I have a question and it is serious! I don't want to ask an att rep or an apple rep because i would hate for them to flag my account. Anyways i am not eligible for an iPhone until 3/10/10 but my sister is eligible for an upgrade now, so if she were to buy the iPhone 3GS and i give her my iPhone 3G and we just swapped sims would both of our phones still work and the thing im most interested in is would i still be eligible for an upgrade next year even though my sister and i switched phones? Would they be able to tell? And would the iPhone 3GS restore from a 3G back up?! Thank you!