VoWifi - Unable to Make calls using wifi when Public IP changed

[jimzey74]

Hi, I work in the UK and we are in the process of migrating our Internet exit point for a set of wifi users.

We have a mix of providers, Vodafone, Three, O2 and EE as you might expect. On the existing Internet link, wifi calling works across all of them.

When we move to the new public IP wifi calling fails for EE, all other vendors work.

I have ran a trace and can see IKE being setup to the EPG.. phone just won't set up the call and say call failed.. all traffic is allowed outbound on the firewalls.. 

EPDG

109.249.188.56	United Kingdom	EE Limited
109.249.190.48	United Kingdom	EE Limited

immediately after a DNS lookup for the EPDG endpoints, I can see a query for geomobileservice-pa.googleapis.com 142.250.179.170.

I do see a TCP reset coming from 172.217.168.196 (www.google.com), but it looks like the IKE session to the EPDG doesn't complete for some reason.

I am thinking that perhaps EE use a Geolocation service which places or IP outside of UK which then invalidates the terms of service for EE Wifi calling so drops the session.

This is the only thing I can think of. 

1. Does anyone know what geolocation service EE use to verify that the client is calling from the UK?

2. Has anyone else seen this or a similar issue.

thanks 

[bristolian]

Hi @jimzey74 

It's entirely feasible that EE are using geolocation for VoWiFi, if they do then the details of that would be commercially sensitive.

All I can really add is general comments around location data for IP addresses sometimes taking a little while to play catch-up after being updated.

I've never tried using WiFi-calling outside of the UK, so am not sure where a failure would be induced - I would expect it to simply not allow an attachment in the first place.

Who is the underlying provider that you're using for onwards connectivity?

[jimzey74]

thanks for the reply, this is very frustrating .. what would be the cause, do EE do any whitelisting of public IPs and where to accept call registrations from do you know?