Last year I purchased a 3GS, and had the same data issue. I have now upgraded to a 4s, and am hoping the data problem can be resolved. It is a 4s, running iOS 6.0.1 on ATT prepaid (and modem firmware is 3.0.04, if that is important, it has been in the past..) Text and calls work, however I get this when I try to use data.. This is the same message I received a year ago too, and the resolution involved altering the apn or something. Although apparently with iOS 6 apple made it so you cannot do that anymore? (By the way, picture messages do not send, either) If anyone has solutions, thanks a lot!