Although there is an extensive literature on many aspects of telecommunication technology, comparatively little has been published on the functioning and planning of complete telecommunication networks. The first edition of this book was intended to help fill that gap and this new edition has been thoroughly revised and includes much new material. The book is intended both to provide the young engineer with a general knowledge of telecommunications and to give the experienced specialist a deeper understanding of his/her own work against the background of the complete telecommunication network. The book evolved from IEE vacation schools at Aston University, and the chapters are mainly based on teaching contributions made by the authors at these schools.