So, here's the story. I have a 4S, my girlfriend has a 16gb iPhone 4. I'm going to purchase the iPhone 5 for contract price + $250 because neither of us are currently eligible for an upgrade. What I would like to do though is giver her my 4s, and sell the 16gb iPhone 4. As you probably know, if I can get it unlocked, resale value will be much greater. Will AT&T unlock this phone for me after we both make the switch? I should mention currently my girlfriend and I are not on the same account.