Unlocked Att S6 trouble making calls on tmobile

[Android Central Question]

Hi,
Just took my phone from Att to tmobile. Its a Samsung S6 I used without issue that once unlocked and put in tmobile sim, calls dont go through. It was dfor my son so you can imagine the disappointment. Data seems to work fine.
Thanks-
Mike

 

[B. Diddy]

Welcome to Android Central! Go to Settings>Mobile Networks>Network Operators -- is T-Mobile selected?

 

[burke0539]

I'm the original poster. Yes it has T-Mobile as network.

 

[B. Diddy]

Look in Settings>Mobile Networks and see if VoLTE is turned on or off. On AT&T, it might be called HD Voice. Other names for it are Advanced Calling and Enhanced 4G. Whatever it's set to, try the opposite.

 

[burke0539]

Nope. doesnt work hd voice on or off

 

[B. Diddy]

Who unlocked the phone for you -- AT&T or a 3rd party?