xxvi Foreword Cisco IP Telephony (CIPT), Second Edition is an excellent self-study resource for the CCVP CIPT exam. Whether you are studying to become CCVP certified or are simply seeking to gain a better understanding of VoIP and PSTN components and technologies, you will benefit from the information presented in this book. Cisco Press Self-Study Guide titles are designed to help educate, develop, and grow the community of Cisco networking professionals. As an early-stage exam preparation product, this book presents a detailed and comprehensive introduction to the technologies used to install, configure, and support Cisco CallManager 4.1 in a Cisco network, including such features as security and video. Developed in conjunction with the Cisco certifications team, Cisco Press books are the only self-study books authorized by Cisco Systems. Most networking professionals use a variety of learning methods to gain necessary skills. Cisco Press self-study titles are a prime source of content for some individuals and can also serve as an excellent supplement to other forms of learning. Training classes, whether delivered in a classroom or on the Internet, are a great way to quickly acquire new understanding. Hands-on practice is essential for anyone seeking to build, or hone, new skills. Authorized Cisco training classes, labs, and simulations are available exclusively from Cisco Learning Solutions Partners worldwide. Please visit http://www.cisco.com/go/training to learn more about Cisco Learning Solutions Partners. I hope and expect that you'll find this guide to be an essential part of your exam preparation and a valuable addition to your personal library. Don Field Director, Certifications Cisco Systems, Inc. August 2006