Fix a bug where using immediate with mISDN caused a cause code of 16 to get sent back instead of 1 if the 's' extension did not exist.

(closes issue #12286)
Reported by: lmamane


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@196116 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_misdn.c

@@ -3785,9 +3785,10 @@ static void do_immediate_setup(struct misdn_bchannel *bc, struct chan_list *ch,
 	chan_misdn_log(1, bc->port, "* Starting Ast ctx:%s dad:%s oad:%s with 's' extension\n", ast->context, ast->exten, ast->cid.cid_num);
   
 	strcpy(ast->exten, "s");
-  
-	if (pbx_start_chan(ch) < 0) {
+ 
+	if (!ast_canmatch_extension(ast, ast->context, ast->exten, 1, bc->oad) || pbx_start_chan(ch) < 0) {
 		ast = NULL;
+		bc->out_cause = AST_CAUSE_UNALLOCATED;
 		hangup_chan(ch);
 		hanguptone_indicate(ch);