Centrex services. Development of the Centrex market. References. 48 Personal communications networks 36 Call Management Introduction. History. PCN definition. Overview of the PCN net- Introduction. Why call management? Special needs. Call account- work. Call set up. Planning a PCN. Mobility. Radio channel coding. ing. System interfaces. Call management trends. References. PCN base station design. Microcells. Bibliography. 37 Voice processing 49 Cordless telecommunications The voice processing market. Anatomy of a voice processing sys- Introduction. Digital technology. CT2/CAI digital specification. tem. Future directions. Bibliography. DECT digital specification. References. 38 Electronic data interchange 50 Line of sight radio systems Fundamentals. EDI in the messaging marketplace. Messaging Microwave system path design considerations. Short haul and mil- standards. Technical infrastructure. Internal topologies. X.500 di- limetre path design. Digital and analogue microwave systems. Sys- rectory services. Security. Global VAN topologies. Future trends. tem specifications and equipment design. 39 Modems 51 Communication satellite and systems Introduction. Principles of operation. Modem standards. Types of modem. Typical modem features. Applications. References. Background. International regulations. Spacecraft technology. The communication chain. Applications. Satellite systems. Future de- velopments. Acknowledgements. References. Bibliography. 40 Multiplexers Introduction. Time Division Multiplexers. Statistical time division multiplexing. High order multiplexing. Multiplexing and packet 52 Point to multipoint urban and rural radio switching. X.25 and OSI. Physical layer standards. Multiplexers in Introduction. Urban multipoint systems. Rural multipoint systems. communications networks. The future of multiplexing. Economics of urban and rural systems. References. 41 Asynchronous Transfer Mode 53 Fibre optic communications Overview and content. History. ATM: Basic principles. Standards Principles of light transmis