U 2013/11/22 08:56:58.606648 2.2.2.2:5060 -> 1.1.1.1:5068 SIP/2.0 183 Progress. Via: SIP/2.0/UDP 1.1.1.1:5068;branch=z9hG4bK8b6b.d794d636.0. Via: SIP/2.0/UDP 192.168.18.150:41314;rport=43238;received=3.3.3.3;branch=z9hG4bK-d8754z-37977264babb1a1c-1---d8754z-. Record-Route: . Record-Route: . Record-Route: . From: ;tag=9b44a312. To: ;tag=8maN3eG8u*ECE8XhvLvxAhPEyZHydAAq. Call-ID: YWZlNGYwMTcwNmMxZjE3MGYwNGUxNGQ3NzY4MTEwZTU.. CSeq: 2 INVITE. Contact: . Server: TS-v4.6.0-09d. Content-Length: 0. 2.2.2.2 - UAC2 1.1.1.1 - Opensips 3.3.3.3 - NAT ******** Opensips.cfg *************** modparam("usrloc", "nat_bflag", 10) Route [2] { … if ($Rp=="5068") { if (nat_uac_test("55")) { fix_nated_contact(); setflag(21); } } … } onreply_route[1] { …. if (isbflagset(10) || (isflagset(21) && nat_uac_test("55"))) fix_nated_contact(); …. }