Hello, I have an OG Pixel (Pixel 1) and I had been on Google Fi but recently switched to Xfinity Mobile (Verizon MVNO) and can't get the wifi calling to work. Xfinity mobile says that it is activated on their end. It's activated on the phone. I checked the Testing Menu (dial *#*#4636#*#* on dialpad) and Wifi calling is provisioned (it's also grayed out so I can't change it).
So, when I put the phone in airplane mode and try to make a wifi call I get the message, " turn off airplane mode or connect to a wireless network to make a call".
I'm on Android 10. I've gone through this forum and tried the suggestions that others have had with similar problems on Verizon, but can't find anything that works.