root@comcerto:~# tcpdump -i any port 6060 or port 5060 -v
tcpdump: listening on any, link-type LINUX_SLL (Linux cooked v1), capture size 262144 bytes
07:34:28.410107 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 991)
    192.168.20.97.5060 > 192.168.20.98.5060: SIP, length: 963
        INVITE sip:22@192.168.20.98:5060 SIP/2.0
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK4109705569
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 1 INVITE
        Contact: <sip:11@192.168.20.97:5060>
        Content-Type: application/sdp
        Allow: INVITE, INFO, PRACK, ACK, BYE, CANCEL, OPTIONS, NOTIFY, REGISTER, SUBSCRIBE, REFER, PUBLISH, UPDATE, MESSAGE
        Max-Forwards: 70
        User-Agent: Yealink SIP-T21P_E2 52.82.14.1
        Supported: timer
        Session-Expires: 300;refresher=uac
        Min-SE: 90
        Allow-Events: talk,hold,conference,refer,check-sync
        Supported: replaces
        Content-Length: 308

        v=0
        o=- 20075 20075 IN IP4 192.168.20.97
        s=SDP data
        c=IN IP4 192.168.20.97
        t=0 0
        m=audio 12202 RTP/AVP 9 0 8 18 101
        a=rtpmap:9 G722/8000
        a=rtpmap:0 PCMU/8000
        a=rtpmap:8 PCMA/8000
        a=rtpmap:18 G729/8000
        a=fmtp:18 annexb=no
        a=ptime:20
        a=sendrecv
        a=rtpmap:101 telephone-event/8000
        a=fmtp:101 0-15
07:34:28.422346 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 464)
    192.168.20.98.5060 > 192.168.20.97.5060: SIP, length: 436
        SIP/2.0 407 Proxy Authentication Required
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK4109705569
        Proxy-Authenticate: Digest nonce="1747035268:ea4911901351f68ef492235f690dc9fd",algorithm=MD5,realm="192.168.20.98",qop="auth,auth-int"
        To: <sip:22@192.168.20.98:5060>;tag=e9567636
        From: "11"<sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 1 INVITE
        Server: repro 1.12.0
        Content-Length: 0

07:34:28.428118 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 300)
    192.168.20.97.5060 > 192.168.20.98.5060: SIP, length: 272
        ACK sip:22@192.168.20.98:5060 SIP/2.0
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK4109705569
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>;tag=e9567636
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 1 ACK
        Content-Length: 0

07:34:28.436138 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 1245)
    192.168.20.97.5060 > 192.168.20.98.5060: SIP, length: 1217
        INVITE sip:22@192.168.20.98:5060 SIP/2.0
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Contact: <sip:11@192.168.20.97:5060>
        Proxy-Authorization: Digest username="11", realm="192.168.20.98", nonce="1747035268:ea4911901351f68ef492235f690dc9fd", uri="sip:22@192.168.20.98:5060", response="59d544799589fcd307455f7fffe02b32", algorithm=MD5, cnonce="0a4f113b", qop=auth, nc=00000001
        Content-Type: application/sdp
        Allow: INVITE, INFO, PRACK, ACK, BYE, CANCEL, OPTIONS, NOTIFY, REGISTER, SUBSCRIBE, REFER, PUBLISH, UPDATE, MESSAGE
        Max-Forwards: 70
        User-Agent: Yealink SIP-T21P_E2 52.82.14.1
        Supported: timer
        Session-Expires: 300;refresher=uac
        Min-SE: 90
        Allow-Events: talk,hold,conference,refer,check-sync
        Supported: replaces
        Content-Length: 308

        v=0
        o=- 20075 20075 IN IP4 192.168.20.97
        s=SDP data
        c=IN IP4 192.168.20.97
        t=0 0
        m=audio 12202 RTP/AVP 9 0 8 18 101
        a=rtpmap:9 G722/8000
        a=rtpmap:0 PCMU/8000
        a=rtpmap:8 PCMA/8000
        a=rtpmap:18 G729/8000
        a=fmtp:18 annexb=no
        a=ptime:20
        a=sendrecv
        a=rtpmap:101 telephone-event/8000
        a=fmtp:101 0-15
07:34:28.463367 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 1132)
    localhost..5060 > localhost..6060: SIP, length: 1104
        INVITE sip:22@127.0.0.1:6060;transport=udp SIP/2.0
        Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---c4a4922b9bb6c548;rport
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        Max-Forwards: 69
        Record-Route: <sip:192.168.20.98:5060;transport=udp;lr>
        Contact: <sip:11@192.168.20.97:5060>
        To: <sip:22@192.168.20.98:5060>
        From: "11"<sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Session-Expires: 300;refresher=uac
        Min-SE: 90
        Allow: INVITE, INFO, PRACK, ACK, BYE, CANCEL, OPTIONS, NOTIFY, REGISTER, SUBSCRIBE, REFER, PUBLISH, UPDATE, MESSAGE
        Content-Type: application/sdp
        Supported: timer, replaces
        User-Agent: Yealink SIP-T21P_E2 52.82.14.1
        Allow-Events: talk, hold, conference, refer, check-sync
        Content-Length: 308

        v=0
        o=- 20075 20075 IN IP4 192.168.20.97
        s=SDP data
        c=IN IP4 192.168.20.97
        t=0 0
        m=audio 12202 RTP/AVP 9 0 8 18 101
        a=rtpmap:9 G722/8000
        a=rtpmap:0 PCMU/8000
        a=rtpmap:8 PCMA/8000
        a=rtpmap:18 G729/8000
        a=fmtp:18 annexb=no
        a=ptime:20
        a=sendrecv
        a=rtpmap:101 telephone-event/8000
        a=fmtp:101 0-15
07:34:28.473176 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 384)
    localhost..6060 > localhost..5060: SIP, length: 356
        SIP/2.0 100 Trying
        Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---c4a4922b9bb6c548;rport=5060
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        User-Agent: eXosip/5.3.0
        Content-Length: 0

07:34:28.531688 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 271)
    192.168.20.98.5060 > 192.168.20.97.5060: SIP, length: 243
        SIP/2.0 100 Trying
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        To: <sip:22@192.168.20.98:5060>
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Content-Length: 0

07:34:28.624240 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 865)
    localhost..6060 > localhost..5060: SIP, length: 837
        SIP/2.0 183 Session Progress
        Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---c4a4922b9bb6c548;rport=5060
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        Record-Route: <sip:192.168.20.98:5060;transport=udp;lr>
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Contact: <sip:22@127.0.0.1:6060>
        Content-Type: application/sdp
        Allow: INVITE,ACK,BYE,CANCEL,OPTIONS,REFER,NOTIFY,INFO,UPDATE,PRACK,SUBSCRIBE
        User-Agent: eXosip/5.3.0
        Allow-Events: conference
        Supported: replaces,timer,100rel
        Content-Length:   191

        v=0
        o=gateway 0 0 IN IP4 192.168.20.98
        s=conversation
        c=IN IP4 192.168.20.98
        t=0 0
        m=audio 12000 RTP/AVP 9 101
        a=rtpmap:9 G722/8000
        a=rtpmap:101 telephone-event/8000
        a=fmtp:101 0-15
07:34:28.660905 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 810)
    192.168.20.98.5060 > 192.168.20.97.5060: SIP, length: 782
        SIP/2.0 183 Session Progress
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        Record-Route: <sip:192.168.20.98:5060;transport=udp;lr>
        Contact: <sip:22@127.0.0.1:6060>
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, REFER, NOTIFY, INFO, UPDATE, PRACK, SUBSCRIBE
        Content-Type: application/sdp
        Server: repro 1.12.0
        Supported: replaces, timer, 100rel
        User-Agent: eXosip/5.3.0
        Allow-Events: conference
        Content-Length: 191

        v=0
        o=gateway 0 0 IN IP4 192.168.20.98
        s=conversation
        c=IN IP4 192.168.20.98
        t=0 0
        m=audio 12000 RTP/AVP 9 101
        a=rtpmap:9 G722/8000
        a=rtpmap:101 telephone-event/8000
        a=fmtp:101 0-15
07:34:32.476793 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 541)
    localhost..6060 > localhost..5060: SIP, length: 513
        SIP/2.0 404 Not Found
        Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---c4a4922b9bb6c548;rport=5060
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Allow: INVITE,ACK,BYE,CANCEL,OPTIONS,REFER,NOTIFY,INFO,UPDATE,PRACK,SUBSCRIBE
        User-Agent: eXosip/5.3.0
        Allow-Events: conference
        Supported: replaces,timer,100rel
        Content-Length: 0

07:34:32.487147 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 349)
    localhost..5060 > localhost..6060: SIP, length: 321
        ACK sip:22@127.0.0.1:6060;transport=udp SIP/2.0
        Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---c4a4922b9bb6c548;rport
        Max-Forwards: 70
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        From: "11"<sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 ACK
        Content-Length: 0

07:34:32.490835 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 488)
    192.168.20.98.5060 > 192.168.20.97.5060: SIP, length: 460
        SIP/2.0 404 Not Found
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 INVITE
        Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, REFER, NOTIFY, INFO, UPDATE, PRACK, SUBSCRIBE
        Server: repro 1.12.0
        Supported: replaces, timer, 100rel
        User-Agent: eXosip/5.3.0
        Allow-Events: conference
        Content-Length: 0

07:34:32.498157 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 302)
    192.168.20.97.5060 > 192.168.20.98.5060: SIP, length: 274
        ACK sip:22@192.168.20.98:5060 SIP/2.0
        Via: SIP/2.0/UDP 192.168.20.97:5060;branch=z9hG4bK1154999255
        From: "11" <sip:11@192.168.20.98:5060>;tag=113478370
        To: <sip:22@192.168.20.98:5060>;tag=1286645902
        Call-ID: 0_1141091475@192.168.20.97
        CSeq: 2 ACK
        Content-Length: 0

07:34:34.468160 IP (tos 0x68, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 32)
    192.168.20.97.5060 > 192.168.20.98.5060: SIP

14 packets captured
19 packets received by filter
0 packets dropped by kernel
root@comcerto:~#