uts it uses. E. Distinguishing among Different Types of Access to Networks Applying graph theory and transaction costs to networks provides a basis for a more specific definition of access. Access in our framework refers to economic transactions between network firms and their customers, partners, and other network firms. Access is the critical economic mechanism for allocating network services and organizing network industries. Our framework makes it possible to distinguish among five different types of access, each with its own distinct economic and legal implications. (1) Retail access refers to transactions between network firms and retail customers. (2) Wholesale access denotes transactions between network firms and resellers. (3) Interconnection access refers to transactions between network firms for origination, termination, and transit of transmissions. (4) Platform access is the set of transactions between network firms and suppliers of complementary services, such as programming on cable networks or Internet content providers. (5) Unbundled access includes transactions between network firms for leasing network elements such as lines and switches. Distinguishing among different types of access in this manner provides a clearer understanding of how compelling access can have unintended effects. For example, the manner in which regulators have implemented access regimes has resulted in major distortions in market transactions for access. In addition, compelled access potentially affects the design and planning of networks, resulting in inefficient usage of existing networks and inefficient investment in network facilities over the long term. The combination of these regulatory effects further alters the tradeoffbetween market transactions and the internalization of particular business activities within the boundaries of the network. Networks in Telecommunications F. Toward a Market-Based Approach to Access Prices In addition, our analysis offers a powerful critique of regulators' current tendency to implem