Safari or accessing the online edition, Safari please e-mail customer-service@safaribooksonline.com Books Online Addison Adobe Press Cisco Press Press Microsoft Press Press ALPHA FINANCIAL TIMES Wesley lynda.com Riders O'REILLY® Peachpit Press WILEY PRENTICE Publishing microsystems Redbooks Alan B. Johnston understanding the Session Initiation Protocol second edition Understanding the Session Initiation Protocol Second Edition For a listing of recent titles in the Artech House Telecommunications Library, turn to the back of this book. Understanding the Session Initiation Protocol Second Edition Alan B. Johnston Artech House Boston London www.artechhouse.com Library of Congress Cataloging-in-Publication Data A catalog record of this title is available from the Library of Congress British Library Cataloguing in Publication Data Johnston, Alan B. SIP: Understanding the Session Initiation Protocol. -2nd ed. - (Artech House telecommunications library) 1. Computer network protocols I. Title 004.6'2 ISBN 1-58053-655-7 Cover design by Lisa Johnston © 2004 ARTECH HOUSE, INC. 685 Canton Street Norwood, MA 02062 All rights reserved. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. All terms mentioned in this book that are known to be trademarks or service marks have appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. International Standard Book Number: 1-58053-655-7 10987654321 To Lisa Contents Foreword to the First Edition Preface to the Second Edition Preface to the First Edition SIP and the Internet Signaling Protocols The Internet Engineering Task Force A Brief History of SIP Internet Multimedia Protocol Stack 1.4.1 Physical Layer 1.