ers may have to maintain excess capacity to guard against this degradation in service, which in turn causes an inefficient increase in network cost. The impact of wholesale access is rendered ambiguous by the fact that the impact on demand depends on two prices (i.e., wholesale and retail prices). If demand increases, wholesale access creates problems that are quite similar to retail access. A demand decrease would leave the network owner with an inefficiently high level of excess capacity and can affect the decision whether to reduce costs by deploying traffic-aggregating technologies. The Coasian theory we introduce reveals that wholesale access also has the inevitable effect of externalizing retail merchant activities that would be more efficiently performed within the boundary of the firm. Interconnection access also has an ambiguous impact on demand. Although the diversion of some traffic off network lowers demand, the ability to access more customers can give rise to network economic effects that increase demand. This gives rise to the problems of network configuration discussed above, with some added twists. Unlike retail and wholesale access, interconnection access introduces new traffic flows into the core of the network, although such traffic is likely to be introduced at a major node. In addition, interconnection access creates transaction costs by requiring network owners to create new interfaces, as well as systems to monitor and bill traffic at those interfaces. It also has the effect of placing some of the information needed for network planning outside the network owner's control. Most interestingly, the problems addressed by interconnection access are, as a general matter, typically solved by competition, because the literature recognizes that the equilibrium in a market with five equal-sized players is one in which all of those players interconnect voluntarily. Platform access also has an ambiguous impact on demand, albeit for somewhat different reasons. On one hand, the increase in the number o