I wasn't sure if this question belonged in general or here, so I played it safe and came here. The story is this: I upgraded to a 4S 16GB in January and now regret it. I'd rather have a 32GB unit. Obviously I can't return it or re-up with AT&T. I see them for sale on Craigslist all the time and have toyed with just getting one and swapping my old one out, then selling it. The question is, what do I have to do? Just switch SIM cards? AT&T has tied the 16GB model to my account. So I'm curious as to the process, if it's legal. I'm not interested in a jailbroken phone.