This book was written for the thousands of IT professionals-from CIOs to circuit-switched telecom engineers-who are now responsible for deploying and maintaining secure VoIP networks. The book explains the impact on your VoIP network of PSTN, SIP, H.323, firewalls, NAT, encryption, and the regulatory environment. Coverage includes evaluation, design, integration, and management of VoIP networking components, including IP telephones, gateways, gatekeepers, registration servers, media servers, and proxy servers. Throughout the book, the authors rely on their extensive real-world experience to provide readers with practical applications and solutions.