I've always been interested about VoIP security...it seems many networks running VoIP are now considering their security options (years after initial deployment). When I first looked through this book, I was unimpressed. It seems like the book spends A LOT of time talking through foundations of H.323, MGCP, SIP, encryption, authentication, etc... (just general security topics and voice concepts). However, Chapter 6 (Pages 128-173) essentially makes the book worth the purchase. It walks through in "attack-counterattack" form ways that people can destroy your voice network and ways to mitigate these attacks. I really enjoyed the fact that the author shows you how to pull off the attack yourself in many of the sections so you can test to see if you've properly secured the network.

So...for the most part, the book could have been 50 pages long and I would have been happy with it. I guess that's about as much as I read from most books anyhow.