PBX Networks Private Telephone Networks

138 Communication Networks Copyright © 2005 PragSoft Figure 10.16 A corporate network. Melbourne London New York PBX PBX PBX International Telephone Network Trunks Leased Lines Central Office Exchange

10.4.3. Intelligent Networks

SS7 opens the scope for user-defined procedures for the way calls are handled. This leads to the concept of Intelligent Networks IN. A conceptual view of an intelligent network is shown in Figure 10.Error Bookmark not defined.. The various components in the diagram are explained below.. Network access is facilitated through a set of Service Switching Points SSPs. The signaling link between the switches is controlled through a set of Signaling Transfer Points STPs. A Service Control Point SCP is in charge of dictating how calls should be handled and routed. For its operation, the SCP uses a service database which contains service profile definitions provided by the customer. Service profiles use a number of network-provided parameters e.g., time and date of the call, origin of the call, network-related conditions to determine how to handle calls. An Support Management System SMS provides network management and customer control capabilities. Figure 10.17 An intelligent network. SSP SSP SSP STP SCP STP STP SMS IN applications include: Call Management Services CMS, Customer Local Area Signaling Service CLASS, Personal Communications Service PCS, Centrex, Automatic Calling Card Service ACCS, and basic and enhanced 800 service. The 800 or 008 service is available in many countries. A typical 800 www.pragsoft.com Chapter 10: Telephone Networks 139 customer is an organization with numerous outlets throughout the country e.g., a fastfood chain. The service is characterized by a single number with the 800 prefix which, when dialed from anywhere in the country, is redirected to the SCP for handling. A typical service profile would use the origin of the call to direct it to the nearest outlet.

10.5. Further Reading

Martin 1988, Tanenbaum 1989, Black 1989, and Stallings 1991 provide highly readable introductory descriptions of telephone networks. Detailed descriptions of telecommunication concepts protocols can be found in Schwartz 1987, Freeman 1989, Martin 1990, Bellamy 1991, Spragins et al 1991, Van Duuren et al 1992, Heldman 1993, and Heldman 1994. Modarressi and Skoog 1990 and Jabbari 1991 describes SS7 and its use for ISDN and intelligent networks. Bush and Parsosns 1992 provide a readable account of PBX systems.