This book gives an introduction to the principles of signalling systems along with an in-depth examination of their architecture. Modern signalling systems are described in detail, including Signalling System No.7 and the Digital Subscriber Systems, while older systems are outlined in the appendices. Chapters are devoted to signalling for mobile networks, intelligent networks and private networks. Signalling interworking, the role in network management and meeting broadband requirements are also covered. Internet technologies are coming to the fore and a chapter explains some common Internet Protocols and highlights the striking similarities with telecommunications systems. The glossary and list of abbreviations cut through the maze of jargon. The book will appeal to a wide range of readership. Reading the chapters in sequence will provide a comprehensive description of signalling. Communications experts will find the chapter summaries useful in selecting appropriate text. Experts in specialised areas of signalling can use the book to expand their range of knowledge.