After struggling for years, you finally think you've got your network secured from malicious hackers and obnoxious spammers. Just when you think it's safe to go back into the water, VoIP finally catches on. Now your newly converged network is vulnerable to DoS attacks, hacked gateways leading to unauthorized free calls, call eavesdropping, malicious call redirection, and spam over Internet Telephony (SPIT). This book covers a wide variety of the publicly available exploit tools and how they can be used specifically against VoIP (Voice over IP) Telephony systems. The book covers the attack methodologies that are used against the SIP and H.323 protocols as well as VoIP network infrastructure. Significant emphasis will be placed on both attack and defense techniques. This book is designed to be very hands on and scenario intensive.