My brother and I both have iPhone 4s, with the same plans(unlimited data), and he was eligible for an upgrade but I was not. Since he doesn't want the 4S, I used his upgrade to order mine. When I get mine tomorrow, can I just swap the SIM from my iPhone 4 into my new 4S and activate the phone? I don't see why I would need to call AT&T frankly, the less I have to deal with them, the better.