gulatory regime leaves no role for antitrust courts. Others have read Trinko more narrowly, arguing that the scope of judicial authority depends on a more nuanced assessment of the nature of the regulatory regime. Until the Court resolves this uncertainty, it remains possi- ble that courts will use the antitrust laws to compel access to telecommunications networks. The lingering possibility of antitrust enforcement in this area makes under- standing the scope of compelled access permissible after Trinko absolutely critical. The commentary on the essential facilities doctrine has generally treated access as a unitary concept without analyzing in sufficient detail how differences in the type of access can affect its costs and benefits. The Trinko opinion contains tantalizing hints suggesting how the nature of the party seeking access, the number of network elements to which access is sought, the technological complexity of the interface, and whether the access sought is already being provided to other customers can each affect the analysis. Unfortunately, the opinion merely offered these observations in passing without developing them in a systematic way. The five-part classification system introduced in Chapter 5 offers a basis for differentiating among different types of access that have fallen under the larger umbrella of the essential facilities doctrine based on the nature of the party seeking access, the portion of the network to which access is sought, and the nature of the services that the party seeking access intends to provide. This framework allows us to evaluate the effect that each form of access has on the demand for network services, the network's maximum carrying capacity, its optimal configuration, and its cost structure. At the same time, this framework underscores the impact that the differences between the forms of access can have on transaction costs, both by increasing the cost of obtaining the information needed to manage the network and by forcing the network to deviate from its natural ins