I received my sisters old 3G for free since she was given a new 3GS from work. I had it unlocked and jailbroken and was now thinking about selling it to make a few extra bucks and then just buying a new 3G at retail price. However, I'm not exactly sure on a few things.

Would I have to get a new contract for the new phone or could I just put my current SIM card in the new phone and use it, no questions asked? Are there any extra fees I'd have to pay?

Any help is appreciated.

See More: RE: Selling an iPhone and buying a new one.