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2005-09-29 - Book review: VoIP telephony with Asterisk

The book bills itself as a beginner's guide to Asterisk and Voice over IP (VoIP). Even with over 270 pages, it isn't possible to go through every single feature that Asterisk has to offer but the book does give enough information to get you started and even apply a few advanced features to your phone system. For those of you not familiar with Asterisk, VoIP, or PBX's we will need a little bit of background for you to know if this book is for you.

A PBX is an automated phone system typically used by medium to large sized companies. Common features include voicemail, personal extensions, call transfers, conferencing, call parking, and least cost routing to name a few. Think of a PBX as the modern electronic version of Lily Tomlin's operator character handling all the inbound and outbound calls automatically. Asterisk is a PBX system designed to run on flavors of Unix with the major feature components handled through software rather than custom hardware. This makes the cost of building a PBX based on Asterisk extremely affordable. VoIP technology allows the use of a number of different telephone handsets with an Asterisk server instead of being locked into a very small number of handsets that is typical of standard PBX systems. VoIP can also be used to bring telephone service into a facility over a broadband internet connection which bypasses the telephone companies.

VoIP Telephony with Asterisk goes into more detail on these concepts as well as providing examples of how Asterisk can be used in small to large corporations. The first few chapters detail different configuration scenarios and different ways that Asterisk can be connected to the telephone network (referred to as PSTN for publicly switched telephone network). The next chapters go into designing your first installation and getting Asterisk installed on a machine. The book includes two CD’s that automate much of getting Asterisk up and running along with a number of sample scripts and configuration files to help get your started.

The rest of the book goes into the details of the Asterisk configuration including setting up your connectivity, configuring extensions, setting up voicemail, and most of the common features most people would want right up front. Again, there isn’t enough space in a single book to cover all of features that are built into Asterisk.

The current state of Asterisk development including the few tools to aid in administration are still geared heavily towards technically savvy individuals with Linux administration experience. Because of that, the book, while doing a good job at explaining the different configuration settings is still not quite for people without any solid technical background. Although projects like Asterisk@Home are making the installation and setup much easier, in order to really take advantage of Asterisk’s features, you will need to really understand concepts like the Asterisk dial plan which the book does a very good job at walking you through not only the basic setups but includes a few common advanced setup features.

One of the big problems with a large open source project like Asterisk is typically a major lack of documentation. VoIP Telephony with Asterisk fills this documentation gap quite nicely. Even though the Asterisk community is striving to provide documentation through the handbook project and the Wiki pages, VoIP Telephony with Asterisk puts everything you need to know to get started all in one nicely organized place. Amazon.com carries the book itself for $42.99 and the book/CD combo for $76.41. While the price may seem high, the hours of time that you will save by following the examples and learning the techniques from the book will easily pay for itself.

VoIP Telephony with Asterisk Signate www.signate.com

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