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 terms of number of subscribers) in the United States, ahead of Verizon Wireless. AT&T Mobility has approximately 72.9 million subscribers as of the third quarter 2008.

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 re-branded 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.

In January 2007, Cingular confirmed it would itself rebrand under the AT&T moniker. The corporate name change occurred immediately, although, for regulatory and brand-awareness reasons, both brands were used in the wireless unit’s signage and advertising during a transition period.[5] The transition concluded 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 another’s camera through the mobile phone in real time.

A large number of AT&T Mobility employees are unionized, belonging to the Communications Workers of America. The CWA represented roughly 15,000 of the previous 20,000 formerly AT&T Wireless employees as of early 2006.[6] As of the end of 2007, the CWA website claims roughly 40,000 workers of AT&T Mobility are represented by the union.

Cingular Wireless LLC was founded in 2000 as a joint venture of SBC Communications and BellSouth. The joint venture created the nation’s second largest carrier. Cingular grew out of a conglomeration of more than 100 companies, with 12 well-known regional companies with Bell roots. The 12 companies included:

* 3 companies spun off from Advanced Mobile Phone Service, Inc.
o Ameritech Mobile Communications, LLC
o BellSouth Mobility, LLC
o Southwestern Bell Mobile Systems, Inc.
* BellSouth Mobility DCS, Inc.
* BellSouth Wireless Data, LLC
* Pacific Bell Wireless, LLC
* Pacific Bell Wireless Northwest, LLC
* SBC Wireless, LLC
* SNET Mobility, LLC
* Southwestern Bell Wireless, Inc.

Also included were:

* some Cellular One markets
* Houston Cellular.

Cingular’s lineage can be traced back to Advanced Mobile Phone Service, which was a subsidiary of AT&T created in 1978 to provide cellular service nationwide. AMPS, Inc. was divided among the Regional Bell Operating Companies as part of the Bell System divestiture.

With the exception of Pacific Bell and BellSouth Mobility DCS, the digital network consisted of D-AMPS technology. The Pacific Bell and BellSouth Mobility DCS networks used GSM technology on the PCS frequency band (1900 MHz).

In October 2007, AT&T’s president and chief executive officer Stan Sigman announced his retirement. Ralph de la Vega, group president-Regional Telecom & Entertainment, was named as president and CEO, AT&T Mobility.

In California, Nevada, Northern New Jersey and New York City, Cingular and T-Mobile USA maintained and shared a GSM-1900 network prior to the acquisition of AT&T Wireless, through a joint venture known as GSM Facilities. The network sharing agreement allowed Cingular to offer local service in northern New Jersey and New York City and T-Mobile to offer service in California and Nevada. On May 25, 2004, Cingular and T-Mobile USA announced their intention to dissolve the agreement contingent on Cingular’s successful acquisition of AT&T Wireless, the Cingular network was transferred to T-Mobile, with Cingular continuing work on the GSM facilities at AT&T Wireless sites.

Network coverage
An AT&T Mobility Device Support Center in Las Vegas, Nevada.

AT&T Mobility was formed through mergers and acquisitions, and as a result of these — as well as the rapid technological change in the wireless industry — AT&T Mobility operates wireless networks using many different wireless communication standards. The most widely used of these technologies is called Global System for Mobile Communications, or GSM. On top of its GSM network, AT&T Mobility operates a data network called GPRS (General Packet Radio Service) and an upgrade for faster speeds called EDGE (Enhanced Data rates for GSM Evolution). AT&T Mobility offers Push to talk (PTT) service using network technology from Kodiak Networks.

AT&T Mobility (formerly Cingular) formerly supported legacy D-AMPS/TDMA, and analog networks; however, in March 2006 they announced that these networks would be shut down by February 2008. As part of this effort, AT&T Mobility will charge a $4.99 monthly fee to those customers who still use D-AMPS-based phones. As of March 31, 2007 Cingular (now AT&T Mobility) no longer supported the TDMA technology for its GoPhone (pre-paid) customers. All GoPhone customers were forced to migrate to the newer GSM technology.

As of February 18, 2008, AT&T Mobility has officially ended service on their AMPS and TDMA network, except for in areas previously operated by Dobson Communications. The Dobson AMPS and TDMA network was shut down March 1, 2008.

Former networks also include various paging services and the Cingular Interactive division, which became Velocita Wireless which was purchased by Sprint Nextel.[16]

In 2002, Cingular (now AT&T Mobility) began an initiative called "Project Genesis" that involved a GSM/GPRS overlay of the entire wireless network. Project Genesis was completed by the end of 2004.

AT&T Mobility has launched a high-speed network known as "BroadbandConnect", based on UMTS and High-Speed Downlink Packet Access (HSDPA), to counter Verizon Wireless, Alltel and Sprint’s EV-DO networks. UMTS service was launched on December 6, 2005 in Seattle, Portland, San Francisco, Salt Lake City, San Jose, San Diego, Las Vegas, Phoenix, Puerto Rico, Austin, Houston, Dallas, Detroit, Chicago, Boston, Baltimore and Washington D.C. Cingular expected to launch UMTS in all major metropolitan markets by the end of 2006. AT&T Mobility is currently working on upgrading its 3G network to HSUPA which will replace the current UMTS upload method. New PC cards featuring HSUPA will be released in October and November by AT&T.

Acquisition of Dobson Communications
Transition banner used for Dobson/AT&T transition
Dobson Cellular Logo
Cellular One logo used by Dobson until acquisition by AT&T in November 2007

On November 15, 2007 AT&T completed its acquisition of Dobson Communications. Dobson marketed the Cellular One brand in rural and suburban locations in various areas of the United States, including Alaska. AT&T bought Dobson for $13 per share, as well as assuming the regional carrier’s debt, which will cost the nation’s largest carrier about $5.1 billion total. The U.S. Justice Department had ordered AT&T Inc. to sell assets in five U.S. states to complete its $2.8 billion Dobson Communications Corp. takeover. The department ordered AT&T to divest certain cell-phone assets in Kentucky, Oklahoma, Missouri, Pennsylvania and Texas where AT&T and Dobson are most competitive. AT&T is the largest U.S. cell-phone provider, with more than 65.7 million subscribers in 50 states. Dobson’s Cellular One was the ninth largest, with 1.7 million subscribers in 17 states. Dobson had been an AT&T roaming partner since 1990, and the acquisition is expected to bring growth to Dobson’s current markets. The purchase allowed AT&T to operate in the more rural areas of the United States including Alaska & West Virginia.