diff --git a/src/com/android/phone/PhoneGlobals.java b/src/com/android/phone/PhoneGlobals.java
index 4ff8d8e..2d87e78 100644
--- a/src/com/android/phone/PhoneGlobals.java
+++ b/src/com/android/phone/PhoneGlobals.java
@@ -45,7 +45,6 @@
 import android.telephony.SubscriptionManager;
 import android.util.Log;
 import android.widget.Toast;
-
 import com.android.internal.telephony.Call;
 import com.android.internal.telephony.CallManager;
 import com.android.internal.telephony.IccCardConstants;
@@ -850,6 +849,11 @@
     public void clearMwiIndicator(int subId) {
         // Setting voiceMessageCount to 0 will remove the current notification and clear the system
         // cached value.
-        getPhone(subId).setVoiceMessageCount(0);
+        Phone phone = getPhone(subId);
+        if (phone == null) {
+            Log.w(LOG_TAG, "clearMwiIndicator on null phone, subId:" + subId);
+        } else {
+            phone.setVoiceMessageCount(0);
+        }
     }
 }
diff --git a/src/com/android/phone/vvm/omtp/VvmPhoneStateListener.java b/src/com/android/phone/vvm/omtp/VvmPhoneStateListener.java
index f64d15b..94e616c 100644
--- a/src/com/android/phone/vvm/omtp/VvmPhoneStateListener.java
+++ b/src/com/android/phone/vvm/omtp/VvmPhoneStateListener.java
@@ -19,6 +19,7 @@
 import android.telecom.PhoneAccountHandle;
 import android.telephony.PhoneStateListener;
 import android.telephony.ServiceState;
+import android.telephony.SubscriptionManager;
 import com.android.phone.PhoneGlobals;
 import com.android.phone.PhoneUtils;
 import com.android.phone.VoicemailStatus;
@@ -47,6 +48,13 @@
 
     @Override
     public void onServiceStateChanged(ServiceState serviceState) {
+        int subId = PhoneAccountHandleConverter.toSubId(mPhoneAccount);
+        if (!SubscriptionManager.isValidSubscriptionId(subId)) {
+            VvmLog.e(TAG, "onServiceStateChanged on phoneAccount " + mPhoneAccount
+                    + " with invalid subId, ignoring");
+            return;
+        }
+
         int state = serviceState.getState();
         if (state == mPreviousState || (state != ServiceState.STATE_IN_SERVICE
                 && mPreviousState != ServiceState.STATE_IN_SERVICE)) {
@@ -56,7 +64,6 @@
             return;
         }
 
-        int subId = PhoneAccountHandleConverter.toSubId(mPhoneAccount);
         OmtpVvmCarrierConfigHelper helper = new OmtpVvmCarrierConfigHelper(mContext, subId);
 
         if (state == ServiceState.STATE_IN_SERVICE) {