Overview

To deal with voice communications requirements, the network designer will require a basic understanding of telephone system components and design principles. The most ill considered phrase a data network designer may utter with regard to voice support is:

Voice is just another application on my data network;

or even worse

There s nothing to know about voice.

Rest assured, there is plenty to know, and if that is the attitude that engineers are taking into the design process, they are in for a rude awakening. One of the fundamental difficulties in learning about the design and implementation of enterprise voice communication networks is that there are few if any decent texts written on the subject. Those that do exist focus primarily on the public telephone network rather than business telephone systems. Further, much of what is written deals with the history of telephone technology. How much background does the reader need on a technology that will soon be abandoned?

In this chapter we will provide some of that necessary enterprise voice background. First we will look at the service configurations used for business telephone services, and where VoIP-based telephone systems and services will fit. We will also look at some of the features of a PBX system that can be used to assist in the design and operation of an IP telephone solution. Finally, we will describe the basics of telephone traffic engineering. This is the process we use to determine how many channels or trunks will be needed to...