n in Long-Distance Telephone Services (Cambridge, Mass.: MIT Press, 1996); and William E. Taylor and Lester D. Taylor, "Postdivestiture Long-Distance Competition in the United States," American Economic Review: Papers and Proceedings (May 1993), pp. 185-90. 18. Large business customers can use private lines or "special access" to avoid originat- ing switched access charges, but such options are not available for incoming calls except through the use of 800 numbers. For this reason, terminating access minutes are often used as a proxy for conversation minutes. 19. FCC, Eighth Annual CMRS Competition Report (July 2003), appx. D, table 9. 20. Ibid. 21. According to the CTIA Semiannual Wireless Survey, there were 140.8 million sub- scribers at the end of 2002 and 128.4 million at the end of 2001. I therefore assume that the average subscriber level over the year was 134.6 million. The difference in minutes of use is approximately 300 a month, or 3,600 a year. Thus the total estimated increase is 484.6 billion minutes. 22. These estimates are derived from TNS data and are published in FCC, Trends in Telephone Service (May 2004), table 11.4. 23. The Bell company lines (RBOCLINES) variable is the sum of switched access lines in states in which the Bell companies have received Section 271 approval, as reported in the FCC's Statistics of Communications Common Carriers for December 31, 2001. Average wire- less minutes of use per subscriber per month (WIRELESSMIN/MO) are interpolated from semiannual reports from the CTIA. RBOCLINES was lagged to allow for time for Bell Notes to Pages 88-95 companies to develop and market long-distance service plans. The best fit was found in an equation in which RBOCLINES is lagged three months. The equation was estimated with and without a time trend. Because the wireless minutes variable (WIRELESSMIN/MO) and the time trend are collinear, the statistical significance of each is reduced substantially when both are included; therefore I use the equation without a time trend. The magnitude an