There are some who have managed to get a USC phone to work on TMobile GSM but only at 2G speeds. It requires root and some complex tweaking. Not for the faint of heart.
This may or may not work for you and could end up making your phone worthless. Proceed at your own risk.
Fully working Verizon S3 on T-Mobile - xda-developers
You'd probably be better off in the long run to get a phone designed for your carrier.
This may or may not work for you and could end up making your phone worthless. Proceed at your own risk.
Fully working Verizon S3 on T-Mobile - xda-developers
You'd probably be better off in the long run to get a phone designed for your carrier.