Originally Posted by Rootmepls
I just traded in an iPhone for a Samsung Captivate. Not sure about your carrier but I asked at AT&T if my SIM would work in both phones (thought it would be cool to switch it back and forth sometimes). They said no. I guess with AT&T the iPhone unlimited and the "Other" smartphone unlimited are two different plans and they are not switchable. At least thats what I was told by the salesperson. Haven't really tried it myself to see if its true.
it's bs. you can switch back and forth provided you have an adapter for the iphone4's micro sim card. on an iphone 1g, 3g, 3gs you can switch it no problem.
i did it with my captivate and even now my inspire that i purchased off contract (had an upgrade but didn't want to burn considering how cheap the phone is)