Baby Bell

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of the seven regional telephone companies created in 1984 when AT&T was ordered to divest itself of its local telephone service operations.

Wiktionary

1. n. US, informal Any of the Regional Bell Operating Companies resulting from the division of AT&T Corporation into a number of smaller companies in the 1980s as part of an antitrust agreement.