Hi Lucas! Am 20.05.2011 22:39, schrieb Lucas Alvarez: You should describe what you want to achieve. Should the registration be done on Kamailio, on Asterisk or both? Anyway, it is just about forwarding a request to another destination. If Kamailio needs to send via UDP, you also have to configure at least one listen=udp:.... address. Otherwise Kamailio can not use UDP transport. You can use port 5060 or any other port. I would deny UDP registrations to Kamailio using 2 different approaches: 1. Firewalling: Use a firewall or local iptables rules to prevent UDP between the clients and Kamailio's UDP listening port. 2. Additionally check transport in kamailio.cfg and reject requests if transport is not TLS (as a "backup" if the firewalling fails), e.g: if(proto!=TLS) { sl_send_reply("403","Use TLS as transport!"); exit; }; regards klaus