diff --git a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java b/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
index 3dcc15f..78131ab 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
@@ -306,28 +306,22 @@
         mTetheringRestriction = new UserRestrictionActionListener(userManager, this);
         mExecutor = new TetheringThreadExecutor(mHandler);
         mActiveDataSubIdListener = new ActiveDataSubIdListener(mExecutor);
+        mNetdCallback = new NetdCallback();
 
         // Load tethering configuration.
         updateConfiguration();
-        // NetdCallback should be registered after updateConfiguration() to ensure
-        // TetheringConfiguration is created.
-        mNetdCallback = new NetdCallback();
+    }
+
+    /**
+     * Start to register callbacks.
+     * Call this function when tethering is ready to handle callback events.
+     */
+    public void startStateMachineUpdaters() {
         try {
             mNetd.registerUnsolicitedEventListener(mNetdCallback);
         } catch (RemoteException e) {
             mLog.e("Unable to register netd UnsolicitedEventListener");
         }
-
-        startStateMachineUpdaters(mHandler);
-        startTrackDefaultNetwork();
-
-        final WifiManager wifiManager = getWifiManager();
-        if (wifiManager != null) {
-            wifiManager.registerSoftApCallback(mExecutor, new TetheringSoftApCallback());
-        }
-    }
-
-    private void startStateMachineUpdaters(Handler handler) {
         mCarrierConfigChange.startListening();
         mContext.getSystemService(TelephonyManager.class).listen(mActiveDataSubIdListener,
                 PhoneStateListener.LISTEN_ACTIVE_DATA_SUBSCRIPTION_ID_CHANGE);
@@ -340,7 +334,14 @@
         filter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
         filter.addAction(UserManager.ACTION_USER_RESTRICTIONS_CHANGED);
         filter.addAction(ACTION_RESTRICT_BACKGROUND_CHANGED);
-        mContext.registerReceiver(mStateReceiver, filter, null, handler);
+        mContext.registerReceiver(mStateReceiver, filter, null, mHandler);
+
+        final WifiManager wifiManager = getWifiManager();
+        if (wifiManager != null) {
+            wifiManager.registerSoftApCallback(mExecutor, new TetheringSoftApCallback());
+        }
+
+        startTrackDefaultNetwork();
     }
 
     private class TetheringThreadExecutor implements Executor {
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
index c5329d8..c30be25 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
@@ -80,6 +80,7 @@
         mContext = mDeps.getContext();
         mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
         mTethering = makeTethering(mDeps);
+        mTethering.startStateMachineUpdaters();
     }
 
     /**
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
index d983fae..a99ca8d 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
@@ -485,6 +485,7 @@
         mServiceContext.registerReceiver(mBroadcastReceiver,
                 new IntentFilter(ACTION_TETHER_STATE_CHANGED));
         mTethering = makeTethering();
+        mTethering.startStateMachineUpdaters();
         verify(mStatsManager, times(1)).registerNetworkStatsProvider(anyString(), any());
         verify(mNetd).registerUnsolicitedEventListener(any());
         final ArgumentCaptor<PhoneStateListener> phoneListenerCaptor =