iPhone XS Max: Calls only working over WiFi

Hey I gotta a iPhone XS Max 64gb on T-Mobile, my iPhone is activated internet and everything works fine when not connected to WiFi, calling on the other hand is a no go, anytime I try to call someone not using WiFi calling it simply doesn’t work, I can’t hear the ringer after I press the call button, I press the speaker button and it instantly turns right off, sometimes I can hear them and they can hear me but very distorted. But anytime I call someone over WiFi it’s crystal clear works perfectly fine, let it noted that I’m in full bar lte radius so I shouldn’t be having these problems, i know it’s not t-mobile either, because I took the SIM card out of this phone and put it in a unlocked google pixel 3a and works fine. Does anyone know the reason for this? Thanks!