Public Data Networks provide a comprehensive survey of PDNs, covering 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...