I’ve switched to Virgin (O2) and the wifi calling options are missing under Mobile network.
I added them from Dev options.
They now show but never “engage”. I can set wifi calling on, but the moment I leave the screen it turns off again.
I’ve phoned Customer support on 789 and asked them to enable wifi calling on my SIM.
I’ve just accepted the FP4 Android 13 update and the WiFi calling icon now appears for O2 when it’s set with WiFi calling on and the make calls over WiFi option is selected, time will tell if it actually works …