에이티앤티(AT&T) - giants

A national monopoly

In the 1980s, after some consumers began buying phones from other manufacturers anyway, AT&T changed its policy by selling customers the phone's housing, retaining ownership of the mechanical components — which still required paying AT&T a monthly leasing fee.

For most of the 20th century, AT&T subsidiary AT&T Long Lines thus enjoyed a near-total monopoly on long distance telephone service in the United States. AT&T also controlled 22 Bell Operating Companies which provided local telephone service to most of the United States. While there were many "independent telephone companies", General Telephone being the most significant, the Bell System was far larger than all the others, and widely considered a monopoly itself.
From http://en.wikipedia.org/wiki/American_Telephone_and_Telegraph