A Storm that swept across the Eastern Seaboard and the US Midwest on Sunday caused AT&T lots of problems with some customers not being able to access voice or data services, and others having disruptive calls, AT&T said that it was down to a power failure in Bloomfield Mich.
AT&T customers complained on various tech websites to rant about not having a service, with some complaining they had no 3G network either. Luckily AT&T restored the power later with a backup system so by Sunday afternoon there service was completely restored.
The service being down at AT&T came at a really bad time, with the iPhone 3G selling at Wal-Mart at a bargain price on the same day. So the failure upset lots of people who had just brought their brand new iPhone.
Source: informationweek