I got to this instant messaging thing ATT has for customer service. I don't know how much we can trust this, but here's what went down: ME: if I do purchase a Bold, would I be able to switch the SIM cards if I wanted to use my iPhone to say, watch a movie or something? Karen L.: Yes you would be able to add your sim card to the new phone. ME: and switch back to the iPhone as needed for multimedia purposes? Karen L.: Yes you can.