Wireless technology is still revolutionizing the way people communicate by phone, but already gathering momentum is the next revolution in personal communications technology--Internet-based telephony. Packet signaling and switching are core technologies for Internet-based telephone communications, and this reference is an in-depth treatment of the essential principles and cutting-edge architectures of these technologies. It is especially valuable for telecom engineers whose companies are making the transition from current circuit-based technology to packet-based. To successfully guide this transition, telecom engineers need a solid working knowledge of packet-based protocols used for switching and signaling. This book provides this knowledge plus enables engineers to evalute the relative merits of competing protocols. Professionals are bracing for the challenges of the Internet telephony revolution, and this book enables them to meet these challenges head-on.