I need help! (New user)

[Cell Queen]

Okay, so I bought this new flip phone last year, and the company pretty much pulled all the stops they could trying to make sure that I didn't get the deal I was promised when I bought the phone, despite the fact that I pretty much got everything down to the letter on their stupid rebate. *coughcough*Tmobile*coughcough*

Now I switched to another network and got a GO Phone. The service is good, but the GO Phone itself is a piece of **** and I can't make long distance calls on it without static. Is there any way I can switch the SIM cards so that I have the GO Phone service in the old flip phone? Or do I have to go to an AT&T store to have that done?