Fritz 7590 not responding to SIP INVITE

I have just been migrated by Zen from ADSL to FTTC. I have had a number of breezy e-mails telling me that everything went swimmingly and the migration is complete. Sadly, my bundled telephone service isn't working: incoming calls are not ringing the house telephone connected to the FON socket with the appropriate adapter. It seems that Zen attempted to provision my router with the appropriate parameters, but this was unsuccessful. It's a Fritzbox, their preferred, but not the exact model they supply. (There are good historic reasons for my product choice that aren't relevant here.) Using the tcp dump facilities on board the Fritzbox, I can see the SIP INVITE messages arriving when I ring my "land line" from a mobile phone. The fritzbox does not respond (or at least no such traffic appears in the trace). I have tried all sorts of settings - a total of around 12 hours of fruitless effort. Zen support are, as ever, delightful and willing, but ultimately of little tangible assistance. Can anyone else help? Perhaps with screenshots of the relevant configuration screens from a fritzbox where the automatic provisioning was successful?

In reply to a post by Catsmum:

It seems that Zen attempted to provision my router with the appropriate parameters, but this was unsuccessful. It's a Fritzbox, their preferred, but not the exact model they supply. (There are good historic reasons for my product choice that aren't relevant here.)

its possibly a firmware configuration mismatch - especially if Zen are provisioning files to a router which is not what they have previously tested etc.

What happened to the Frtizbox that they supplied?

I am using a 7590 for VoIP (A&A for incoming, FreeVoipDeal for outgoing), works fine for me.
If you want, I can have a look at your tcpdump.
You can also save an extended support file which should have all the SIP messages already decoded which may be more useful.

Have you configured the phone under Telephony >Telephony Devices
if not, there is a button in the bottom right corner "Configure New Device" and follow the wizard, it will also test whether the phone rings

Edited by essex_man (Thu 27-Aug-26 17:18:28)