AT&T Mobility is the wireless subsidiary of AT&T and is headquartered near Atlanta. It is the second larges wireless telecommunications provider in the U.S., with over 95.5 million subscribers. In 2004, AT&T Mobility (then called AT&T Wireless) was purchased by Cingular Wireless LLC, a joint venture between SBC Communications and BellSouth. SBC then acquired the original AT&T parent company and renamed itself "The New AT&T." In 2006, the new AT&T acquired BellSouth and became the sole owner of AT&T Mobility. In 2007, Cingular was re-branded under the AT&T moniker. AT&T Mobility is known for its Rollover Minutes service which allows customers to retain unused minutes from month-to-month. AT&T Mobility was the first carrier to sell the Apple iPhone, and sold it exclusively from its release in July 2008 until February 2011. The latest version of the iPhone, the iPhone 4, features an upgraded camera, flash, a new exterior design, upgraded screen, and the new version of Apple's software. In addition to smartphones that run on the iOS mobile operating system, AT&T Mobility also sells smartphones based on Google's Android, Windows Phone 7, and Palm's webOS platforms. AT&T Mobility's popular phones include the iPhone 4, Blackberry's Bold and Torch and the Motorola Backflip. On March 20th, 2011, AT&T announced plans to purchase T-Mobile USA from Deutsche Telekom for $39 billion in cash and stock. Source: SEC Filings