Asterisk. The Future of Telephony [Englisch] [Taschenbuch]

In typical O'Reilly fashion, this is a very readable guide for installing and administering Asterisk, the open-source solution for Voice over IP that runs on Linux. Step-by-step instructions are given, which is very necessary in a very new product that is short on documentation. There are even a few chapters that discuss basic telephony technology and others that discuss where Voice over IP has been and where it may be going in the context of open source solutions such as Asterisk, so this is not just a dry boring instruction manual. I notice that Amazon does not have the table of contents available, so I show and describe that here:
Chapter 1 "A Telephony Revolution" is just an introduction to Voice over IP and how it differs from computer integrated telephony solutions of just a few years ago.
Chapter 2 "Preparing a System for Asterisk" is about selecting server hardware, telephony hardware, different types of phones, and Linux considerations.
Chapter 3 "Installing Asterisk" tells you what packages you will need, how to obtain the source code, and how to compile, install, and update your source code.
Chapter 4 "Initial Configuration of Asterisk" is about working with interface configuration files, FXO and FXS channels and their configuration, configuring SIP, and configuring inbound and outbound connections. Debugging issues are also raised.
Chapters 5 and 6 are about dialplans. This ranges from dialplan basics and syntax to adding logic to a dialplan. Also expressions and variable manipulation as well as dialplan functions are discussed. Finally, the Asterisk database is discussed. These two chapters are what I consider to be the meatiest part of the book.
Chapter 7 "Understanding Telephony" discusses general telephony technology. Both analog and digital systems are discussed. The digital circuit-switched telephone network and packet-switched networks are explained.
Similarly, chapter 8, "Protocols for VoIP" discusses the need for VoIP protocols, the protocols themselves, codecs, the concept of quality of service and echo, and finally how Asterisk fits into VoIP.
Chapter 9 is about the Asterisk Gateway Interface and how to write scripts for it in a variety of common languages. This is very interesting material for advanced users who enjoy programming.
Chapter 10 is about advanced concepts and includes details on Festival, call detail recording, customized system prompts, and call files.
Chapter 11, the final chapter, is about the future of telephony and how Asterisk might fit into that future.
There are several useful appendices in the back of the book on VoIP channels, an application reference, an AGI reference, a section on configuration files, and finally an Asterisk command-line interface reference.

This book really isn't all that great and leaves many a stone unturned for novice and professional alike, but I'll give it three stars anyway just because you can legally download an electronic copy for free right from the "Support" section of the main Asterisk website.

If you want a book that's going to explain how to configure VoIP hardware that isn't sold by Digium, try "Switching to VoIP" and just stick to the online docs and sample config comments for Asterisk.

The few reviewers who preceded me were a little star-happy with this book, I believe, despite pointing out some serious shortcomings.

I could probably say that this is the best book currently available on Asterisk, but then again, this is almost the only book available on Asterisk...

The THREE authors produced a mere 208 pages; the remainder is in the form of appendices. And when you factor in the space consumed by scripting examples, you'll realize how you finished the book so quickly.

Some of the chapters do warrant merit. A chapter on hardware requirements for Asterisk was helpful, and those pertaining to the dialplan and AGI scripting were supported with some useful sample code. But instead of delving into important areas like SIP and interfacing with service providers, the authors chose to write too much about Free World Dialup, for example. For those seriously considering Asterisk as a business communications platform, this hobbyist approach to the subject is not amusing.

(One final complaint: O'Reilly should be ashamed for allowing so many typographical errors to make it into print.)

Asterisk needs a thoroughly written manual for the telecom professional: this is not that book. However, if you are new to Asterisk and have never done any programming, this book is still recommended, if for no other reason than it's the only other (current) option apart from online material.