AT&T Information Systems (ATTIS), originally known as American Bell, was the fully separate subsidiary of American Telephone & Telegraph Company (AT&T) which focused on computer technology ventures and telephone sales, and other unregulated business. It was one of the three core units of AT&T formed after the breakup of the Bell System. As a twenty-five percent owner, AT&T Information Systems utilized production of Olivetti to manufacture their AT&T PC 6300 series of computers. Along with the 3B series computers and the AT&T UNIX PC the PC 6300 series of computers represented a multi-faceted strategy of competing with IBM, who was the leading computer manufacturer of the time.

AT&T Corporation, commonly referred to as AT&T, an abbreviation for its former name, the American Telephone and Telegraph Company, was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies.