diff -ur asterisk-1.0.3.bak/channel.c asterisk/channel.c
--- asterisk-1.0.3.bak/channel.c	2004-12-15 17:45:21.000000000 -0500
+++ asterisk/channel.c	2004-12-15 17:51:26.000000000 -0500
@@ -373,13 +373,27 @@
 	struct ast_frame *prev, *cur;
 	int blah = 1;
 	int qlen = 0;
+	int retries = 0;
+	
 	/* Build us a copy and free the original one */
 	f = ast_frdup(fin);
 	if (!f) {
 		ast_log(LOG_WARNING, "Unable to duplicate frame\n");
 		return -1;
 	}
-	ast_mutex_lock(&chan->lock);
+
+retry:
+        if (ast_mutex_trylock(&chan->lock)) {
+        	if (retries < 100) {
+                	usleep(1);
+                        retries++;
+                        goto retry;
+                } else {
+               	 	ast_log(LOG_WARNING, "Avoided deadlock on channel %s, %d retries",chan->name,retries);
+               	 	return -1;
+		}
+	}
+
 	prev = NULL;
 	cur = chan->pvt->readq;
 	while(cur) {
diff -ur asterisk-1.0.3.bak/channels/chan_h323.c asterisk/channels/chan_h323.c
--- asterisk-1.0.3.bak/channels/chan_h323.c	2004-12-15 17:45:21.000000000 -0500
+++ asterisk/channels/chan_h323.c	2004-12-15 17:51:48.000000000 -0500
@@ -580,6 +580,12 @@
 	/* Retrieve audio/etc from channel.  Assumes p->lock is already held. */
 	struct ast_frame *f;
 	static struct ast_frame null_frame = { AST_FRAME_NULL, };
+	static struct ast_frame hangup_frame = { AST_FRAME_CONTROL, AST_CONTROL_HANGUP };
+
+	if (!p->rtp) {
+		ast_log(LOG_WARNING,"request to read rtp after rtp was destroyed");
+		return &hangup_frame;
+        }
 
       /* Only apply it for the first packet, we just need the correct ip/port */
       if(p->nat)