<html aria-label="message body"><head><meta http-equiv="content-type" content="text/html; charset=us-ascii"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Do you have the call id?<div><br></div><div><div><br><blockquote type="cite"><div>On Aug 24, 2026, at 22:46, Robert Dyck <rob.dyck@telus.net> wrote:</div><br class="Apple-interchange-newline"><div>
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<div><div style="margin: 0px;">Using latest flatpak for Linux.</div>
<br><div style="margin: 0px;">Caller on sip2sip.info calls subscriber at a different domain. Callee answers and dialog is established. So far all good.</div>
<br><div style="margin: 0px;">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.</div>
<br><div style="margin: 0px;">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.</div>
<br><div style="margin: 0px;">Summary of in-dialog requests</div><div style="margin: 0px;">Initiial ACK - OK</div><div style="margin: 0px;">re-InVITE - OK</div><div style="margin: 0px;">second ACK - doesn't arrive</div><div style="margin: 0px;">Bye - doesn't arrive</div>
<br><div style="margin: 0px;">An important detail - Registrar/Proxy is behind NAT. Router use DMZ forwarding.</div>
<br><div style="margin: 0px;">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.</div>
<br><div style="margin: 0px;"><span style="background-color:#ffffff;"><strong><span style="font-family:monospace;"><span style="">ACK sip:8@</span><span style="color:#ff0000;">external-address</span><span style="">:5060;gr=urn:uuid:38ee02db-f267-4dd9-9077-1b9d4fcfbf00 SIP/2.0</span></span></strong><span style=""> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Record-Route: <sip:212.95.45.179;lr;ftag=803fbe29-6196-4af7-9771-db7d25007e6c></strong> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Record-Route: <sip:174.142.205.46;r2=on;lr;ftag=803fbe29-6196-4af7-9771-db7d25007e6c></strong> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Record-Route: <sip:174.142.205.46;transport=tcp;r2=on;lr;ftag=803fbe29-6196-4af7-9771-db7d25007e6c></strong> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Via: SIP/2.0/UDP 212.95.45.179:5060;branch=z9hG4bK45c1.804d44d2.2</strong> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Via: SIP/2.0/UDP 174.142.205.46:5060;branch=z9hG4bK45c1.ab795fa4.2;i=d0969e07</strong> </span></span><br><span style="background-color:#ffffff;"><span style=""> <strong>Via: SIP/2.0/TCP 192.168.1.3:58491;received=external-address;rport=58491;branch=z9hG4bKPj62eb9faf-6eba-4f91-9539-8b2954cad94a;a</strong></span></span><br><span style="background-color:#ffffff;"><span style=""><strong>lias</strong></span></span><br></div>
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