Something fishy is going on with my routing. If my SIP UA (91.XXX.XXX.80) hangs up before the receiving end (pstn on 212.YYY.YYY.84) answers, it keeps ringing forever. Below is my routing in regards to CANCEL and the ngrep output. If I understand things correctly, I should send a 487 Request Terminated back to the initiating UA (sip), and I would get a 487 Request Terminated from the pstn provider. I'm not sending the 487 to the UA, and I'm guessing I close the session before my pstn provider sends one to me, so I don't see it with ngrep? The big question is ofcourse what I need to do to get on track, sending the appropriate 487? route: -- #CANCEL processing if (is_method("CANCEL") || is_method("ACK")) { if (t_check_trans()) { setflag(1); if(!t_relay()) { sl_reply_error(); } } exit; }; ngrep output, comments starting with #: -- U 91.XXX.XXX.80:5060 -> 91.ZZZ.ZZZ.9:5060 CANCEL sip:6--------@91.ZZZ.ZZZ.9 SIP/2.0 Via: SIP/2.0/UDP 91.XXX.XXX.80:5060;branch=z9hG4bK1e22091bbd2d0a9b9e0f8de6553d2c27 From: "349--------"<sip:user1@91.ZZZ.ZZZ.9>;tag=XG6525p2-b915854d-1373157639 To: <sip:6--------@91.ZZZ.ZZZ.9> Call -ID: 6C8F-F261-374702698-E353C7B05C17-0006(a)91.XXX.XXX.80 CSeq: 10 CANCEL Max-Forwards: 70 User-Agent: XAVi/XG6525p2-1.6.7 Content-Length: 0 U 91.ZZZ.ZZZ.9:5060 -> 91.XXX.XXX.80:5060 SIP/2.0 200 canceling Via: SIP/2.0/UDP 91.XXX.XXX.80:5060;branch=z9hG4bK1e22091bbd2d0a9b9e0f8de6553d2c27 From: "349--------"<sip:user1@91.ZZZ.ZZZ.9>;tag=XG6525p2-b915854d-1373157639 To: <sip:6--------@91.ZZZ.ZZZ.9>;tag=bbd8f31c58bc6a3266ec5509a254d55b-cb96 Call-ID: 6C8F-F261-374702698-E353C7B05C17-0006(a)91.XXX.XXX.80 CSeq: 10 CANCEL Server: Kamailio (1.4.1-notls (i386/linux)) Content-Length: 0 # 487 Request Terminated from 91.ZZZ.ZZZ.9 to 91.XXX.XXX.80 ?? U 91.ZZZ.ZZZ.9:5060 -> 212.YYY.YYY.84:5060 CANCEL sip:346--------@212.YYY.YYY.84 SIP/2.0 Via: SIP/2.0/UDP 91.ZZZ.ZZZ.9;branch=z9hG4bKe214.208c19e6.0 From: "349--------"<sip:user1@91.ZZZ.ZZZ.9>;tag=XG6525p2-b915854d-1373157639 Call-ID: 6C8F-F261-374702698-E353C7B05C17-0006(a)91.XXX.XXX.80 To: <sip:6--------@91.ZZZ.ZZZ.9> CSeq: 10 CANCEL Max-Forwards: 70 User-Agent: Kamailio (1.4.1-notls (i386/linux)) Content-Length: 0 U 212.YYY.YYY.84:5060 -> 91.ZZZ.ZZZ.9:5060 SIP/2.0 200 OK Via: SIP/2.0/UDP 91.ZZZ.ZZZ.9:5060;branch=z9hG4bKe214.208c19e6.0 To: <sip:6--------@91.ZZZ.ZZZ.9>;tag=a439d513 From: "349--------" <sip:user1@91.ZZZ.ZZZ.9>;tag=XG6525p2-b915854d-1373157639 Call-ID: 6C8F-F261-374702698-E353C7B05C17-0006(a)91.XXX.XXX.80 CSeq: 10 CANCEL User-Agent: ENS2.2.122-IS2 Content-Length: 0 # 487 Request Terminated from 212.YYY.YYY.84 to 91.ZZZ.ZZZ.9 ?? Best Regards, Magnus