AT&T can trace its origin back to the original Bell Telephone Company founded by Alexander Graham Bell after his invention of the telephone. One of that company's subsidiaries was the American Telephone and Telegraph Company (AT&T), established in 1885, which acquired the Bell Company on December 31, 1899 for legal reasons, leaving AT&T as the main company. AT&T established a network of subsidiaries in the United States and Canada that held a government-authorized phone service monopoly, formalized with the Kingsbury Commitment, throughout most of the twentieth century. This monopoly was known as the Bell System, and during this period, AT&T was also known by the nickname Ma Bell. For periods of time, the former AT&T was the world's largest phone company.
Stanley Yelnats I had apparently done some business with them, as when his stolen chest was recovered in 2003 by Stanley Yelnats IV and Zero (Hector Zeroni), it was opened by Stanley Yelnats III, and as they inspected the stock forms within the chest, as well as a pile of gold treasures. Stanley Yelnats II held up a document and said, "AT&T!" By that time, the AT&T stock had most likely gone into the millions.