When canceling the call, asterisk sends Asterisk => Phone U 192.168.10.72:25060 -> 192.168.10.72:5060 CANCEL sip:arthur@192.168.10.72 SIP/2.0. Via: SIP/2.0/UDP 192.168.10.72:25060;branch=z9hG4bK51b7d580. Max-Forwards: 70. From: "Max M..ller" ;tag=as20b6fbd0. To: . Call-ID: 678528c72ee8d5b92c097db80d098f23@192.168.10.72. CSeq: 102 CANCEL. Proxy => Asterisk U 192.168.10.72:5060 -> 192.168.10.72:25060 SIP/2.0 200 canceling. Via: SIP/2.0/UDP 192.168.10.72:25060;branch=z9hG4bK51b7d580. From: "Max M..ller" ;tag=as20b6fbd0. To: ;tag=5a0ebe5a1e244b13451a7193622b8c72-eaee. Call-ID: 678528c72ee8d5b92c097db80d098f23@192.168.10.72. CSeq: 102 CANCEL. Proxy => Phone U 192.168.10.72:5060 -> 192.168.10.221:58353 CANCEL sip:arthur@192.168.10.221:58353;line=qs8ttziy SIP/2.0. Via: SIP/2.0/UDP 192.168.10.72;branch=z9hG4bKafc1.8258f907.0. From: "Max M..ller" ;tag=as20b6fbd0. Call-ID: 678528c72ee8d5b92c097db80d098f23@192.168.10.72. To: . CSeq: 102 CANCEL.