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))
+               return 0;

        peer->lastmsgcheck = time(NULL);