This text covers the concepts, techniques and systems of digital communications switching and transmission. Suitable for any first course at student or practitioner level, it provides a largely descriptive treatment of theory and practice, particularly of the design and operational thinking required to establish a real system. Illustrative examples are taken from a wide range of those available. The subject matter ranges over basic switching techniques and transmission, PCM and coding, practical digital exchanges and control, signalling systems and digital and integrated networks. This edition contains an additional new final chapter explaining applications in ISDN/fibre optic links/network management. It is aimed at the level of the telecommunications engineer, as distinct from the computer engineer.