Each of the types of access in our classification scheme has a corresponding set of regulations. Retail access is implemented through common carrier regulations. Wholesale, interconnection, and unbundled access in telecommunications regula- tion are addressed extensively by the Telecommunications Act of 1996 and FCC regulations. Platform access is addressed by open access regulations and antitrust enforcement, including merger conditions in the cable industry. In addition, the basis for determining the rates paid for access varies considerably. In some cases, access prices are determined through private negotiations. In other cases, regulatory authorities set them pursuant to varying methodologies. 1. Retail Access Mandated retail access gives end users rights to obtain the network's services, whereas wholesale, interconnection, and unbundled access are provided to competitors. Customer access to a telecommunications network means the ability to commu- nicate with others who also have access to the network. Because retail access to a network refers to a customer's use of the network's services, which are the out- puts of the network, access means more than simply a physical connection to the Networks in Telecommunications network. The physical connection is necessary but not sufficient for access. Rather, access refers to the opportunity to benefit from the services generated by network usage. Retail access has its origins in the common law duty to serve that applies to all common carriers (Sidak and Spulber 1997a). With respect to intrastate com- munications, states typically implement retail access through public tariffs, which specify terms of service that the carrier must make available to any requesting cus- tomer. With respect to interstate communications, the Communications Act of 1934 requires carriers to provide service to any customer making a reasonable request for service (47 U.S.C. § 201 (a)). Although interstate rates were once governed by tariffs as well, following a long battle that eventually inv