First, you should not do user location lookup for REGISTER requests since the r-uri in these requests contains only proxy address. Then, instead of next statement: if (!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; use if (!lookup("location")) { t_relay_to_udp("proxy_address", "proxy_port"); break; }; in your config file. You should take care to avoid creating loops between proxies. You can use forward_udp(...) instead of t_relay_to_udp(...) if you want stateless forwarding. Daniel On 12/13/04 09:10, szj wrote: