[Kamailio-Users] Kamailio 1.5.0 and NAT

Hello everybody I have such problem with kamailio and client which behind NAT This is REGISTER message which came from client. This message came from public IP (for example, 1.1.1.1) and source port 44197. (This information I got from sip_trace) REGISTER sip:sip.ptl.ru:5060;transport=UDP SIP/2.0 From: <sip:xxxxxxx@sip.ptl.ru:5060>;tag=a82eda3-13c4-47798948-1a1296-5259a46 To: <sip:xxxxxxx@sip.ptl.ru:5060> Call-ID: a82eda3-13c4-47798948-1a1296-9641c88(a)sip.ptl.ru CSeq: 446229198 REGISTER Via: SIP/2.0/UDP 10.130.237.163:5060;branch=z9hG4bK-47799e27-6b9841-84448db Max-Forwards: 70 Supported: timer Contact: <sip:xxxxxxx@10.130.237.163:5060;transport=UDP> Expires: 60 Content-Length: 0 This is Unauthorized message was sent by kamailio to 1.1.1.1 and: destination port not 44197 (as I expected) but 5060!!! SIP/2.0 401 Unauthorized From: <sip:xxxxxxx@sip.ptl.ru:5060>;tag=a82eda3-13c4-47798948-1a1296-5259a46 To: <sip:xxxxxxx@sip.ptl.ru:5060>;tag=fdc454a3cdd8f9e5718382b74f33aeed.3b81 Call-ID: a82eda3-13c4-47798948-1a1296-9641c88(a)sip.ptl.ru CSeq: 446229198 REGISTER Via: SIP/2.0/UDP 10.130.237.163:5060;branch=z9hG4bK-47799e27-6b9841-84448db;received=1.1.1.1 WWW-Authenticate: Digest realm="domain name", nonce="4af0129b000000047c1020258f9f0efc4de1b76663dd2ab4" Server: Kamailio (1.5.0-notls (i386/linux)) Content-Length: 0 And as you understand 401 reply, which was sent to 1.1.1.1:5060 can't reach client's equipment. A piece of kamailio.cfg relating to REGISTER processing: route(0) { :. if (!is_method("INVITE")) route(8); :. if (is_method("REGISTER")) { route(11); exit; } :.. } route(8) { if (nat_uac_test("5")) { if (method=="REGISTER") { fix_nated_register(); } else { fix_nated_contact(); } setflag(5); } return; } route(11) { if (!www_authorize("", "subscriber")) { www_challenge("", "0"); exit; } if ($au!=$tU) { sl_send_reply("403","Forbidden auth ID"); exit; } if (isflagset(5)) setbflag(6); if (!save("location")) { sl_reply_error(); exit; } } Hearty thanks for any help.