AT&T was sold out yesterday a little before 6pm EST. They sold their share in a little over 14 hours. The same was true with supplies almost ever where. The initial sales numbers would have been well over 7 per second world wide. AT&T could have used some cloud based hosting for some of the extra demand, and that might have let them sell out even quicker. But with over 10x more demand this year, that's hard to account for. And they likely sell more units overall because now the iPhone is the "it" thing to get. There's nothing like a delay and hundreds of thousands of orders in a few hours to spike demand even more.
AT&T is the cloud