Got a guy here at work that has T-Mobile. He is wanting to get an iPhone unlocked to work with T-Mobile. Needless to say most everything out there is crazy expensive. So here is my thought, tell me if I am missing something, I sell him my current 8gig iPhone unlocked for $400 and then I go to the Apple store and buy myself a 16gig iPhone and use my current SIM. The main question I have is can I go to the Apple store and purchase another phone and put my already activated SIM in it?