Wifi calling is not working

[rogercorke]

My wife and are both have iPhones - her's a first generation SE, mine an iPhone12 mini. We're both on the same Apple account and both use wifi calling. It used to be fine until we changed to Virgin media, since when her's works fine on Wifi calling but mineine hardly ever works - usually just flashing up with the Wifi calling logo on the home screen from a few seconds before disappearing. So far, I have updated my IoS, reset my work settings, turned Wifi calling on and off, turned mobile data on and off, turn airplane mode on and Off (someone suggested it online!) and spent hours on the phone to Virgin Media. I still have no wifi calling 95 per cent of the time.

The only difference in the settings I can find between my iPhone 12 mini and my wife's iPhone SE is that, if you go to Settings, Mobile Data and Mobile Data Network, my Mobile Data APN is goto.virginmobile.uk whilst my wife's is wap.vodafone.co.uk. We have a Vodafone broadband router.

Even if I change my settings to wap.vodafone.co.uk, when I go down to the bottom of that screen and press Reset Settings, mine reverts to goto.virginmobile.uk. When I reset my wife's phone in the same way, her Mobile Date APN remains at wap.vodafone.co.uk.

Both our MMS APN settings are goto.virginmobile.uk.

Before I throw my iPhone out of the window, can anyone suggest anything else I can try?