Public Data Networks

This is a survey of public data networks which covers all major countries. PDNs allow efficient and cost-effective telecommunication between a terminal and computer, or between computers, regardless of who owns the data terminal. The authors discuss the current state of, and forthcoming developments in, data communications using public telecommunication facilities. Apart from the classical telecommunication networks (telegraph and telephone), public data networks provide the majority of data communication services worldwide. The range of data services and user facilities has gradually expanded, the quality of services improved, and new services have appeared such as datafax, teletex, videotex, message handling and teleconferencing. The authors concentrate on PDN principles, taking account of the latest CCITT recommendations and ISO standards. Appendices and references provide detailed information for those working on PDNs at research, design and implementation level. The text explains how network digitalization and integration of networks and services have aided progress towards the integrated services digital network (ISDN). The ISDN uses advanced transmission and switching techniques to enhance the telecommunication services provided to its users.