--- channels/chan_sip.c	(Asterisk 13.38.0)
+++ channels/chan_sip.c	(working copy)
@@ -3796,7 +3796,10 @@ static int __sip_xmit(struct sip_pvt *p,
 static void build_via(struct sip_pvt *p)
 {
 	/* Work around buggy UNIDEN UIP200 firmware */
-	const char *rport = (ast_test_flag(&p->flags[0], SIP_NAT_FORCE_RPORT) || ast_test_flag(&p->flags[0], SIP_NAT_RPORT_PRESENT)) ? ";rport" : "";
+	const char *rport = (p->socket.type == AST_TRANSPORT_UDP &&
+		(ast_test_flag(&p->flags[0], SIP_NAT_FORCE_RPORT) ||
+		 ast_test_flag(&p->flags[0], SIP_NAT_RPORT_PRESENT)))
+		? ";rport" : "";
 
 	/* z9hG4bK is a magic cookie.  See RFC 3261 section 8.1.1.7 */
 	snprintf(p->via, sizeof(p->via), "SIP/2.0/%s %s;branch=z9hG4bK%08x%s",