As indicated, I have a 3GS and haven't bothered to upgrade. I am inheriting a 4S from a family member who for work reasons is moving to either a windows or android phone. This is good for me since I get a "newer" phone without having to extend my contract! (It's possible I might eventually buy the new phone later this year but at the moment I'm in no hurry.) Anyway...if I remember correctly, the 4S uses a different SIM card than my 3GS? If so, what should be my upgrade procedure/process? I'm presuming that when my family member gets a new phone that AT&T will deactivate the SIM in the 4S. So I will then need to get a new SIM from AT&T before I can transfer my data to the 4S? I have just been in iTunes and confirmed backups to iCloud and to my PC from today. If I'm at an AT&T store with my family member should I have the staff do anything while I'm there? Will they be able to give me a SIM card and add the 4S IMEI to my account without automatically deactivating my 3GS? Thanks for any tips.