Dialog missing when BYE is received from trunk - sr-users

28 Jul 2019

Hi all,

I’ve got a call flow where PBX makes a call via Kamailio, which uses the UAC modules to
make the call to the trunk. This works great, however I’ve noticed recently that when the
BYE comes from the trunk, Kamailio doesn’t recognise the dialog and throws back a 404. Due
to this, the PBX never knows the session has ended, and keeps its session open.

Here’s the flow from Wireshark:

https://i.imgur.com/BxPRrXP.png <https://i.imgur.com/BxPRrXP.png>

As you can see, the BYE is received from the trunk, and Kamailio throws a 404. I checked
with an rpc dlg.list and at this point the dialog had gone. 30 seconds later, I threw a
BYE from the PBX, and because the dialog no longer existed, it got a 481 back.

The INVITE to the trunk has the following Record-Route header:

Record-Route:
<sip:kamailio.public-ip;lr;ftag=mjKtcKaBteQ4Q;vst=AAAAAAYFBQUHAwYHBgRzMwIRGRMcAgJBWBEVCwAbBhtADxBjdGVkLmNvbS5hdQ--;did=624.b2e1>

When the first BYE comes in, it still has same did in the Route header.

Below I’ve put the output from the dialog list rpc call (before the first BYE) and the
relevant log lines. 

{
        h_entry: 1062
        h_id: 7723
        ref: 2
        call-id: a9d32620-2b68-1238-048a-0cc47a18705a
        from_uri: sip:61400123123@pbx.local:5060
        to_uri: sip:61400123123@10.0.0.2
        state: 4
        start_ts: 1564269942
        init_ts: 1564269929
        end_ts: 0
        timeout: 1564313142
        lifetime: 43200
        dflags: 643
        sflags: 0
        iflags: 16
        caller: {
                tag: mjKtcKaBteQ4Q
                contact: sip:pbx.local
                cseq: 7581172
                route_set:
                socket: udp:10.0.0.2:5060
        }
        callee: {
                tag: SD5ptp899-1177933201-1564269931305
                contact:
sip:SDd3mt8-nn9jnirnmqcrvfmvkpm0hmhvgggjgv2io788of70s84u9@trunk.remote:5060;transport=udp
                cseq: 0
                route_set:
                socket: udp:10.0.0.2:5060
        }
        profiles: {
        }
        variables: {
                {
                        cseq_diff: 1
                }
        }
}

Jul 28 09:27:30 ip-10-0-0-2 /usr/local/sbin/kamailio[11061]: NOTICE: {2 450917085 BYE
a9d32620-2b68-1238-048a-0cc47a18705a} acc [acc.c:279]: acc_log_request(): ACC: transaction
answered:
timestamp=1564270050;method=BYE;from_tag=SD5ptp899-1177933201-1564269931305;to_tag=mjKtcKaBteQ4Q;call_id=a9d32620-2b68-1238-048a-0cc47a18705a;code=404;reason=Not
here;src_user=0400123123;src_domain=trunk.remote;src_ip=trunk.remote;dst_ouser=0400123123;dst_user=0400123123;dst_domain=kamailio.public-ip

I’m assuming the 404 is because the Contact header I sent from Kamailio -> Trunk is
rewritten, that Contact is Kamailio’s public contact IP. However the dialog has the caller
contact within it referencing back to the local PBX, so I would think when Kamailio gets
this dialog ID back with a BYE it would relay it back to the original contact, wouldn’t
it?

Thanks!

Andrew