Help Using AT&T Version on T-Mobile?

[zoomxzoom]

So i recently bought an at&t s3 & unlocked it & started using it on tmobile, everything works, except for the internet. I only get EDGE speeds, when i'm supposed to be getting 4G. I know i have 4g coverage because it worked on my old phone. The s3 is an amazing phone but the slow internet is ruining it, & i really don't wanna have to switch back to my htc ): can anyone help, or is it impossible to get 4G?

 

[tchen811]

Tmobile does not have LTE if that's what you mean by 4G.

Also the S3 has different radios between AT&T and Tmobile versions. Maybe that's why you don't get Tmobile speeds...