--- channels/chan_sip.c.orig	2007-08-20 11:07:46.695095949 +0200
+++ channels/chan_sip.c	2007-08-21 15:13:51.000000000 +0200
@@ -4872,6 +4872,7 @@
 	int vpeercapability = 0, vpeernoncodeccapability = 0;
 	struct sockaddr_in sin;		/*!< media socket address */
 	struct sockaddr_in vsin;	/*!< Video socket address */
+	struct sockaddr_in rsin;	/*!< RTP socket address */
 
 	const char *codecs;
 	struct hostent *hp;		/*!< RTP Audio host IP */
@@ -5032,7 +5033,9 @@
 	/* RTP addresses and ports for audio and video */
 	sin.sin_family = AF_INET;
 	vsin.sin_family = AF_INET;
+	rsin.sin_family = AF_INET;
 	memcpy(&sin.sin_addr, hp->h_addr, sizeof(sin.sin_addr));
+	memcpy(&rsin.sin_addr, hp->h_addr, sizeof(rsin.sin_addr));
 	if (vhp)
 		memcpy(&vsin.sin_addr, vhp->h_addr, sizeof(vsin.sin_addr));
 
@@ -5040,6 +5043,20 @@
 	if (p->udptl) {
 		if (udptlportno > 0) {
 			sin.sin_port = htons(udptlportno);
+
+			if ((ast_test_flag(&p->flags[0], SIP_NAT)) == SIP_NAT) {
+				ast_rtp_get_peer(p->rtp, &rsin);
+				if (strcasecmp(ast_inet_ntoa(rsin.sin_addr), "0.0.0.0") != 0) {
+					sin.sin_addr = rsin.sin_addr;
+					if (debug)
+						ast_log(LOG_DEBUG,"Peer T.38 UDPTL is behind NAT, using RTP port %s:%d\n", ast_inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));
+				} else {
+					sin.sin_addr = p->recv.sin_addr;
+					if (debug)
+						ast_log(LOG_DEBUG,"Peer T.38 UDPTL is behind NAT, using SIP port %s:%d\n", ast_inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));
+				}
+			}
+
 			ast_udptl_set_peer(p->udptl, &sin);
 			if (debug)
 				ast_log(LOG_DEBUG,"Peer T.38 UDPTL is at port %s:%d\n",ast_inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));