Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c (revision 286645)
+++ channels/chan_sip.c (working copy)
@@ -16850,7 +16850,8 @@
                return 0;

        /* Check for messages */
-       ast_app_inboxcount(peer->mailbox, &newmsgs, &oldmsgs);
+       if (ast_app_inboxcount(peer->mailbox, &newmsgs, &oldmsgs) == -1)
+               return 0;

        peer->lastmsgcheck = time(NULL);

Index: main/app.c
===================================================================
--- main/app.c  (revision 286645)
+++ main/app.c  (working copy)
@@ -194,7 +194,7 @@
                ast_verbose(VERBOSE_PREFIX_3 "Message count requested for mailbox %s but voicemail not loaded.\n", mailbox);
        }

-       return 0;
+       return -1;
 }

 int ast_app_messagecount(const char *context, const char *mailbox, const char *folder)