AT&T Inc. is an American multinational conglomerate holding company, headquartered at Whitacre Tower in downtown Dallas, Texas. AT&T is the world's largest telecommunications company. AT&T is the second largest provider of mobile telephone services and the largest provider of fixed telephone services in the United States, and also provides broadband subscription television services through Uverse Tv service, and DirecTV threw the satellite subscription television, combined with AT&T's legacy U-verse service, this also makes AT&T the largest pay television operator. AT&T is the second-largest company in Texas, behind ExxonMobil. , AT&T is the 12th largest company in the world (non-oil and overall) as measured by a composite of revenues, profits, assets and market valuation. AT&T is the largest telecommunications company in the world by revenue. , it is also the 21st-largest mobile telecom operator in the world, with 138.8 million mobile customers. AT&T was ranked at #4 on the 2017 rankings of the world's most valuable brands published by Brand Finance.