[SR-Users] Dialog missing when BYE is received from trunk

Andrew White andrew at uconnected.com.au
Sun Jul 28 01:54:17 CEST 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 at pbx.local:5060
        to_uri: sip:61400123123 at
        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
                socket: udp:
        callee: {
                tag: SD5ptp899-1177933201-1564269931305
                contact: sip:SDd3mt8-nn9jnirnmqcrvfmvkpm0hmhvgggjgv2io788of70s84u9 at trunk.remote:5060;transport=udp
                cseq: 0
                socket: udp:
        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?


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