diff --git a/channels/chan_misdn.c b/channels/chan_misdn.c
index 0fc1a5b3b9..cc35490177 100644
--- a/channels/chan_misdn.c
+++ b/channels/chan_misdn.c
@@ -4058,8 +4058,9 @@ static void do_immediate_setup(struct misdn_bchannel *bc, struct chan_list *ch,
   
 	strncpy(ast->exten, "s", 2);
   
-	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);