diff --git a/channels/chan_sip.c b/channels/chan_sip.c index de46b9b447..eca31b6fc4 100644 --- a/channels/chan_sip.c +++ b/channels/chan_sip.c @@ -14812,6 +14812,18 @@ static int handle_request_subscribe(struct sip_pvt *p, struct sip_request *req, } if (!ast_test_flag(req, SIP_PKT_IGNORE) && !resubscribe) { /* Set up dialog, new subscription */ + const char *to = get_header(req, "To"); + char totag[128]; + + /* Check to see if a tag was provided, if so this is actually a resubscription of a dialog we no longer know about */ + if (!ast_strlen_zero(to) && gettag(req, "To", totag, sizeof(totag))) { + if (ast_test_flag(req, SIP_PKT_DEBUG)) + ast_verbose("Received resubscription for a dialog we no longer know about. Telling remote side to subscribe again.\n"); + transmit_response(p, "481 Subscription does not exist", req); + ast_set_flag(&p->flags[0], SIP_NEEDDESTROY); + return 0; + } + /* Use this as the basis */ if (ast_test_flag(req, SIP_PKT_DEBUG)) ast_verbose("Creating new subscription\n");