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 3: Linux as a PBX

Other Free Telephony Software

Other open source software, including the SIP Express Router, Open H.323 (cov-

ered further in Chapter 7), VOCAL, and ReSIProcate, offer task-specific, developer-

oriented tools that can help you learn Voice over IP, too. But Asterisk is currently the

most well-rounded and mature open source IP telephony system available. That’s

why it’s been chosen to illustrate many of the examples used in this book.

Asterisk’s Requirements

Asterisk is distributed like most open-source software—you download the source

code and compile it yourself. Though Asterisk will run on FreeBSD, Solaris, and Mac

OS X, it’s easiest to compile using Linux.

Asterisk can run on many flavors of Linux, as long as the kernel version is 2.4.x or

2.6.x. Red Hat Linux 7.3, 8, and 9, which use these kernel versions, are all capable

of running Asterisk, and this chapter assumes Red Hat Linux Version 9 unless

noted. (Once Asterisk is compiled and installed, its VoIP uses are identical regard-

less of platform.) When installing Linux, be sure to include the kernel sources,

Bison, and OpenSSL packages, which are all required by Asterisk. Most distribu-

tions include a copy of each, and almost all distributions are available for download

from http://www.linuxiso.org.

If ...