services. In this case, connection resources do not exist as semipermanent or permanent resources (as in transmission and transport networks), but are used per call, i.e. on demand. Connection resources can, in principle, be provided by a net- work other than the teleservice network itself. Also note that, by separating con- nection control from service control, the functions represented by RAs, RMs, ATs and SWCs become part of the logical network Fixed Connection Process Control in Fig. 3.91. Public network architectures are increasingly separated into service and connec- tion handling. The connectivity systems in future networks will provide an IP serv- 3.5 Logical Network Structures ice, and its logical network structure will consist only of an IP-logical network and an ATM-CSP. An example of that is GPRS (see the case study in Sect. 4.4), which is based on IP for transporting information between the GPRS process controlling nodes in the core network. The GPRS-standard does not say anything about the transport level in the core network, but an ATM-CSP seams to be a natural choice. The Teleservice Control System in Fig. 3.91 is separated in the two components Distributed Service Process Control and Centralized Service Process Control to reflect the intelligent network (IN) concept, which is implemented in both fixed and cellular networks today. The concept "intelligent network" is somewhat mis- leading, since the name implies that it is a logical network of its own. The IN con- cept represents a strategy for distributing teleservice process control functions into functions that handle services that should be available to every service user, and functions that handle service features that need not be available to everybody. The former are implemented in the DNCP in every physical node that handles accesses, the latter can be centralized in the operator network in one or a few physical nodes. A call from or to a service user might involve using features that are implemented in the centralized part, in which case,