bliography. switching. Digital switching. Stored program control. Operational security. Bibliography. 23 Safety and EMC Introduction. Safety. Basic elements of telecom safety. Classical 32 Telephone exchanges safety standards. Telecom safety considerations. EN41003. Choice Introduction. TXE analogue exchanges. The TXE2 system. The of relevant safety requirements. Documentation. Electromagnetic TXE4 system. System 12 overview. System 12 architecture. System compatibility. EMC legislation and standards. Interference coupling 12 operation and maintenance (O&M). The AXE system concept. mechanisms. Circuit design and layout. Shielding. Filtering. Cables AXE implementation. AXE applications and features. DMS system. and connectors. References. The DMS switching network. DMS Peripheral Module (PM). Contents DMS-Core. DMS-Bus. DMS software. DMS-Link. DMS OA&M. 45 Radio paging Further evolution with DMS. Introduction. Markets. Frequency allocations. Paging receiver types. On site paging. Large on site systems. Wide area paging. 33 Structured cabling systems and voice Paging receiver design. Private wide area paging. Pan- European distribution frames systems. Indirect satellite paging. Bibliography. Introduction. Structured cabling. System components. Network to- pology. Services. System performance. Testing. Voice distribution 46 PMR and trunked radio systems frames. Computer aided cable layout. References. Appendix. Private Mobile Radio. PMR systems. Trunked mobile radio. Band III. The use of troposcatter. Transmission standards. Analogue sig- 34 PABX and key systems nalling. Data transmission. Applications. Appendix. References. Purpose of key systems and PABXs. PABX architecture. Trunk circuits. Private networking. Line circuits. Control and administra- tion. Data transmission. Cordless PABX and key systems. 47 Cellular radio systems Introduction. Principles of operation. Radio planning. Overview of 35 Centrex systems. Detailed description of GSM. Services. Future develop- ments. Conclusions. References. Introduction. 