I recently joined O2 from Three, because Three are turning off their 3g network and I stopped being able to make any calls. I have a Sony Xperia 1ii which I believe is capable of 4G calling but this did not work on Three's network. Three has no 2G to fall back on.
On O2 I can use my phone again, because O2 are yet to turn off 3G. However, I would like to know that my phone still will, once this happens.
There are no options in my phone settings that allow me to enable/disable 4G calling.
I just spoke to O2's technical support. They told me to look through the settings which (as I already knew) revealed there was nothing I could turn on or off.
The advisor then asked me if I could access mobile internet whilst on the call with him. I could. He said this meant that my phone was already using 4G calling. I pointed out that while on the call, the symbol in the top menu bar is "H+" not 4G, suggesting the call was going through an H+ connection not a 4G one.
He assured me that no, that doesn't matter; if I can use mobile internet whilst on a call, this means my phone is using 4G calling. I was sceptical but said ok and ended the call.
However ... if I change my "Preferred network type" to "4G/5G" I am unable to make any calls.
Does this not confirm that I'm correct - my phone is not making 4G calls?
(I have tried doing the *#*#4636#*#* code and there is a switch next to "VoLTE provisioned" but it's turned off and greyed out.)
