Step 1 : Introduction to the question "What U.S. monopoly was broken into seven regional companies in 1984?"
...For much of the 20th century, AT&T dominated U.S. telephone service through its Bell System, controlling most of the nation's local and long-distance telephone network. After a lengthy federal antitrust case, AT&T agreed to break up its vast telecommunications empire. On January 1, 1984, the Bell System's local operations were divided into seven independent regional companies, commonly known as the "Baby Bells." AT&T retained its long-distance business and Bell Labs, while the breakup brought greater competition to the industry.