Chapter 6. Replacing the Voice Circuit with VoIP

In circuit-switched voice networks, every time a call is placed, the network establishes a dedicated pathway from the calling endpoint through the network to the receiving endpoint. This pathway is called a loop , and it always uses the same amount of network resources (bandwidth) for the duration of the call, even if nobody is speaking. Fortunately, VoIP provides a way of leveraging packet-switched networks in order to make more economic use of available bandwidth.

This chapter describes the software and hardware elements of the voice loop as it exists in Voice over IP so you can get the most out of it. Indeed, a VoIP admin can do more to improve the quality and economics of his network by "tweaking the loop" than he can by fiddling with any other aspect of the network.