AT&T Mobility LLC (usually branded AT&T, and formerly named Cingular Wireless LLC) is the wholly owned wireless subsidiary of AT&T Inc. AT&T Mobility is the largest mobile phone company in the United States and it also operates in Puerto Rico and the United States Virgin Islands. AT&T Mobility has approximately 70.1 million subscribers as of the year ending 2007, and claims to operate the largest digital voice and data network in the United States. blank">"About us" at wireless.att.com

Formerly a joint venture between SBC Communications and _BellSouth, Cingular Wireless soon acquired the old AT&T Wireless; SBC later acquired the original AT&T and rebranded as "the new AT&T". Cingular became wholly-owned by the new AT&T in December 2006 as a result of AT&T's acquisition of BellSouth.

The service is now branded as simply AT&T. Renaming on a corporate level occurred immediately, and consumer branding changed to "AT&T", or a variant thereof. Until all regulatory filings were approved, and public awareness was fostered, the "Cingular" brand was used in store signage and media advertisements during a dual-branded transition. This process began on January 15, 2007. "blank">Cingular is now the new AT&T." AT&T Press Release. January 12, 2007. It completed in late June, just prior to the rollout of the _Apple iPhone.

Among the services that AT&T aggressively promotes is its "Rollover" service, allowing customers to keep unused minutes from month to month on a twelve-month rolling cycle on its popular "Nation" nationwide plans. Beginning in July 2007, AT&T now allows its AT&T Unity plan users to have "Rollover", a service which was exclusive to the "Nation" plans. AT&T also launched video share in 2007, in which a mobile caller can stream live video from one phone to another over the 3g network with video share capable phones. This allows one mobile phone user to view anothers view through the mobile phone in real time.

A large number of AT&T Mobility employees are unionized, belonging to the Communication Workers of America. The CWA represented roughly 15,000 of the previous 20,000 formerly AT&T Wireless employees as of early 2006. As of the end of 2007, the CWA website claims roughly 40,000 workers of AT&T Mobility are represented by the union.