ngement and settled in 1885. Ma Bell and Her "Natural Monopoly, 1876-1969 Patent Protection Bell's patent granted a monopoly on the telephone for 17 years [2]. During that time, telephone service was introduced into a number of major American cities. Switchboards were set up and telephone poles erected. The American Bell Tele- phone Company grew rapidly, but telephone service was simply not available in areas the company chose not to serve. American Bell adopted a vertically inte- grated business model: Following its acquisition of Western Electric in 1881, it was both equipment manufacturer and service provider. Bell's original patent expired in 1893, at which point any number of new players entered the scene. Within the next 10 years, two million non-Bell tele- phone lines were installed across the country [3], and American Bell's market share was down to around 40%. While many of the new telephone companies served areas that Bell had ignored, others provided head-on competition in Bell Telephone's own markets. But Bell continued to collect and use a variety of pat- ents to protect its interests. One of Bell's main competitors for the manufacture of telephone gear was Kellogg Switchboard and Supply. Sometime before 1903, Bell secretly bought controlling ownership, through a trust, from a relative of the founder. Kellogg supplied many of the new competitive service providers. Bell brought a patent infringement suit against Kellogg and its customers, which Kellogg of course did not vigorously defend. This effort only ended when the secret ownership was revealed, and a lengthy court battle voided the sale as anticompetitive. Another patent was more successful at helping Bell cement its grip over the industry. Telephone wires have a limited range: A plain copper wire pair can only carry intelligible voice, between conventional telephones, for a few miles. Michael Pupin, an immigrant from what is now Serbia who taught at Columbia University in New York, filed a patent in 1899 covering the use of loading coils on tel