iphone 4s on Tmobile not getting 3G
I have an unlocked iphone 4s on tmobile's network. I have a micro sim card in the phone, from tmobile, and am only getting EDGE not 3G and i'm in a 3G area. I was told i could get 3S with an unlocked phone. Is there a way to do this so i'm on 3G and not EDGE?