odities. The evolution to IP-based infrastructures means more shared networks. Because IP emphasizes logical over physical connections, IP makes it easier for Chapter 9 IP Services multiple carriers to coexist on a single network. This encourages cooperative shar- ing of interconnected networks, structured as anything from sales of wholesale cir- cuits to real-time capacity exchanges. It also means increased competition because there are reduced barriers to entry; new companies can enter the market without the huge fixed costs associated with traditional network models. Most of the evolution SO far has taken place in the transport and access parts of the network and in the development of IP infrastructure elements, such as gateways, softswitches, and the IP Multimedia Subsystem (which is discussed in Chapter 10, "Next-Generation Networks"). The market for next-generation IP application ser- vices is beginning to take shape, and IP-based application servers have been devel- oped to deliver actual revenue-generating services for carriers. The problem is that IP has been positioned as a magical potion that will cure everything, and the industry has suffered from too much hype and wishful think- ing. Equipment and service providers have been guilty of promoting such think- ing, claiming that their products can enable multiple new services without clearly identifying just what those new services will be. While there are indeed very good reasons to transition to IP, it is important to be realistic and pragmatic about them. The migration to IP is not without risk. In terms of the IP application services mar- ket, two key questions need to be answered: Will the quality of the real-time ser- vices over IP be good enough in the next few years to drive carriers and customers to switch? To what extent will enterprises take advantage of their existing IP infra- structure and data communications expertise to implement their own services, thus avoiding additional service provider charges? Traditional Internet applications, such