This handbook delivers a complete and practical overview of the fundamentals of today's telecommunications networks and the future prospects for next generation networks (NGN). It deals not only with the technology and services intrinsic to networks, but also the regulatory, social, and business environments within which they must develop and function. The very clear and concise text, supplemented by many color illustrations and embedded into a functional four-color layout, make the handbook suitable for self-study as well as for quick reference. The intended audience includes professionals and students in electrical engineering, computer science, business, and economics. Even readers with a more general interest in high technology and the development of the information society can benefit from the easily accessible wealth of information. Many industrial experts contributed to this work, including many from Cisco and France Telecom.