--- asterisk-1.4.23/channels/chan_sip.c	2009-01-13 19:34:14.000000000 +0100
+++ asterisk-1.4.23-patched/channels/chan_sip.c	2009-02-06 10:46:52.000000000 +0100
@@ -2912,7 +2914,7 @@
 	struct ast_hostent ahp;
 	struct sip_peer *p;
 	char *port;
-	int portno;
+	int portno=0;
 	char host[MAXHOSTNAMELEN], *hostn;
 	char peer[256];
 
@@ -2934,8 +2936,8 @@
 		return res;
 	}
 	hostn = peer;
-	portno = port ? atoi(port) : STANDARD_SIP_PORT;
-	if (srvlookup) {
+	/* if the URI contains a port we must not perform an SRV lookup */
+	if (!port && srvlookup) {
 		char service[MAXHOSTNAMELEN];
 		int tportno;
 		int ret;
@@ -2946,7 +2948,10 @@
 			hostn = host;
 			portno = tportno;
 		}
-	}
+	}
+	if (!portno)
+		portno = port ? atoi(port) : STANDARD_SIP_PORT;
+
 	hp = ast_gethostbyname(hostn, &ahp);
 	if (!hp) {
 		ast_log(LOG_WARNING, "No such host: %s\n", peer);