etc/kamailio.cfg: use flag 'r' for rtpproxy if ip in sdp is not private

- skip learning mode, advertised media ip is routable

etc/kamailio.cfg

@@ -784,7 +784,11 @@ route[NATMANAGE] {
 	if (!(isflagset(FLT_NATS) || isbflagset(FLB_NATB)))
 		return;
 
-	rtpproxy_manage("co");
+	if(nat_uac_test("8")) {
+		rtpproxy_manage("co");
+	} else {
+		rtpproxy_manage("cor");
+	}
 
 	if (is_request()) {
 		if (!has_totag()) {