A California man has sued AT&T for over billing him on data charges for his iPhone, a move that could raise new questions on the carrier's billing practices. Patrick Hendricks claims that the carrier was charging him for usage even when he wasn't using any.

Hendricks uses the $15 monthly 200MB plan, and apparently became suspicious after he was charged overage fees for using 223MB worth of data across 259 data connections. His lawyers say that their research showed that AT&T was regularly over billing customers between 7 and 14 percent over actual data usage, and in some cases as much as 300 percent.

AT&T's billing errors on a customer basis may not be that large. However, apply that across all iPhone customers and it has a "huge effect" on the bottom line for the company, Hendricks' lawyers claim in the suit. "A significant portion of … data revenues were inflated by AT&T's rigged billing system for data transactions," they wrote.


A test iPhone account found that even with all apps closed, push and location services disabled, and the device unused, AT&T billed the account for over 2,292KB of usage over a period of ten days. "This is like the rigged gas pump charging you when you never even pulled your car into the station," Hendricks' suit continues.

While it may not be out of the realm of possibility that those "phantom" data charges may be necessary between the smartphone device and the network itself, it still gives critics yet more ammunition to fire at AT&T regarding the handling of the iPhone.

This is not the first time the carrier's iPhone polices have come under fire: at least a half dozen suits have been filed over the company's 3G speed claims, and last year the AT&T exclusivity agreement and it's alleged knowledge of iPhone 4 antenna problems were challenged in court.

Hendricks is asking for compensation, and also for class-action status for his suit. If that occurs, AT&T could become liable for over billing all of its iPhone users -- a potentially costly settlement.