The second edition of Fundamentals of Digital Switching, provides an up-to-date introduction to the principles of voice and data switching. The author is once again the editor of the volume, which consists of completely revised chapters and two entirely new contributions on communications switching architectures for business, industry, and government (PABXs), and on the integrated services digital network(ISDN). The tex commences with an overview of the fundamentals tha apply to any type of switching systems and a review of the basic concepts of circuit and packet switching. The more complex areas of architectures and networks for digital switching systems, the analog termination, digital termination, and digital signal processing, among others are then addressed. In addtion, the latest information on fast packet switching, the asynchronous transition mode, and its evolution is discussed by the inventor of packet switching, Paul Baran