Don't care if the extension given doesn't exist for subscription based MWI.

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@103763 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -14863,7 +14863,7 @@ static int handle_request_subscribe(struct sip_pvt *p, struct sip_request *req,
 	parse_ok_contact(p, req);
 
 	build_contact(p);
-	if (gotdest) {
+	if (strcmp(event, "message-summary") && gotdest) {
 		transmit_response(p, "404 Not Found", req);
 		ast_set_flag(&p->flags[0], SIP_NEEDDESTROY);	
 		if (authpeer)