When they get shipped to you from AT&T I understand the phones already have a SIM in them so I assume it is already programmed with your phone number from AT&T and tied to your account. All you have to do is activate it on iTunes. In order to sell the phone without opening the box what needs to be done? Or can't it be done? Do you have to open the box and remove the SIM before selling it? I am getting 2 3GS's and want to sell off 1 of them (my wife is happy with her 3G). I was hoping I wouldn't have to open the box and remove the SIM.