My sister has a first gen iPhone and plans on getting a new iPhone, she's actually waiting until summer to see what Apple does with the iPhone. So when she upgrades, she said I can have her old iPhone. I know I can't just put my SIM card in the iPhone and it will all work. I've already read that, but how do I activate it again with my number so I can call, text, surf Safari and all that? Do I have to take it to AT&T? Are they going to charge me?