So now with Vodafone dropping SureSignal support they have finally enabled wifi calling- nice!

However, one problem with this that I didn't foresee is that at home with my SureSignal off my iPhone 11 now spends ~50% of its battery every 24 hours just searching for mobile coverage, even though its got full wifi signal. I can get around this by turning on Aeroplane Mode but remaining connected to wifi. Its a bit annoying turning Aeroplane Mode on/off when I arrive/leave home but I can manage it with some ios automations. Messages and calls come through over the wifi and my battery isn't drained by constantly searching for cellular signal - problem solved! (through a non-ideal workaround)

The problem is my wife's iPhone. Her iPhone SE2 does not respond the same as my iPhone 11 and she is at home most of the day so the battery life issue affects her more. Her iPhone will not allow you make or receive calls or SMS messages when on Aeroplane mode, even though it is connected to wifi. If you try and make a call it prompts you to turn off Aeroplane mode first. And SMS messages dont get through even with full WiFi reception.

I've checked her phone and it seems to be set identically to my phone. Does anyone know of any hidden settings that might be causing these differences in behaviour? Or is it perhaps a different setting on Vodafone's end for different devices?

I'd really like to try and get this sorted otherwise it looks like for reception-compromised people that WiFi calling is actually a poor replacement for the SureSignal