Metering and Billing Wireless Data for 20M Subscribers is not Trivial

  
Few months ago a lawsuit was filed against AT&T claiming that (see video below from NBC's Today show) - " .. the company's billing system records data use up to three times the actual use, including "phantom" charges that occur when the phone is not in use".

See report by Chris Foresman (picture) to arstechnica - "How a law firm tested "phantom" AT&T smartphone data use"  - here. 
 
The article presents the "The independent tests were conducted with multiple devices over a period of four months, and allegedly show that AT&T's billing system regularly recorded data use that exceeded actual use by 7-14 percent, on average. In some cases, AT&T reportedly recorded data use as much as 300 percent of the actual use. To confirm the "phantom" data charges, a computer engineer hired by the law firms involved in the case took a brand new iPhone, turned off all push notifications and location services, did not set up any e-mail accounts, and made sure no applications were running. After 10 days of sitting idle, AT&T recorded 35 instances of data use totaling over 2MB".

AT&T spokesperson Seth Bloom said that "all activity, including checking e-mail, Web browsing, and streaming music, uses data. But so do many mobile apps, such as weather apps and stock tickers, which update using data from the network. Games connect to networks like Game Center, and visual voicemail services download data from the network. The company also claims data could be transmitted or received by background processes that users simply aren't aware of .. AT&T captures your data activity nightly to create a bill record in our systems .. This will appear on your bill to be a late night 'charge,' but in fact, the time stamp reflects the time that your device established a connection to the [billing system], not the time that you sent or received data."