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 also the second largest provider of mobile telephone services and the largest provider of fixed telephone services in the United States. AT&T Inc. began its history as Southwestern Bell Telephone Company, which was a subsidiary of the Bell Telephone Company founded by Alexander Graham Bell in 1880. Bell Telephone Company evolved into American Telephone and Telegraph Company in 1885 which had since rebranded to AT&T Corporation. Following the 1982 United States v. AT&T antitrust lawsuit, this resulted in the divestiture of AT&T Corp.'s ("Ma Bell") subsidiaries or Regional Bell Operating Companies ("Baby Bells"), resulting in several independent companies including Southwestern Bell Corporation. Southwestern Bell changed its name to SBC Communications Inc. in 1995. In 2005, SBC purchased former parent AT&T Corporation and took on its branding, with the merged entity naming itself AT&T Inc. and using the iconic AT&T logo and stock-trading symbol. In 2006, AT&T Inc. acquired BellSouth, the last independent Baby Bell, making their formerly joint venture Cingular Wireless (which had acquired AT&T Wireless in 2004) wholly owned and rebranding it to AT&T Mobility. The current AT&T Inc. reconstitutes much of the former Bell System and includes ten of the original 22 Bell Operating Companies, along with the original long distance division.