diff --git a/src/com/android/phone/vvm/omtp/fetch/FetchVoicemailReceiver.java b/src/com/android/phone/vvm/omtp/fetch/FetchVoicemailReceiver.java
index 83e9633..43724e4 100644
--- a/src/com/android/phone/vvm/omtp/fetch/FetchVoicemailReceiver.java
+++ b/src/com/android/phone/vvm/omtp/fetch/FetchVoicemailReceiver.java
@@ -135,6 +135,12 @@
                 public void run() {
                     while (mRetryCount > 0) {
                         ImapHelper imapHelper = new ImapHelper(mContext, mPhoneAccount, network);
+                        if (!imapHelper.isSuccessfullyInitialized()) {
+                            Log.w(TAG, "Can't retrieve Imap credentials.");
+                            releaseNetwork();
+                            return;
+                        }
+
                         boolean success = imapHelper.fetchVoicemailPayload(
                                 new VoicemailFetchedCallback(mContext, mUri), mUid);
                         if (!success && mRetryCount > 0) {
diff --git a/src/com/android/phone/vvm/omtp/imap/ImapHelper.java b/src/com/android/phone/vvm/omtp/imap/ImapHelper.java
index b40cf1e..1d20dbd 100644
--- a/src/com/android/phone/vvm/omtp/imap/ImapHelper.java
+++ b/src/com/android/phone/vvm/omtp/imap/ImapHelper.java
@@ -79,10 +79,19 @@
             mImapStore = new ImapStore(
                     context, username, password, port, serverName, ImapStore.FLAG_NONE, network);
         } catch (NumberFormatException e) {
-            LogUtils.e(TAG, e, "Could not parse port number");
+            LogUtils.w(TAG, "Could not parse port number");
         }
     }
 
+    /**
+     * If mImapStore is null, this means that there was a missing or badly formatted port number,
+     * which means there aren't sufficient credentials for login. If mImapStore is succcessfully
+     * initialized, then ImapHelper is ready to go.
+     */
+    public boolean isSuccessfullyInitialized() {
+        return mImapStore != null;
+    }
+
     /** The caller thread will block until the method returns. */
     public boolean markMessagesAsRead(List<Voicemail> voicemails) {
         return setFlags(voicemails, Flag.SEEN);
diff --git a/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java b/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
index d96f058..d0c6231 100644
--- a/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
+++ b/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
@@ -200,6 +200,15 @@
                 downloadSuccess = true;
 
                 ImapHelper imapHelper = new ImapHelper(mContext, mPhoneAccount, network);
+
+                if (!imapHelper.isSuccessfullyInitialized()) {
+                    Log.w(TAG, "Can't retrieve Imap credentials.");
+                    releaseNetwork(this);
+                    VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(mContext,
+                            mPhoneAccount);
+                    return;
+                }
+
                 if (SYNC_FULL_SYNC.equals(mAction) || SYNC_UPLOAD_ONLY.equals(mAction)) {
                     uploadSuccess = upload(imapHelper);
                 }
diff --git a/src/com/android/phone/vvm/omtp/sync/VvmPhoneStateListener.java b/src/com/android/phone/vvm/omtp/sync/VvmPhoneStateListener.java
index d4b84d4..84449d7 100644
--- a/src/com/android/phone/vvm/omtp/sync/VvmPhoneStateListener.java
+++ b/src/com/android/phone/vvm/omtp/sync/VvmPhoneStateListener.java
@@ -55,7 +55,9 @@
                             true /* firstAttempt */);
                     mContext.startService(serviceIntent);
                 }
-            } else {
+            }
+
+            if (!OmtpVvmSourceManager.getInstance(mContext).isVvmSourceRegistered(mPhoneAccount)) {
                 OmtpVvmCarrierConfigHelper carrierConfigHelper = new OmtpVvmCarrierConfigHelper(
                         mContext, PhoneUtils.getSubIdForPhoneAccountHandle(mPhoneAccount));
                 carrierConfigHelper.startActivation();