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Preface - Pg. xi

Preface Voice over IP (VoIP) in particular and Voice over Packet (VoP) in general have been advocated and studied since the mid 1970s. It was the advent of DSP technology for voice compression in the late 1980s and early 1990s that gave these services the impetus they needed to enter the mainstream. Commercial-grade tech- nologies and services started to appear in the 1996-7 timeframe and books on the topic started to appear in 1998, with Mr. Minoli's co-authored Delivering Voice over IP book (Wiley, April 1, 1998) being the first text on the market on this topic. A lot has transpired since then. Now, enterprise networks, cellular carriers, voice-over-cable carriers, "triple-play" carriers, "pure-play VoIP carriers," and even traditional voice carriers are all moving rather aggressively to a VoIP paradigm. A fair degree of commercial success can be acknowledged as of 2006. Small-to-medium size enterprises are using the technology to save money on trunking costs. Large-size enterprises are using the technology for mobility support and related functional enhancements, including "presence-related functions" and unified messaging. Large-size companies are also using this technology for Contact Center support, particularly for hosted ACD-capabilities and for virtual Contact Centers (where agents are distributed throughout al large geographic area.) Carriers are deploying these services to generate new revenues, stem the movement away from traditional TDM services, and enter new markets (e.g., "triple-play" applications.) However, there are two fundamental problems that currently pose a significant risk to the scalability of VoIP to a large-population base along with guaranteed "industrial-grade" service levels. The first problem is lack of de-facto intrinsic QoS in many of the IP networks deployed around the globe (both at the carrier level and