If my friend has a blackberry, and I give him a 3gs, will I be able to just swap the sim into the iphone? Or do I need to call at&t to get it set up? Only reason I ask is because i know I had to call to set the BB up for the bb server or whatever.
You're gonna have to switch the data plan from Blackberry data to iPhone data. You can do this online or over the phone. I'd call them though, to make sure that unlimited data doesn't go anywhere.