1.1 Overview

Voice over Internet Protocol (VoIP), in particular, and Voice over Packet (VoP), in general, have been advocated and studied since the late-1970s. The reality is, however, that until the late 1990s, voice- and video-over-packet networks have been mostly used for pre-stored kinds of media solutions, namely, for oneway download of sound files or video files that were played in nonreal time at the user's personal computer, or at most, for a simplex transmission path with a relatively large intrinsic delay, such as Internet radio. At this juncture, however, there is a discernible movement afoot in the industry to affect the transition to a converged, fully multimedia-enabled, real-time packet-based communication infrastructure for both enterprise networks and for carriers network environments in support of commercial-grade real-time voice, commercial-grade video, and commercial-grade Video-On-Demand (VOD) services. These converged networks will allow voice, video, data, and images to be delivered anywhere in the world, at any time, and with any kind of user's communication device and network access service [MIN199801], [MIN199802], [MIN200201], [MIN200202].

It was the advent of Digital Signal Processing (DSP) technology for voice and video compression in the late 1980s and early 1990s that gave multimedia-over-packet services the impetus they needed to enter the mainstream. Commercial-grade VoIP technologies and services started to appear in the early 2000s in First-Generation (1G) networks. A lot has transpired since then; enterprise networks, cellular carriers, Voice-over-Cable (VoCable) carriers, "triple-play" carriers, "pure-play VoIP carriers", and even traditional voice carriers are all moving rather aggressively to...