Introduction in .NET framework

Paint ECC200 in .NET framework Introduction

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Although it is true that bandwidth-efficient coding schemes can reduce overall bandwidth requirements, we shall see in 9, Designing a VoIP Network, that IP and associated protocols add some overhead beyond the bandwidth of the coded voice itself Therefore, coding voice at, say, 32 Kbps, does not necessarily mean a 50 percent bandwidth reduction compared to 64 Kbps G711 coding Beware of anyone who suggests such a simple comparison The exact bandwidth saving compared to traditional telephony is dependent on a number of factors and requires some calculation These calculations are described in 9 Not only can transmission costs be reduced through the use of more efficient voice-coding schemes, but the fundamental architecture of VoIP systems lends itself to more transmission-efficient network designs Recall that traditional circuit-switching networks tend to be composed of large monolithic systems These systems lend themselves to centralized network architectures, with both call control signaling and bearer traffic being routed through the same centralized machines VoIP systems, however, are designed to be distributed Although call control signaling can be centralized in a limited number of centralized machines, the bearer traffic does not have to be routed through the same machines Rather, the bearer traffic can be routed more directly from source to destination, leading to shorter transmission distances and lower cost

IP is practically everywhere Every personal computer produced today supports IP It is used in corporate local area networks (LANs) and wide area networks (WANs), as well as in dial-up Internet access IP applications now even reside within hand-held computers and various wireless devices As a result, IP expertise is widespread and application development companies are numerous This ubiquitous presence alone makes IP a suitable choice for transporting voice, or any other digital media stream for that matter Of course, VoIP is not the only packet-based solution available to a commercial carrier In fact, Voice over Frame Relay (VoFR) and Voice over Asynchronous Transfer Mode (VoATM) are powerful alternatives One of the great disadvantages of such solutions, however, is that they do not have the same ubiquitous presence as IP Although many users currently use IP, whether they know it or not, the same cannot be said for Frame Relay or ATM IP is already at the desktop and it is hard to imagine that the same will ever apply to ATM or Frame Relay To some extent, IP at the desktop might not matter to a next-generation Telco if the main objective is just to capture market share in the longDownloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website

distance business Such a business could be easily served by other technologies besides IP To ignore IP, however, would be to decline possible opportunities offered by voice and data integration It would also limit choices and opportunities for advanced applications, and it would reduce the possible benefits from the myriad advances being made almost daily in the IP community That is not to say that ATM and Frame Relay do not have a role to play They certainly do, perhaps in the core of the network as an underlying network transport for IP, but not at the user device

It is clear from the previous descriptions that VoIP can offer cost savings, new services, and a new way of doing business, both for carriers and network operators It is also clear that voice is an important service, but not the only one Rather, it is part of a suite of services that, when packaged together, can offer exciting new capabilities All of this translates into serious revenue opportunities Although the business is currently only in its infancy and much of the revenue is yet to be seen, the future is certainly bright Figure 1-6 gives one projection of the market for Voice over Packet

Figure 1-6