[Serusers] nathelper question

Hi all, The problem is I can't register two SIP UAs to SER server. This is my environment: Internet | router (X.X.X.163) | |Fiber |---- Ser server (X.X.X.166) | | Switch------|---- Trunk Gateway (X.X.X.167) | |---- Other servers | |---- Router( cisco 26xx) (X.X.X.163) | Switch | _____________________|_________________ Users SIP UA1(172.16.2.11) SIP UA2(172.16.2.23) My ser.cfg like: route{ if ( msg:len > max_len ) { sl_send_reply("513", "Message too big"); break; }; record_route(); if (loose_route()) { t_relay(); break; }; if (!method=="BYE") { force_rport(); fix_nated_contact(); }; if (method=="REGISTER") { if (!www_authorize("novsky.com", "subscriber")) { www_challenge("novsky.com", "1"); break; }; save("location"); break; }; if (method=="INVITE") { if(!proxy_authorize("novsky.com","subscriber")) { proxy_challenge("novsky.com","1"); break; }; }; if(uri=~"^sip:6169[0-9]*@[0-9|\.]*") { if(!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; }else { forward(172.16.255.2,6050); break; }; if (!t_relay()) { sl_reply_error(); }; } I use ethereal to look the packet, first UA1 send REGISTER to SER server, on NAT it use 5060 port, and SER return to corrent address/port. When UA2 send REGISTER to SER server, on NAT it use 1027 port, but SER return to NAT:5060 port and the packet transfered to UA1. So UA2 can't register. I can see the NAT table on route, like udp x.x.x.165:5060 172.16.2.11:5060 x.x.x.165:5060 x.x.x.x.165:5060 udp x.x.x.165:5060 172.16.2.23:5060 x.x.x.165:1025 x.x.x.x.165:1025 Wangji 12/1/03 __________________________________ Do you Yahoo!? Protect your identity with Yahoo! Mail AddressGuard http://antispam.yahoo.com/whatsnewfree