Chapter 3 of Voice over IP First-Step by Kevin Wallace describes how VoIP can compete with the reliability of traditional PBX systems, explains how to replace PBX-to-PBX connections with a VoIP network, identifies router interfaces used for connecting various analog devices (I.E., phones and fax machines) and describes how voice-enabled routers connect to digital circuits (I.E., T1 and E1 circuits).
(Reproduced from the book Voice over IP First-Step, ISBN 1587201569,Copyright © 2005, Cisco Systems, Inc. Reproduced by permission of Pearson Education, Inc., 800 East 96th Street, Indianapolis, IN 46240. Written permission from Pearson Education, Inc. is required for all other uses. Visit www.ciscopress.com for a detailed description and to learn how to purchase this title.)
This was first published in March 2006