"This book is like a good tour guide.It doesn't just describe the major attractions; you share in the history, spirit, language, and culture of the place." --Henning Schulzrinne, Professor, Columbia University Since its birth in 1996, Session Initiation Protocol (SIP) has grown up. As a richer, much more robust technology, SIP today is fully capable of supporting the communication systems that power our twenty-first century work and life. This second edition handbook has been revamped to cover the newest standards, services, and products. You'll find the latest on SIP usage beyond VoIP, including Presence, instant messaging (IM), mobility, and emergency services, as well as peer-to-peer SIP applications, quality-of-service, and security issues--everything you need to build and deploy today's SIP services. This book will help you Work with SIP in Presence and event-based communications Handle SIP-based application-level mobility issues Develop applications to facilitate communications access for users with disabilities Set up Internet-based emergency services Explore how peer-to-peer SIP systems may change VoIP Understand the critical importance of Internet transparency Identify relevant standards and specifications Handle potential quality-of-service and security problems