에이티앤티(AT&T) - 블랙베리폰

A national monopoly

In 1913, after vacuum-tube inventor Lee De Forest began to suffer financial difficulties, AT&T bought De Forest's vacuum-tube patents for the bargain price of $50,000 ($1.1 million in 2009 dollars). In particular, AT&T acquired ownership of the 'Audion', the first triode (three-element) vacuum tube, which greatly amplified telephone signals. The patent increased AT&T's control over the manufacture and distribution of long-distance telephone services, and allowed the Bell System to build the United States's first coast-to coast telephone line. Thanks to the pressures of World War I, AT&T and RCA owned all useful patents on vacuum tubes. RCA staked a position in wireless communication; AT&T pursued the use of tubes in telephone amplifiers. Some patent allies and partners in RCA were angered when the two companies' research on tubes began to overlap, and there were many patent disputes.
From http://en.wikipedia.org/wiki/American_Telephone_and_Telegraph