AT&T — originally American Telephone & Telegraph — is headquartered in Dallas, Texas. The largest iPhone, iPad in the United States, AT&T is the nation's second-largest wireless carrier, behind Verizon.

AT&T's lineage runs directly back to the original Bell Telephone Company founded by Alexander Graham Bell. American Telephone & Telegraph — AT&T — was originally established in 1885.

While AT&T faced some competition in the early days, its ascendancy was all but certain by the early part of the 20th century. AT&T entered an arrangement with the United States government that virtually assured it would have a monopoly on telephone service for the U.S. market throughout most of the 20th century,

In 1984 U.S. regulators dissolved AT&T's monopoly, turning "Ma Bell" into regional operations (known as "Baby Bells") and allowing for more competition in the long distance market. Southwestern Bell was one of these. The company eventually purchased that AT&T name and brand; today's AT&T is an outgrowth of that.

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