Customer Reviews

IP Telephony: Deploying Voice-over-IP Protocols

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Warning! This is a very technical book, that is directed at the communications engineer who wants a detailed explanation of VoIP. It describes the numerous VoIP standards, but in a much more meaningful way than the official standards documents.

H.323, SIP and MGCP are each given a chapter. These are the most prominent of the VoIP standards, and deserve your attention. The chapters explain the standards to enough depth to convey the main functionalities. Plus, you are now equipped with enough knowledge to actually read the standards documents if you so desire.

If you are wondering about H.248 and SS7, then be aware that the authors have deliberately refrained from covering these here. For various reasons - SS7 being seen as too far afield from VoIP.

This is a well-written text; it compiles a lot of good information on important issues. I enjoy reading it, because there is a lot of info on things I don't understand. For example, it has an introductory description of how faxing works, then touches on how T.38 works with that approach.

There's also some information on what you'll usually see in equipment, and about movements afoot that aren't quite widespread as yet -- e.g., ENUM lookups for routing calls.

The author sprinkles in his opinions and technical/aesthetic tastes, however. While it's very informative, some sections read like opinion from a magazine like MacWorld. For example, the authors praise H.323 for its greatness, but criticize SIP for being as a bunch of vendor hacks.

But it's missing some key features -- like a useful index (it has one of those sparse six-page indexes for a 380-page book), or even a bibliography! The lack of a bibliography is particularly offensive. For example, the authors claim that "95% of VoIP minutes worldwide" are controlled with H.323, but provides no basis for that claim.

This book itself is pretty good. It is comprehensive in its distillation of the RFC's so I don't have to read them. My one complaint about the content of this book is my perception of their bias against SIP, although they still do a good job of fleshing it out. However, it is a little annoying that it seems like every other page, just when it starts to get good, they will refer you to the companion book. So my advice is, yeah, go ahead and purchase this book, but you might as well go ahead and buy the other one too.