diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index f2cb1395b8601d9528d78f30556e8d4c9201a5f1..60e52370fb7ad61dd888d3105d5614d5b62b069f 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -644,7 +644,7 @@ struct chan_iax2_pvt {
  * on module unload.  This is because all active calls are destroyed, and
  * all frames in this queue will get destroyed as a part of that process.
  */
-static AST_LIST_HEAD_STATIC(frame_queue, iax_frame);
+static AST_LIST_HEAD(, iax_frame) frame_queue[IAX_MAX_CALLS];
 
 /*!
  * This module will get much higher performance when doing a lot of
@@ -2125,13 +2125,12 @@ retry:
 			ast_queue_hangup(owner);
 		}
 
-		AST_LIST_LOCK(&frame_queue);
-		AST_LIST_TRAVERSE(&frame_queue, cur, list) {
+		AST_LIST_LOCK(&frame_queue[pvt->callno]);
+		AST_LIST_TRAVERSE(&frame_queue[pvt->callno], cur, list) {
 			/* Cancel any pending transmissions */
-			if (cur->callno == pvt->callno) 
-				cur->retries = -1;
+			cur->retries = -1;
 		}
-		AST_LIST_UNLOCK(&frame_queue);
+		AST_LIST_UNLOCK(&frame_queue[pvt->callno]);
 
 		if (pvt->reg)
 			pvt->reg->callno = 0;
@@ -2241,9 +2240,12 @@ static void __attempt_transmit(const void *data)
 	/* Do not try again */
 	if (freeme) {
 		/* Don't attempt delivery, just remove it from the queue */
-		AST_LIST_LOCK(&frame_queue);
-		AST_LIST_REMOVE(&frame_queue, f, list);
-		AST_LIST_UNLOCK(&frame_queue);
+		if (callno) {
+			/* XXX Note that there should never be a frame without a callno ... */
+			AST_LIST_LOCK(&frame_queue[callno]);
+			AST_LIST_REMOVE(&frame_queue[callno], f, list);
+			AST_LIST_UNLOCK(&frame_queue[callno]);
+		}
 		f->retrans = -1;
 		/* Free the IAX frame */
 		iax2_frame_free(f);
@@ -2507,7 +2509,7 @@ static char *complete_iax2_show_peer(const char *line, const char *word, int pos
 static char *handle_cli_iax2_show_stats(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
 {
 	struct iax_frame *cur;
-	int cnt = 0, dead = 0, final = 0;
+	int cnt = 0, dead = 0, final = 0, i;
 
 	switch (cmd) {
 	case CLI_INIT:
@@ -2523,15 +2525,17 @@ static char *handle_cli_iax2_show_stats(struct ast_cli_entry *e, int cmd, struct
 	if (a->argc != 3)
 		return CLI_SHOWUSAGE;
 
-	AST_LIST_LOCK(&frame_queue);
-	AST_LIST_TRAVERSE(&frame_queue, cur, list) {
-		if (cur->retries < 0)
-			dead++;
-		if (cur->final)
-			final++;
-		cnt++;
+	for (i = 0; i < IAX_MAX_CALLS; i++) {
+		AST_LIST_LOCK(&frame_queue[i]);
+		AST_LIST_TRAVERSE(&frame_queue[i], cur, list) {
+			if (cur->retries < 0)
+				dead++;
+			if (cur->final)
+				final++;
+			cnt++;
+		}
+		AST_LIST_UNLOCK(&frame_queue[i]);
 	}
-	AST_LIST_UNLOCK(&frame_queue);
 
 	ast_cli(a->fd, "    IAX Statistics\n");
 	ast_cli(a->fd, "---------------------\n");
@@ -2884,9 +2888,9 @@ static int iax2_transmit(struct iax_frame *fr)
 	/* By setting this to 0, the network thread will send it for us, and
 	   queue retransmission if necessary */
 	fr->sentyet = 0;
-	AST_LIST_LOCK(&frame_queue);
-	AST_LIST_INSERT_TAIL(&frame_queue, fr, list);
-	AST_LIST_UNLOCK(&frame_queue);
+	AST_LIST_LOCK(&frame_queue[fr->callno]);
+	AST_LIST_INSERT_TAIL(&frame_queue[fr->callno], fr, list);
+	AST_LIST_UNLOCK(&frame_queue[fr->callno]);
 	/* Wake up the network and scheduler thread */
 	if (netthreadid != AST_PTHREADT_NULL)
 		pthread_kill(netthreadid, SIGURG);
@@ -6223,15 +6227,14 @@ static int complete_transfer(int callno, struct iax_ies *ies)
 	pvt->lastsent = 0;
 	pvt->nextpred = 0;
 	pvt->pingtime = DEFAULT_RETRY_TIME;
-	AST_LIST_LOCK(&frame_queue);
-	AST_LIST_TRAVERSE(&frame_queue, cur, list) {
+	AST_LIST_LOCK(&frame_queue[callno]);
+	AST_LIST_TRAVERSE(&frame_queue[callno], cur, list) {
 		/* We must cancel any packets that would have been transmitted
 		   because now we're talking to someone new.  It's okay, they
 		   were transmitted to someone that didn't care anyway. */
-		if (callno == cur->callno) 
-			cur->retries = -1;
+		cur->retries = -1;
 	}
-	AST_LIST_UNLOCK(&frame_queue);
+	AST_LIST_UNLOCK(&frame_queue[callno]);
 	return 0; 
 }
 
@@ -6828,8 +6831,8 @@ static void vnak_retransmit(int callno, int last)
 {
 	struct iax_frame *f;
 
-	AST_LIST_LOCK(&frame_queue);
-	AST_LIST_TRAVERSE(&frame_queue, f, list) {
+	AST_LIST_LOCK(&frame_queue[callno]);
+	AST_LIST_TRAVERSE(&frame_queue[callno], f, list) {
 		/* Send a copy immediately */
 		if ((f->callno == callno) && iaxs[f->callno] &&
 			((unsigned char ) (f->oseqno - last) < 128) &&
@@ -6837,7 +6840,7 @@ static void vnak_retransmit(int callno, int last)
 			send_packet(f);
 		}
 	}
-	AST_LIST_UNLOCK(&frame_queue);
+	AST_LIST_UNLOCK(&frame_queue[callno]);
 }
 
 static void __iax2_poke_peer_s(const void *data)
@@ -7775,17 +7778,17 @@ static int socket_process(struct iax2_thread *thread)
 					if (iaxdebug)
 						ast_debug(1, "Cancelling transmission of packet %d\n", x);
 					call_to_destroy = 0;
-					AST_LIST_LOCK(&frame_queue);
-					AST_LIST_TRAVERSE(&frame_queue, cur, list) {
+					AST_LIST_LOCK(&frame_queue[fr->callno]);
+					AST_LIST_TRAVERSE(&frame_queue[fr->callno], cur, list) {
 						/* If it's our call, and our timestamp, mark -1 retries */
-						if ((fr->callno == cur->callno) && (x == cur->oseqno)) {
+						if (x == cur->oseqno) {
 							cur->retries = -1;
 							/* Destroy call if this is the end */
 							if (cur->final)
 								call_to_destroy = fr->callno;
 						}
 					}
-					AST_LIST_UNLOCK(&frame_queue);
+					AST_LIST_UNLOCK(&frame_queue[fr->callno]);
 					if (call_to_destroy) {
 						if (iaxdebug)
 							ast_debug(1, "Really destroying %d, having been acked on final message\n", call_to_destroy);
@@ -7995,13 +7998,13 @@ retryowner:
 			case IAX_COMMAND_TXACC:
 				if (iaxs[fr->callno]->transferring == TRANSFER_BEGIN) {
 					/* Ack the packet with the given timestamp */
-					AST_LIST_LOCK(&frame_queue);
-					AST_LIST_TRAVERSE(&frame_queue, cur, list) {
+					AST_LIST_LOCK(&frame_queue[fr->callno]);
+					AST_LIST_TRAVERSE(&frame_queue[fr->callno], cur, list) {
 						/* Cancel any outstanding txcnt's */
-						if ((fr->callno == cur->callno) && (cur->transfer))
+						if (cur->transfer)
 							cur->retries = -1;
 					}
-					AST_LIST_UNLOCK(&frame_queue);
+					AST_LIST_UNLOCK(&frame_queue[fr->callno]);
 					memset(&ied1, 0, sizeof(ied1));
 					iax_ie_append_short(&ied1, IAX_IE_CALLNO, iaxs[fr->callno]->callno);
 					send_command(iaxs[fr->callno], AST_FRAME_IAX, IAX_COMMAND_TXREADY, 0, ied1.buf, ied1.pos, -1);
@@ -8868,13 +8871,13 @@ retryowner2:
 				break;	
 			case IAX_COMMAND_TXMEDIA:
 				if (iaxs[fr->callno]->transferring == TRANSFER_READY) {
-					AST_LIST_LOCK(&frame_queue);
-					AST_LIST_TRAVERSE(&frame_queue, cur, list) {
+					AST_LIST_LOCK(&frame_queue[fr->callno]);
+					AST_LIST_TRAVERSE(&frame_queue[fr->callno], cur, list) {
 						/* Cancel any outstanding frames and start anew */
-						if ((fr->callno == cur->callno) && (cur->transfer))
+						if (cur->transfer)
 							cur->retries = -1;
 					}
-					AST_LIST_UNLOCK(&frame_queue);
+					AST_LIST_UNLOCK(&frame_queue[fr->callno]);
 					/* Start sending our media to the transfer address, but otherwise leave the call as-is */
 					iaxs[fr->callno]->transferring = TRANSFER_MEDIAPASS;
 				}
@@ -9551,25 +9554,17 @@ static void *sched_thread(void *ignore)
 	return NULL;
 }
 
-static void *network_thread(void *ignore)
+static int transmit_queued_frames(void)
 {
-	/* Our job is simple: Send queued messages, retrying if necessary.  Read frames 
-	   from the network, and queue them for delivery to the channels */
-	int res, count, wakeup;
+	int wakeup = -1, count = 0, i;
 	struct iax_frame *f;
 
-	if (timingfd > -1)
-		ast_io_add(io, timingfd, timing_read, AST_IO_IN | AST_IO_PRI, NULL);
-	
-	for(;;) {
-		pthread_testcancel();
-
-		/* Go through the queue, sending messages which have not yet been
-		   sent, and scheduling retransmissions if appropriate */
-		AST_LIST_LOCK(&frame_queue);
-		count = 0;
-		wakeup = -1;
-		AST_LIST_TRAVERSE_SAFE_BEGIN(&frame_queue, f, list) {
+	for (i = 0; i < IAX_MAX_CALLS; i++) {
+		/* As an optimization, only lock this frame queue if it is non-empty. */
+		if (AST_LIST_EMPTY(&frame_queue[i]))
+			continue;
+		AST_LIST_LOCK(&frame_queue[i]);
+		AST_LIST_TRAVERSE_SAFE_BEGIN(&frame_queue[i], f, list) {
 			if (f->sentyet)
 				continue;
 			
@@ -9578,16 +9573,16 @@ static void *network_thread(void *ignore)
 				wakeup = 1;
 				continue;
 			}
-
+	
 			f->sentyet = 1;
-
+	
 			if (iaxs[f->callno]) {
 				send_packet(f);
 				count++;
 			} 
-
+	
 			ast_mutex_unlock(&iaxsl[f->callno]);
-
+	
 			if (f->retries < 0) {
 				/* This is not supposed to be retransmitted */
 				AST_LIST_REMOVE_CURRENT(list);
@@ -9600,11 +9595,33 @@ static void *network_thread(void *ignore)
 			}
 		}
 		AST_LIST_TRAVERSE_SAFE_END;
-		AST_LIST_UNLOCK(&frame_queue);
+		AST_LIST_UNLOCK(&frame_queue[i]);
+	}
+
+	if (count >= 20)
+		ast_debug(1, "chan_iax2: Sent %d queued outbound frames all at once\n", count);
+
+	return wakeup;
+}
+
+
+static void *network_thread(void *ignore)
+{
+	/* Our job is simple: Send queued messages, retrying if necessary.  Read frames 
+	   from the network, and queue them for delivery to the channels */
+	int res, wakeup;
+
+	if (timingfd > -1)
+		ast_io_add(io, timingfd, timing_read, AST_IO_IN | AST_IO_PRI, NULL);
+	
+	for(;;) {
+		pthread_testcancel();
+
+		/* Go through the queue, sending messages which have not yet been
+		   sent, and scheduling retransmissions if appropriate */
+		wakeup = transmit_queued_frames();
 
 		pthread_testcancel();
-		if (count >= 20)
-			ast_debug(1, "chan_iax2: Sent %d queued outbound frames all at once\n", count);
 
 		/* Now do the IO, and run scheduled tasks */
 		res = ast_io_wait(io, wakeup);
@@ -11455,12 +11472,10 @@ static int __unload_module(void)
 	/* Grab the sched lock resource to keep it away from threads about to die */
 	/* Cancel the network thread, close the net socket */
 	if (netthreadid != AST_PTHREADT_NULL) {
-		AST_LIST_LOCK(&frame_queue);
 		ast_mutex_lock(&sched_lock);
 		pthread_cancel(netthreadid);
 		ast_cond_signal(&sched_cond);
 		ast_mutex_unlock(&sched_lock);	/* Release the schedule lock resource */
-		AST_LIST_UNLOCK(&frame_queue);
 		pthread_join(netthreadid, NULL);
 	}
 	if (schedthreadid != AST_PTHREADT_NULL) {
@@ -11509,8 +11524,10 @@ static int __unload_module(void)
 	sched_context_destroy(sched);
 	reload_firmware(1);
 
-	for (x = 0; x < IAX_MAX_CALLS; x++)
+	for (x = 0; x < IAX_MAX_CALLS; x++) {
 		ast_mutex_destroy(&iaxsl[x]);
+		AST_LIST_HEAD_DESTROY(&frame_queue[x]);
+	}
 
 	ao2_ref(peers, -1);
 	ao2_ref(users, -1);
@@ -11574,8 +11591,10 @@ static int load_module(void)
 
 	memset(iaxs, 0, sizeof(iaxs));
 
-	for (x=0;x<IAX_MAX_CALLS;x++)
+	for (x = 0; x < IAX_MAX_CALLS; x++) {
 		ast_mutex_init(&iaxsl[x]);
+		AST_LIST_HEAD_INIT(&frame_queue[x]);
+	}
 
 	ast_cond_init(&sched_cond, NULL);