Breakup of the Bell System

The Bell System held a virtual monopoly over telephone infrastructure in the United States from around the early 20th century until January 8, 1982. It consisted of the parent American Telephone & Telegraph Company (AT&T), which directly provided long-distance service, while local service was provided by 24 local Bell Operating Companies, which were owned whole or in part by AT&T, while its manufacturing subsidiary Western Electric produced almost all of its equipment, which was largely designed at the research and development subsidiary Bell Labs.

Source: Wikipedia — Breakup of the Bell System (CC BY-SA 4.0)