I've been using my iPhone on AT&T GoPhone for 6 months, after following the trick on unlockit.co.nz. This worked with no trouble! Great data rates and a good voice plan too. However today I got a message saying my data plan is depleted. I rang up to complain and the AT&T rep said that they have updated their system and are now kicking off iPhone users. She added another 50MB for me to test with. It work for a few mins then I got another message saying my data plan was depleted. Is anyone else finding this? Is there a new work-around for using the iPhone on AT&T prepaid GoPhone?