A jocular name for AT&T (American Telephone and Telegraph Corporation), originally a subsidiary of the Bell Telephone Company, especially in reference to its monopoly of phone services across the United States and Canada up until 1981. (Its regional subsidiaries, which it was required to divest in 1982 as the result of an antitrust lawsuit, were known as "Baby Bells.") My dad worked for Mama Bell for nearly 40 years as an engineer. If the merger goes through, Mama Bell will once again control nearly all of the telephone operations across the entire country. There were few complaints from people working within the company, though, especially at the corporate level—Mama Bell certainly took care of her own.