From The Naked Consumer, by Erik Larson:
In 1988, Sprint began trading the names of its more than six million customers. Anyone who rented this list could select customers who were female, who made international calls, or who traveled a lot. The company tracked customers' travels by their use of Sprints "Fon Card," a telephone credit card designed to be used on the road. A Sprint executive told me the company began offering the list in order to trade it for lists owned by other companies.
Phone companies gather personal data from customers in other ways as well. MCI's Customer First program gives rebates and free services to encourage customers to call in and talk with MCI representatives every once in a while. Representative will then ask one or two more questions. For example, "Do you travel much?" "Do you have children in college?" This information them to helps them to relate how particular services meet the customer's particular circumstances.
1-800 and 1-900 phone numbers allow companies to gather data on anyone who calls up. If you call 1-900-WEATHER, for example, that information will be known by not only your long distance provider but American Express and the Weather Channel, which sponsor of the service. Regular phone numbers can do the same with caller ID. Aided by databases, companies can match phone numbers with names, address and other data.
