The 3G IP Multimedia Subsystem (IMS) The 3G IP Multimedia Subsystem (IMS): Merging the Internet and the Cellular Worlds, Second Edition Gonzalo Camarillo and M iguel A . G ar cıa-´ M ar tın´ © 2006 John Wiley & Sons Ltd. ISBN: 0-470-01818-6 The 3G IP Multimedia Subsystem (IMS) Merging the Internet and the Cellular Worlds Second Edition Gonzalo Camarillo Ericsson, Finland Miguel A. Garc´ıa-Mart´ın Nokia Research Center, Finland John Wiley & Sons, Ltd Copyright c 2006 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com All Rights Reserved. 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Library of Congress Cataloging-in-Publication Data Camarillo, Gonzalo. The 3G IP multimedia subsystem (IMS) : merging the Internet and the cellular worlds / Gonzalo Camarillo, Miguel A. Garc´ıa-Mart´ın.–2nd ed. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-470-01818-7 (cloth : alk. paper) ISBN-10: 0-470-01818-6 (cloth : alk. paper) 1. Wireless communication systems. 2. Mobile communication systems. 3. Multimedia communications. I. Garc´ıa-Mart´ın, Miguel A. II. Title. TK5103.2.C35 2006 621.384–dc22 2005026863 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN-13 978-0-470-01818-7 (HB) ISBN-10 0-470-01818-6 (HB) Typeset by Sunrise Setting Ltd, Torquay, Devon, UK. Printed and bound in Great Britain by Antony Rowe Ltd, Chipenham, Wiltshire. This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production. To my parents, Anselmo and Isabel; my brothers, Alvaro, Daniel, and Ignacio; and Viviana. They all are a source of energy and motivation in everything I do. Gonzalo To my daughter Maria Elizabeth, who was born at the time I started writing this book, she is the sunshine of my life; my wife Jelena, who provided me with all the support and love I needed; my parents, Jos´e and Mari-Luz, my aunt Feli, my brother Javier Jos´e who, through the distance, encouraged and supported me during this project. Miguel Angel Contents Foreword by Stephen Hayes xvii Foreword by Allison Mankin and Jon Peterson xix About the Authors xxi Preface to the Second Edition xxiii Preface to the First Edition xxv Acknowledgements xxvii Part I Introduction to the IMS 1 1 IMS Vision: Where Do We Want to Go? 5 1.1 TheInternet.................................. 5 1.2 TheCellularWorld............................... 6 1.3 WhydoweneedtheIMS?........................... 6 1.4 RelationbetweenIMSandnon-IMSServices................. 8 2 The History of the IMS Standardization 9 2.1 RelationsbetweenIMS-relatedStandardizationBodies............ 9 2.2 InternetEngineeringTaskForce........................ 10 2.2.1 StructureoftheIETF......................... 10 2.2.2 WorkingGroupOperations...................... 11 2.2.3 TypesofRFCs............................ 12 2.3 ThirdGenerationPartnershipProject..................... 13 2.3.1 3GPPStructure............................ 14 2.3.2 3GPPDeliverables.......................... 15 2.4 ThirdGenerationPartnershipProject2 .................... 16 2.4.1 3GPP2Structure........................... 16 2.4.2 3GPP2Deliverables......................... 16 2.5 IETF-3GPP/3GPP2Collaboration....................... 17 2.5.1 InternetArea............................. 18 2.5.2 OperationsandManagementArea.................. 18 2.5.3 TransportArea............................ 19 viii CONTENTS 2.6 Open Mobile Alliance . .......................... 19 2.6.1 OMAReleasesandSpecifications.................. 20 2.6.2 RelationshipbetweenOMAand3GPP/3GPP2........... 21 2.6.3 RelationshipbetweenOMAandtheIETF.............. 22 3 General Principles of the IMS Architecture 23 3.1 FromCircuit-switchedtoPacket-switched................... 23 3.1.1 GSMCircuit-switched........................ 23 3.1.2 GSMPacket-switched........................ 24 3.2 IMSRequirements............................... 24 3.2.1 IP Multimedia Sessions . ...................... 25 3.2.2 QoS.................................. 25 3.2.3 Interworking............................. 26 3.2.4 Roaming............................... 26 3.2.5 ServiceControl............................ 26 3.2.6 RapidServiceCreation........................ 27 3.2.7 Multiple Access . .......................... 27 3.3 OverviewofProtocolsusedintheIMS.................... 27 3.3.1 SessionControlProtocol....................... 27 3.3.2 TheAAAProtocol.......................... 28 3.3.3 OtherProtocols............................ 29 3.4 OverviewofIMSArchitecture......................... 29 3.4.1 TheDatabases:theHSSandtheSLF................ 30 3.4.2 TheCSCF............................... 31 3.4.3 TheAS................................ 33 3.4.4 TheMRF............................... 35 3.4.5 TheBGCF.............................. 35 3.4.6 TheIMS-ALGandtheTrGW.................... 35 3.4.7 ThePSTN/CSGateway........................ 36 3.4.8 HomeandVisitedNetworks..................... 38 3.5 IdentificationintheIMS............................ 39 3.5.1 Public User Identities . ...................... 40 3.5.2 Private User Identities . ...................... 40 3.5.3 The Relation between Public and Private User Identities . 41 3.5.4 Public Service Identities . ...................... 42 3.6 SIM,USIM,andISIMin3GPP........................ 42 3.6.1 SIM.................................. 43 3.6.2 USIM................................. 43 3.6.3 ISIM................................. 45 Part II The Signaling Plane in the IMS 47 4 Session Control on the Internet 51 4.1 SIP Functionality . .......................... 51 4.1.1 SessionDescriptionsandSDP.................... 51 4.1.2 TheOffer/AnswerModel....................... 52 4.1.3 SIPandSIPSURIs.......................... 53 4.1.4 UserLocation............................. 54 CONTENTS ix 4.2 SIP Entities . .................................. 55 4.2.1 ForkingProxies............................ 57 4.2.2 RedirectServers........................... 58 4.3 MessageFormat................................ 59 4.4 The Start Line in SIP Responses: the Status Line ............... 59 4.5 TheStartLineinSIPRequests:theRequestLine............... 60 4.6 HeaderFields.................................. 60 4.7 MessageBody................................. 62 4.8 SIPTransactions................................ 63 4.9 MessageFlowforSessionEstablishment................... 64 4.10SIPDialogs................................... 67 4.10.1 Record-Route, Route,andContact HeaderFields........ 70 4.11ExtendingSIP................................. 70 4.11.1 New Methods . ........................... 72 4.12 Caller Preferences and User Agent Capabilities . ............... 72 4.13 Reliability of Provisional Responses . ................... 73 4.14Preconditions.................................. 76 4.15EventNotification............................... 77 4.15.1HighNotificationRates........................ 79 4.16SignalingCompression............................. 80 4.16.1SigCompExtendedOperations.................... 81 4.16.2StaticSIP/SDPDictionary...................... 82 4.17ContentIndirection............................... 82 4.18TheREFERMethod.............................. 85 5 Session Control in the IMS 87 5.1 PrerequisitesforOperationintheIMS..................... 88 5.2 IPv4andIPv6intheIMS........................... 89 5.3 IP Connectivity Access Network . ....................... 90 5.4 P-CSCFDiscovery..............................