VoLTE is working for me on TMobile same with WiFi calling. Can't say for sure if it would on AT&t but don't see why it won't. One way to find out is check the Moto site they do list some compatibility or ask Moto support. They confirmed those things would work on tmo for me.
Sounds like a way to get people to buy phones from their stores at their prices.There is a big reason why not
Unlike Verizon and T-Mobile, ATT is more strict on certification for VoLTE. All of my unlocked Motorola phones (From Moto X, XPE, to z/z2 play, G5S) had VoLTE with VZW and none of them with ATT. I didn't even have to trick them with IMEI or anything.
It's all over the forums. There are very few devices that are certified. Pixel line, essential phone, Z3 play and a few other models.
Sounds like a way to get people to buy phones from their stores at their prices.
Not sure if I have VoLTE or not as I never really thought about it. How do I check that?