With VoIP hacking gaining ground here is a book titled Hacking Exposed VoIP which offers you tools and tricks to thwart an attack on VoIP systems. The book has been co-authored by David Endler, chair, VoIP Security Alliance and Mark Collier, CTO, SecureLogix Co. It is being labeled as a one stop solution for preventing attacks on VoIP system. In this book it has been explained in a detail manner regarding how a VoIP system could be hacked and a number of practical countermeasures have been stated for its safety.

The book in a chronological order starts with a potential hack through the process giving details regarding the physical foot printing, scanning and enumeration of a system and then exposes various kinds of attacks ranging from denial of service to application interception. In the book attacks have also been compared against VoIP systems from specific vendors.

It's a nice book which will certainly increase your knowledge on the various attacks that can affect the VoIP system and how one could thwart them. A must read for all administrators.