed.
+        val (agent4, agent4callback) = createConnectedNetworkAgent()
+        val network4 = agent4.network!!
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network4)
+        agent4.sendNetworkScore(NetworkScore.Builder().setTransportPrimary(true).build())
+        matchAllCallback.expectCallback<Losing>(network3)
+        testCallback.expectAvailableCallbacks(network4, validated = true)
+        mCM.unregisterNetworkCallback(agent4callback)
+        agent3.destroyAndAwaitReplacement(5_000)
+        agent3.expectCallback<OnNetworkUnwanted>()
+        matchAllCallback.expectCallback<Lost>(network3, 1000L)
+        agent3.expectCallback<OnNetworkDestroyed>()
+
+        // Now mark network4 awaiting replacement with a low timeout, and check that if no
+        // replacement arrives, it is torn down.
+        agent4.destroyAndAwaitReplacement(100 /* timeoutMillis */)
+        matchAllCallback.expectCallback<Lost>(network4, 1000L /* timeoutMs */)
+        testCallback.expectCallback<Lost>(network4, 1000L /* timeoutMs */)
+        agent4.expectCallback<OnNetworkDestroyed>()
+        agent4.expectCallback<OnNetworkUnwanted>()
+
+        // If a network that is awaiting replacement is unregistered, it disconnects immediately,
+        // before the replacement timeout fires.
+        val (agent5, network5) = connectNetwork()
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network5)
+        testCallback.expectAvailableThenValidatedCallbacks(network5)
+        agent5.destroyAndAwaitReplacement(5_000 /* timeoutMillis */)
+        agent5.unregister()
+        matchAllCallback.expectCallback<Lost>(network5, 1000L /* timeoutMs */)
+        testCallback.expectCallback<Lost>(network5, 1000L /* timeoutMs */)
+        agent5.expectCallback<OnNetworkDestroyed>()
+        agent5.expectCallback<OnNetworkUnwanted>()
+
+        // If wifi is replaced within the timeout, the device does not switch to cellular.
+        val (cellAgent, cellNetwork) = connectNetwork(TRANSPORT_CELLULAR)
+        testCallback.expectAvailableThenValidatedCallbacks(cellNetwork)
+        matchAllCallback.expectAvailableThenValidatedCallbacks(cellNetwork)
+
+        val (wifiAgent, wifiNetwork) = connectNetwork(TRANSPORT_WIFI)
+        testCallback.expectAvailableCallbacks(wifiNetwork, validated = true)
+        testCallback.expectCapabilitiesThat(wifiNetwork) {
+            it.hasCapability(NET_CAPABILITY_VALIDATED)
+        }
+        matchAllCallback.expectAvailableCallbacks(wifiNetwork, validated = false)
+        matchAllCallback.expectCallback<Losing>(cellNetwork)
+        matchAllCallback.expectCapabilitiesThat(wifiNetwork) {
+            it.hasCapability(NET_CAPABILITY_VALIDATED)
+        }
+
+        wifiAgent.destroyAndAwaitReplacement(5_000 /* timeoutMillis */)
+        wifiAgent.expectCallback<OnNetworkDestroyed>()
+
+        // Once the network is awaiting replacement, changing LinkProperties, NetworkCapabilities or
+        // score, or calling reportNetworkConnectivity, have no effect.
+        val wifiSpecifier = mCM.getNetworkCapabilities(wifiNetwork)!!.networkSpecifier
+        assertNotNull(wifiSpecifier)
+        assertTrue(wifiSpecifier is EthernetNetworkSpecifier)
+
+        val wifiNc = makeTestNetworkCapabilities(wifiSpecifier.interfaceName,
+                intArrayOf(TRANSPORT_WIFI))
+        wifiAgent.sendNetworkCapabilities(wifiNc)
+        val wifiLp = mCM.getLinkProperties(wifiNetwork)!!
+        val newRoute = RouteInfo(IpPrefix("192.0.2.42/24"))
+        assertFalse(wifiLp.getRoutes().contains(newRoute))
+        wifiLp.addRoute(newRoute)
+        wifiAgent.sendLinkProperties(wifiLp)
+        mCM.reportNetworkConnectivity(wifiNetwork, false)
+        // The test implicitly checks that no callbacks are sent here, because the next events seen
+        // by the callbacks are for the new network connecting.
+
+        val (newWifiAgent, newWifiNetwork) = connectNetwork(TRANSPORT_WIFI)
+        testCallback.expectAvailableCallbacks(newWifiNetwork, validated = true)
+        matchAllCallback.expectAvailableThenValidatedCallbacks(newWifiNetwork)
+        matchAllCallback.expectCallback<Lost>(wifiNetwork)
+        wifiAgent.expectCallback<OnNetworkUnwanted>()
+    }
 }
diff --git a/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java b/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
index aa4e4bb..ceeb997 100644
--- a/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
+++ b/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
@@ -517,10 +517,10 @@
                 .insertEntry(TEST_IFACE, UID_RED, SET_FOREGROUND, TAG_NONE, 512L, 4L, 256L, 2L, 0L)
                 .insertEntry(TEST_IFACE, UID_RED, SET_FOREGROUND, 0xFAAD, 256L, 2L, 128L, 1L, 0L)
                 .insertEntry(TEST_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 128L, 1L, 128L, 1L, 0L));
-        mService.setUidForeground(UID_RED, false);
+        mService.noteUidForeground(UID_RED, false);
         verify(mUidCounterSetMap, never()).deleteEntry(any());
         mService.incrementOperationCount(UID_RED, 0xFAAD, 4);
-        mService.setUidForeground(UID_RED, true);
+        mService.noteUidForeground(UID_RED, true);
         verify(mUidCounterSetMap).updateEntry(
                 eq(new U32(UID_RED)), eq(new U8((short) SET_FOREGROUND)));
         mService.incrementOperationCount(UID_RED, 0xFAAD, 6);
@@ -1118,7 +1118,7 @@
                 .insertEntry(TEST_IFACE, UID_RED, SET_DEFAULT, 0xF00D, 64L, 1L, 64L, 1L, 0L)
                 .insertEntry(TEST_IFACE, UID_RED, SET_FOREGROUND, TAG_NONE, 32L, 2L, 32L, 2L, 0L)
                 .insertEntry(TEST_IFACE, UID_RED, SET_FOREGROUND, 0xFAAD, 1L, 1L, 1L, 1L, 0L));
-        mService.setUidForeground(UID_RED, true);
+        mService.noteUidForeground(UID_RED, true);
         verify(mUidCounterSetMap).updateEntry(
                 eq(new U32(UID_RED)), eq(new U8((short) SET_FOREGROUND)));
         mService.incrementOperationCount(UID_RED, 0xFAAD, 1);