Wifi calling on unlocked d850

I have a question about getting wifi calling. I moved into a new apartment and my signal is awful. I have an att g3 (d850) that I have unlocked onto Tmobile, and I was wondering if either it was possible to succesfully use a d851 rom with wifi calling on my g3 or some other way to get that feature. Not having signal is extremely frustrating so any help would be apprecited