I have an iphone right now, can I just buy another smartphone and put the SIM card into the new phone and it'll work? Or do I need to get any new phone activated before it can be used? I'm getting the Captivate when it's out, and might start messing with it in terms of rooting and custom ROM's and stuff like that, and also might want to develop apps myself. If I do this I will want to have a backup phone in case my Captivate gets temporarily fucked from the tinkering. Dataplan is not an issue since I already pay for the iphone dataplan, with unlimited data, and i'm not looking to do anything shady.