I am currently using an iPhone 4S with ATT. My 2 year contract does not expire until November. However, I wish to sell my iPhone now because the value will go down when the new iPhone is announced. My friend has an ATT iPhone that they will lend me for a couple months until I buy the new iPhone. I have never sold a phone before. Do I simply just restore it back to factory settings and remove my SIM card? If I put my SIM card into the iPhone I am borrowing will I just be able to use it and my number will roll over to that phone? If anyone has experience selling their iPhone before their contract with ATT is up please let me know what I need to do.