Asterisk manual

Asterisk : The Future of Telephony
™

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SECOND EDITION

Asterisk : The Future of Telephony
™

Jim Van Meggelen, Leif Madsen, and Jared Smith

Beijing • Cambridge • Farnham • Köln • Paris • Sebastopol • Taipei • Tokyo

Asterisk™: The Future of Telephony, Second Edition
by Jim Van Meggelen, Leif Madsen, and Jared Smith
Copyright © 2007, 2005 O’Reilly Media, Inc. All rights reserved.Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472 O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://safari.oreilly.com). For more information, contact our corporate/ institutional sales department: (800) 998-9938 orcorporate@oreilly.com.

Editor: Mike Loukides Copy Editor: Sanders Kleinfeld Production Editor: Laurel R.T. Ruma Proofreader: Tolman Creek Design Printing History:
June 2005: August 2007: First Edition. Second Edition.

Indexer: Joe Wizda Cover Designer: Karen Montgomery Interior Designer: David Futato Illustrators: Robert Romano and Jessamyn Read

Nutshell Handbook, the Nutshell Handbook logo, and theO’Reilly logo are registered trademarks of O’Reilly Media, Inc. Asterisk™: The Future of Telephony, the image of starfish, and related trade dress are trademarks of O’Reilly Media, Inc. Asterisk™ is a trademark of Digium, Inc. Asterisk: The Future of Telephony is published under the Creative Commons “Commons Deed” license (http://creativecommons.org/licenses/by-nc-nd/2.5/ca/). While everyprecaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.

TM

This book uses RepKover™, a durable and flexible lay-flat binding. ISBN-10: 0-596-51048-9 ISBN-13: 978-0-596-51048-0 [M]

This book is dedicated to Rich Adamson (1947–2006). Thanks forshowing us the meaning of community.

Table of Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv 1.
VoIP: Bridging the Gap Between Traditional and Network Telephony Massive Change RequiresFlexible Technology Asterisk: The Hacker’s PBX Asterisk: The Professional’s PBX The Asterisk Community The Business Case This Book

A Telephony Revolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 3 5 5 6 8 9

2.

Preparing a System for Asterisk . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Server Hardware Selection Environment Telephony...