I'm not convinced that using the Go-Phone plans with the iPhone is such a good idea. While you don't have the contract, it's not a very good deal for what you get, first of all. Plus people say that they are pestered by messages telling them how much they have used, even if they haven't used anything. I also don't know if it's possible to cancel an account that's already been activated and then switch to the prepaid plan. You might want to call AT&T about that.