My wife and I both have 1st gen iPhones on the family talk plan. I want to upgrade to the iPhone 3G and give her mine because the glass on hers is broken. How do I go about doing this? Is it as simple as me going and buying a new iPhone, activitating it with my new SIM at the Apple store, then taking her SIM and putting in my old iPhone and activating it on itunes? Or do I have to go to AT&T and have them do it at a fee?