Switching to VoIP

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

VoIP or IP Telephony

|

19

On the WWW, web sites are hosted using software like Apache, a web server. This

software communicates with the endpoints (the browsers) in order to facilitate user

interaction with the application (web sites).

This model works much the same with Voice over IP. In a VoIP network, specialized

servers, which we’ll call VoIP servers for now, communicate with the IP or tradi-

tional phones (endpoints) in order to facilitate calling (the application).

VoIP Servers

VoIP servers, which are software-based devices that direct or participate in Voice

over IP data conversations in order to facilitate calling and other VoIP applications,

are usually connected to the network using Ethernet. An ATA is itself a highly spe-

cialized VoIP server and so is a VoIP-enabled voice mail system.

Carrier-class users of VoIP might have reasons to connect VoIP servers to a different

type of data link, such as ATM (asynchronous transfer mode), but most enterprise

implementers will use Ethernet.

VoIP servers fulfill many telephony roles:

• Call switching and connection management, such as a traditional PBX. A VoIP

server in this role is usually called a softPBX.

• Call recording and autoattendant functions, such as a traditional voice mail

system.

• Call conferencing, such as a traditional teleconferencing ...