Index: channels/chan_misdn.c
===================================================================
--- channels/chan_misdn.c	(revision 312069)
+++ channels/chan_misdn.c	(working copy)
@@ -681,7 +681,7 @@
 static enum event_response_e
 cb_events(enum event_e event, struct misdn_bchannel *bc, void *user_data);
 
-static void send_cause2ast(struct ast_channel *ast, struct misdn_bchannel*bc, struct chan_list *ch);
+static int send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch);
 
 static void cl_queue_chan(struct chan_list *chan);
 
@@ -8364,8 +8364,7 @@
 		cb_log(2, port, " --> hangup\n");
 		ch->need_hangup = 0;
 		ch->need_queue_hangup = 0;
-		if (ch->ast) {
-			send_cause2ast(ch->ast, bc, ch);
+		if (ch->ast && send_cause2ast(ch->ast, bc, ch)) {
 			ast_hangup(ch->ast);
 		}
 		return;
@@ -8373,13 +8372,15 @@
 
 	if (!ch->need_queue_hangup) {
 		cb_log(2, port, " --> No need to queue hangup\n");
+		return;
 	}
 
 	ch->need_queue_hangup = 0;
 	if (ch->ast) {
-		send_cause2ast(ch->ast, bc, ch);
-		ast_queue_hangup_with_cause(ch->ast, bc->cause);
-		cb_log(2, port, " --> queue_hangup\n");
+		if (send_cause2ast(ch->ast, bc, ch)) {
+			ast_queue_hangup_with_cause(ch->ast, bc->cause);
+			cb_log(2, port, " --> queue_hangup\n");
+		}
 	} else {
 		cb_log(1, port, "Cannot hangup chan, no ast\n");
 	}
@@ -8653,26 +8654,31 @@
 	}
 }
 
+/*!
+ * \retval -1 if can hangup after calling.
+ * \retval 0 if cannot hangup after calling.
+ */
+static int send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch)
+{
+	int can_hangup;
 
-
-static void send_cause2ast(struct ast_channel *ast, struct misdn_bchannel *bc, struct chan_list *ch) {
 	if (!ast) {
 		chan_misdn_log(1, 0, "send_cause2ast: No Ast\n");
-		return;
+		return 0;
 	}
 	if (!bc) {
 		chan_misdn_log(1, 0, "send_cause2ast: No BC\n");
-		return;
+		return 0;
 	}
 	if (!ch) {
 		chan_misdn_log(1, 0, "send_cause2ast: No Ch\n");
-		return;
+		return 0;
 	}
 
 	ast->hangupcause = bc->cause;
 
+	can_hangup = -1;
 	switch (bc->cause) {
-
 	case AST_CAUSE_UNALLOCATED:
 	case AST_CAUSE_NO_ROUTE_TRANSIT_NET:
 	case AST_CAUSE_NO_ROUTE_DESTINATION:
@@ -8699,15 +8705,16 @@
 			chan_misdn_log(1, bc ? bc->port : 0, "Queued busy already\n");
 			break;
 		}
+		ch->need_busy = 0;
 
 		chan_misdn_log(1, bc ? bc->port : 0, " --> * SEND: Queue Busy pid:%d\n", bc ? bc->pid : -1);
-
 		ast_queue_control(ast, AST_CONTROL_BUSY);
 
-		ch->need_busy = 0;
-
+		/* The BUSY is likely to cause a hangup or the user needs to hear it. */
+		can_hangup = 0;
 		break;
 	}
+	return can_hangup;
 }