Switching to VoIP

This is the Title of the Book, eMatter Edition

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

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Chapter 2: Voice over Data: Many Conversations, One Network

circuit-switched voice network has hard capacity limits, around which levels of ser-

vice tolerance can be guaranteed easily. Certain broadcast audio applications, like

overhead paging, can be difficult with VoIP, too.

The gains VoIP brings to the table far exceed the few difficulties it imposes, though.

There’s nothing that old PBX can do that a VoIP telephony system can’t, even if VoIP

makes a few things tougher.

One thing VoIP makes easier is physical provisioning. While a PBX requires a net-

work of electrical, usually copper wire, loops, VoIP requires an IP network. Since IP

networks are a staple of every modern business, the logistics of building a network

for voice is largely simplified because the required physical elements are already in

place for other common business applications: databases, messaging, Internet access,

and so on. VoIP is carried on the network the same way those are.

If you’re an Internet user (and who isn’t these days), then you know TCP/IP is the

core protocol that defines the architecture of the Internet. In most organizations, and

even in many homes, a TCP/IP local area network is an important interpersonal

communications tool, used for email, web surfing, and instant messaging. When

VoIP