Unless it was an AT&T phone, T-Mobile can unlock it. You just have to wait 90 days to do so. In the future, don't go to indirect dealers, or take the phone out of the box before you get it home and see if it will work. After 90 days just call T-Mobile and they'll put in a request. It's free.

I hope someone can help. I brought an unused Motorola cell phone into a TMobile store to be "unlocked". A week later they are telling me it cannot be done. But now they have me locked into a year long agreement with no phone. Any advice on what I can do? Is unlocking phones illegal? Can I insist that they give me a phone for free and let me out of the agreement since they did not fulfill their end of the agreement? They gave me a free loaner but I am uncomfortable with them hanging onto the other phone.
Please help!