Thank you for your interest (and prompt attention).
I have reviewed the Gigaset configuration screens but can see no mention of anything NAT related.
It is strange that there is no SIP traffic showing in my original trace. As I am not immediately in a position to undertake a further "Talk Talk" capture, by way of an experiment I tried ringing my VOIP landline from my mobile whilst initiating a capture in the form previously advised.
This later capture clearly shows a SIP/SDP invite request with my mobile number and AAISP VOIP user name visible, as well as the disconnect instruction upon termination, so it would appear to be correctly configured.
I think the only logical way forward it to once again try a "new" capture, this time with a longer pre/post capture period (unfortunately with inevitable further delay)
Edited by farrinaf (Tue 08-Dec-20 12:12:16)