iPhones are apparently not compatible with many, perhaps all Microcells. Mine failed last week when I first activated my 4S. A number of calls to AT&T and plenty of promises of repair have been made. If you go to the activation page on AT&T's website you'll notice that apparently AT&T feels that the 4S is not 3G capable when it clearly is. I am at my wit's end now because I have no phone service at home. At this point it may be worth it for me just eat the costs and get out of AT&T. We pay hundreds of dollars for non-existent service.