AT&T Inc. is an American
multinational telecommunications corporation, headquartered at
Whitacre Tower in
downtown Dallas,
Texas. AT&T is the second largest provider of
mobile telephone and the largest provider of
fixed telephone in the United States, and also provides
broadband subscription television services. AT&T is the third-largest company in Texas (the largest non-oil company, behind only
ExxonMobil and
ConocoPhillips, and also the largest Dallas company). , AT&T is the 23rd-largest company in the world as measured by a composite of revenues, profits, assets and market value, and the 16th-largest non-oil company. , it is also the
18th-largest mobile telecom operator in the world, with over 128.6 million mobile customers.