f the structure of the relevant market before relying on network economic effects to justify regulatory intervention and that the presence of competition is likely to mitigate or eliminate any anticompetitive outcomes. For reasons introduced in the foregoing discussion on natural monopoly and discussed at greater length in Chapters 9 and 10, telecommunications networks are not likely to be sufficiently concentrated to implicate the types of market failure identified by the theoretical models. The economic literature further indicates that private ordering may well prove quite robust in solving any economic problems created by network economic effects. One major reason is that with respect to telecommunications networks, the potential network externalities are direct network externalities, in that they necessarily arise through direct connections to a physical network that can be owned (Katz and Shapiro 1985; Farrell and Saloner 1985). Thus, even though individual users may not be in a position to internalize all of the benefits created by their network adoption decisions, the network owner will almost certainly be in a position to do SO. The existence of a single network owner allows the problems associated with this type of externality to be solved through the same mechanism used to solve externality problems that arise in other contexts, that is, by placing property in the hands of a single owner and protecting it with well-defined property rights. Any benefits created by network participation can thus be internalized and allocated through the direct interaction between the network owner and network users (Liebowitz and Margolis 1994, 1995; Spulber 2008a). 23 Reliance on unitary ownership of a network to internalize any network exter- nalities that may exist does not necessarily mean that competition cannot emerge. In many cases, a network need not occupy the entire market to realize all of the 23 Indirect network externalities, in contrast, involve instances that do not involve a direct physical connection. In