Summary: Telephone slamming--the unauthorized switching of a customer from one long-distance carrier to another--is a growing problem. The Federal Communications Commission (FCC), state regulatory agencies, and the telecommunications industry each rely on the others to be the main forces against intentional slamming. However, FCC's antislamming measures do little to protect consumers from slamming. Although representatives of state regulatory agencies and the industry view a provider's FCC tariff--a schedule of services, rates, and charges--as a key credential, FCC places no significance on the tariffs that long-distance providers must file with it before providing service. FCC accepts tariffs, but it does not review the information they contain. Thus, having a tariff on file with FCC is no guarantee of a long-distance provider's integrity or of FCC's ability to penalize a provider that slams consumers. As part of its investigation, GAO easily filed a tariff with FCC and could then slam consumers with little chance of being caught. State regulatory measures that could preclude slamming range from none in a few states to extensive in others. Industry's antislamming measures appear to be more market-driven. However, by contacting their local exchange carrier and "freezing" their choice of Primary Interexchange Carriers, or long-distance providers, consumers can effectively reduce the chance of intentional slamming. In a case study, GAO found that one individual was responsible for slamming more than 500,000 consumers. His companies billed their customers at least $20 million in long-distance charges and left at least $3.8 million in unpaid bills to industry firms, including long-distance carriers, with which they were doing business.