sip: Actually honor the remote port of the pbx

So far the remote_port has never been used. sofia-sip did the right
thing and put the port into the "Contact" and the rport option for
the via. But we would have never been able to connect a PBX on a
different port (as sofia-sip seems to parse the destination from the
to address).

Change-Id: Ifbd49b4aa6b01b118fe67e39dddef50b2946159c

src/sip.c

@@ -293,12 +293,14 @@ static int send_invite(struct sip_agent *agent, struct sip_call_leg *leg,
 {
 	struct call_leg *other = leg->base.call->initial;
 
-	char *from = talloc_asprintf(leg, "sip:%s@%s",
+	char *from = talloc_asprintf(leg, "sip:%s@%s:%d",
 				calling_num,
-				agent->app->sip.local_addr);
-	char *to = talloc_asprintf(leg, "sip:%s@%s",
+				agent->app->sip.local_addr,
+				agent->app->sip.local_port);
+	char *to = talloc_asprintf(leg, "sip:%s@%s:%d",
 				called_num,
-				agent->app->sip.remote_addr);
+				agent->app->sip.remote_addr,
+				agent->app->sip.remote_port);
 	char *sdp = sdp_create_file(leg, other);
 
 	leg->state = SIP_CC_INITIAL;