andyit:

 

I appreciate you checking, however I need to be precise about the timeline. I ran this exact test two days ago using identical parameters — resolver 8.8.8.8, same hostname — and received a clear NXDOMAIN response. Today it resolves to 118.149.14.20, which is identical to the proprietary address epdg.ims.2degrees.net.nz — the same gateway, just now accessible via the standard GSMA address.

 

I've independently confirmed UDP 500 and 4500 both succeed on the standard address — again pointing to the same infrastructure.

 

However VoWiFi still fails to complete on my device on 2degrees despite DNS now resolving and both IKE ports responding. The barrier remains at the authentication layer. A $2 SIM and I am up and running on another carrier straight away.

 

Something changed between two days ago and today. I'll leave the timing and conclusions to others to consider.

 

@andyit, months back, I found 2degrees' VoWifi a bit unreliable.  Sometimes it works, sometimes don't.

Lately it is more reliable.

There was a time (few weeks back), I made it work again by:

• turn wifi calling on
• turn wifi on (at that point few weeks back, VoWifi did not work)
• turn mobile data off
• turn GPS / location on
• wait for a minute or so
• and then restart the phone

I need to have GPS turned on when I restart the phone, otherwise VoWifi would not work (back then).

You may want to give it a try.  :)