Index: channels/chan_iax2.c
===================================================================
--- channels/chan_iax2.c	(revision 168604)
+++ channels/chan_iax2.c	(working copy)
@@ -1122,13 +1122,20 @@
 #define schedule_action(func, data) __schedule_action(func, data, __PRETTY_FUNCTION__)
 #endif
 
-static int iax2_sched_replace(int id, struct sched_context *con, int when, ast_sched_cb callback, const void *data)
+static int _iax2_sched_replace(int *id, struct sched_context *con, int when, ast_sched_cb callback, const void *data, const char *func, int line)
 {
-	AST_SCHED_REPLACE(id, con, when, callback, data);
+	int _count = 0;
+	while (*id > -1 && ast_sched_del(sched, *id) && ++_count < 10) {
+		usleep(1);
+	}
+	if (_count == 10)
+		ast_log(LOG_WARNING, "Unable to cancel schedule ID %d.  This is probably a bug (%s: %s, line %d).\n", *id, __FILE__, func, line);
+	*id = ast_sched_add_variable(sched, when, callback, data, 0);
 	signal_condition(&sched_lock, &sched_cond);
 
-	return id;
+	return *id;
 }
+#define iax2_sched_replace(a,b,c,d,e)	_iax2_sched_replace(&(a),b,c,d,e,__PRETTY_FUNCTION__,__LINE__)
 
 static int iax2_sched_add(struct sched_context *con, int when, ast_sched_cb callback, const void *data)
 {
@@ -4760,7 +4767,7 @@
 	frb.fr2.afdatalen = sizeof(frb.buffer);
 
 	if (!pvt) {
-		ast_log(LOG_WARNING, "No private structure for packet?\n");
+		ast_log(LOG_WARNING, "No private structure for packet? (frametype %d/subtype %d)\n", f->frametype, f->subclass);
 		return -1;
 	}
 	
@@ -5769,9 +5776,10 @@
 				res = 0;
 			else if (!ast_test_flag(&iaxs[callno]->state, IAX_STATE_STARTED))
 				res = 0;
-			else
+			else {
 			/* Simple, just queue for transmission */
 				res = iax2_send(iaxs[callno], f, 0, -1, 0, 0, 0);
+			}
 		} else {
 			ast_debug(1, "Write error: %s\n", strerror(errno));
 		}
@@ -5804,7 +5812,12 @@
 {
 	int res;
 	ast_mutex_lock(&iaxsl[callno]);
-	res = send_command(iaxs[callno], type, command, ts, data, datalen, seqno);
+	if (!iaxs[callno]) {
+		ast_log(LOG_WARNING, "Call %d no longer exists.  Cannot send (type %hhd/cmd %d/ts %u)\n", callno, type, command, ts);
+		res = -1;
+	} else {
+		res = send_command(iaxs[callno], type, command, ts, data, datalen, seqno);
+	}
 	ast_mutex_unlock(&iaxsl[callno]);
 	return res;
 }