[Blink] On re-invite ACK not reaching callee

[Robert Dyck]

On Tuesday, August 25, 2026 12:51:51 a.m. Pacific Daylight Time Adrian Georgescu wrote:
> Do you have the call id?

*Call-ID: 84babaaa-f198-4b53-989d-98d2829946c7*

Is signaling recorded?
> 
> > On Aug 24, 2026, at 22:46, Robert Dyck <rob.dyck at telus.net> wrote:
> > 
> > Using latest flatpak for Linux.
> > 
> > Caller on sip2sip.info calls subscriber at a different domain. Callee
> > answers and dialog is established. So far all good.
> > 
> > Caller does a re-invite ( hold ). The callee's UA sends 20OK. Caller's UA
> > sends ACK. ACK never arrives. Callee's UA continues sending 200OK.
> > 
> > Callee is registered as GRUU. Incoming requests are normally translated by
> > the local registrar and the request is forwarded to the callee's IP
> > address. This also applies to re-INVITE and its ACK. The caller learns
> > the registrar's address from the Contact it previously received in the
> > initial 200OK.
> > 
> > Summary of in-dialog requests
> > Initiial ACK - OK
> > re-InVITE - OK
> > second ACK - doesn't arrive
> > Bye - doesn't arrive
> > 
> > An important detail - Registrar/Proxy is behind NAT. Router use DMZ
> > forwarding.
> > 
> > The request URI of the ACK following re-INVITE is pointing at the external
> > address of the registrar but the ACK was received at a private address.
> > The ACK is forwarded to the external address. It never reaches the
> > registrar because the router cannot hairpin the forwarded message.
> > 
> > ACK
> > sip:8 at external-address:5060;gr=urn:uuid:38ee02db-f267-4dd9-9077-1b9d4fcfb
> > f00 SIP/2.0> 
> >                                                            Record-Route:
> >                                                            <sip:212.95.45
> >                                                            .179;lr;ftag=80
> >                                                            3fbe29-6196-4af
> >                                                            7-9771-db7d2500
> >                                                            7e6c>
> >                                                            Record-Route:
> >                                                            <sip:174.142.2
> >                                                            05.46;r2=on;lr;
> >                                                            ftag=803fbe29-6
> >                                                            196-4af7-9771-d
> >                                                            b7d25007e6c>
> >                                                            Record-Route:
> >                                                            <sip:174.142.2
> >                                                            05.46;transport
> >                                                            =tcp;r2=on;lr;f
> >                                                            tag=803fbe29-61
> >                                                            96-4af7-9771-db
> >                                                            7d25007e6c>
> >                                                            Via:
> >                                                            SIP/2.0/UDP
> >                                                            212.95.45.179:
> >                                                            5060;branch=z9h
> >                                                            G4bK45c1.804d44
> >                                                            d2.2
> >                                                            Via:
> >                                                            SIP/2.0/UDP
> >                                                            174.142.205.46
> >                                                            :5060;branch=z9
> >                                                            hG4bK45c1.ab795
> >                                                            fa4.2;i=d0969e0
> >                                                            7 Via:
> >                                                            SIP/2.0/TCP
> >                                                            192.168.1.3:58
> >                                                            491;received=ex
> >                                                            ternal-address;
> >                                                            rport=58491;bra
> >                                                            nch=z9hG4bKPj62
> >                                                            eb9faf-6eba-4f9
> >                                                            1-9539-8b2954ca
> >                                                            d94a;a> 
> > lias
> > _______________________________________________
> > Blink mailing list
> > Blink at lists.ag-projects.com
> > https://lists.ag-projects.com/mailman/listinfo/blink


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