Question [Q] WiFi calling on a&tt varient.

Hey guys. I have become increasingly frustrated with having no way to root this phone coming from a nexus in favor of battery life.
I was wondering if getting an ATT version and using it on t-mo towers is a good option seeing as that one is rootable. The thing I'd like to keep is WiFi calling as my office is a dead zone. Is the WiFi calling part of the radio? Is it hard ware specific? Just wanting some light shed on this issue. Thanks.