Just got off the phone with business customer care (usually they're better than normal customer service with AT&T). He said the problem is iTunes servers where they connect with AT&T are overwhelmed and keep crashing. That Apple gave all three US carriers basically separate channels to access the iTunes servers, and that since AT&T has by far the most iPhone users of the three carriers, they're hammering their portion. He said that if it was a problem on their end that other phone types wouldn't be able to activate, but that's not the case at all. That any phone except an iPhone will activate. FWIW.