Book excerpt: Telecommunications Demand in Theory and Practice, which builds upon the author's seminal 1980 book, Telecommunications Demand: A Review and Critique, provides comprehensive analyses of the determinants and structure of telecommunications demands in the United States and Canada. Theory and empirical application receive equal emphasis with a heavy focus on the developments and econometric research since the divestiture of AT&T in 1984. For the first time, a detailed theoretical analysis of business telecommunications demand on subscriber and usage consumption externalities is presented. Telecommunications Demand in Theory and Practice is without peer in the documentation and analysis of price elasticities of demand for telecommunications services. This new book also includes a comprehensive bibliography with over 500 entries related to telecommunications demand and pricing. Telecommunications Demand will appeal to both academic and consulting economists, telecommunications industry analysts and regulators, and to teachers of courses in applied econometrics and regulated industries.