rivate line rates in that era were not primarily based on cost. While TELPAK rates were designed to track the costs of a private microwave network, rates in general were at best fatuous, based on the historical "value of service" concept. Private lines were, after all, a threat to long distance revenue: A corporation could install a tie line between two of its sites [16] and thus make calls at a fixed monthly cost, rather than pay per call. MCI's threat to offer lower The Rebirth of Competition leased-line rates was therefore not limited to AT&T's existing private line base but potentially impacted toll revenues as well. Although MCI began in the Midwest, it rapidly expanded its network. And with competition now allowed, other so-called specialized common carriers (SCCs) received authorization. A wave of investment began; building a nation- wide long distance network, even using the analog microwave radio systems of the day, was not cheap. Probably the most important of the other new SCCs was the Southern Pacific Communications Company (SPCC). The Southern Pacific was one of the country's most extensive railroad networks, and like most of its competitors, it owned a private telecommunications network as well, pri- marily built using microwave towers along its rights-of-way. Another new tele- communications company, Datran, was authorized in 1969; it built the first microwave network aimed at providing data communications more efficiently than existing analog networks. Owned by Dallas millionaire Sam Wyly's Uni- versity Computing Corp., Datran built its own facilities from Houston to Chi- cago [17]. But Datran failed in 1976, its backbone was added to SPCC's network, which later adopted the Sprint brand name and was spun off from the railroad. Even in those early days of competition, bankruptcy assets were a major tool for growth. Nonetheless, AT&T could not take lightly the threat to its own leased-line business, especially the highly profitable long-haul sector. Thus the 1970s saw a series of rate restructurings