vertically inte- grate with buyers. Wholesale access is provided when the network owner finds the organizational costs of conducting retail sales greater than the market transaction costs of dealing with independent wholesalers. Unbundled access is provided when the network owner finds the organizational costs of managing particular nodes and links in the network to be greater than the transaction costs of dealing with independent operators. Platform access is provided when the network owner finds the organizational costs of managing the development and supply of complemen- tary services to be greater than the transaction costs of dealing with independent suppliers. In the case of platform access, the relative inefficiencies and reduced cre- ativity of internal provision of complementary services translate into incremental organizational costs. These issues are a special case of vertical integration, but the implications for networks need to be fully addressed. Interconnection of distinct networks can be more efficient than a unified net- work if the additional organizational costs of managing the combined networks are greater than the transaction costs associated with interconnection. The costs of managing a network also include costs associated with providing retail access and procuring services as well as facilities management. Thus, the cost savings from separate networks that are interconnected also reflect all the operating costs as well as other types of transaction costs. The costs of interconnecting diverse networks are relatively low compared to the costs of managing networks. Accordingly, the many diverse telecommunications networks, including wireline telecommunica- tions, mobile telephony, the Internet, and cable telephony, can coexist through interconnection. The efficient boundaries of firms that operate networks are an important but particular case of the boundary of the firm. Networks provide wholesale, unbun- dled, and platform access when the organizational costs of managing the network are gre