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This page intentionally left blank h IMS This page intentionally left blank THE IMS IP Multimedia Concepts and Services in the Mobile Domain Miikka Poikselka, Georg Mayer, Hisham Khartabil and Aki Niemi John wiley & Sons, Ltd Copyright © 2004 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.wileyeurope.com or www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. 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British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 0-470-87113-X Project management by Originator, Gt Yarmouth, Norfolk (typeset in 10/13pt Times) Printed and bound in Great Britain by TJ International, Padstow, Cornwall 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. Contents Foreword xvii Preface xix Acknowledgements xxi List of Figures xxiii List of Tables xxvii PART I: ARCHITECTURE 1 1 Introduction 3 1.1 Why the Internet Protocol Multimedia Subsystem was developed 3 1.2 Where did it come from? 5 1.2.1 From GSM to 3GPP Release 6 5 1.2.2 3GPP Release 99 (3GPP R99) 5 1.2.3 3GPP Release 4 6 1.2.4 3GPP Release 5 and Release 6 6 1.3 Other relevant standardization bodies 8 1.3.1 Internet Engineering Task Force 8 1.3.2 Open Mobile Alliance 9 1.3.3 Third Generation Partnership Project 2 9 2 IP Multimedia Subsystem Architecture 11 2.1 Architectural requirements 11 2.1.1 IP connectivity 11 2.1.2 Access independence 12 2.1.3 Ensuring quality of service for IP multimedia services 13 vi Contents 2.1.4 IP policy control for ensuring correct usage of media resources 13 2.1.5 Secure communication 14 2.1.6 Charging arrangements 14 2.1.7 Support of roaming 15 2.1.8 Interworking with other networks 16 2.1.9 Service control model 16 2.1.10 Service development 17 2.1.11 Layered design 17 2.2 Description of IMS-related entities and functionalities 18 2.2.1 Proxy-CSCF 19 2.2.2 Policy Decision Function 20 2.2.3 Interrogating-CSCF 21 2.2.4 Serving-CSCF 22 2.2.5 Home Subscriber Server 23 2.2.6 Subscription Locator Function 24 2.2.7 Multimedia Resource Function Controller 24 2.2.8 Multimedia Resource Function Processor 24 2.2.9 Application server 25 2.2.10 Breakout Gateway Control Function 26 2.2.11 Media Gateway Control Function 27 2.2.12 IP Multimedia Subsystem-Media Gateway Function 27 2.2.13 Signalling gateway 27 2.2.14 Security gateway 27 2.2.15 Charging entities 28 2.2.16 GPRS Service entities 28 2.3 IMS reference points 29 2.3.1 Gm reference point 30 2.3.2 Mw reference point 31 2.3.3 IMS Service Control reference point 32 2.3.4 Cx reference point 32 2.3.5 Dx reference point 38 2.3.6 Sh reference point 39 2.3.7 Si reference point 42 2.3.8 Dh reference point 42 2.3.9 Mm reference point 43 2.3.10 Mg reference point 43 2.3.11 Mi reference point 43 2.3.12 Mj reference point 43 2.3.13 Mk reference point 44 2.3.14 Ut reference point 44 2.3.15 Mr reference point 44 Contents vii 2.3.16 Mp reference point 44 2.3.17 Go reference point 45 2.3.18 Gq reference point 45 3 IMS Concepts 49 3.1 Overview 49 3.2 Registration 49 3.3 Session initiation 51 3.4 Identification 53 3.4.1 Identification of users 53 3.4.2 Identification of services (public service identities) 58 3.4.3 Identification of network entities 58 3.5 Identity modules 59 3.5.1 IP Multimedia Services Identity Module 59 3.5.2 Universal Subscriber Identity Module 60 3.6 Security services in the IMS 60 3.6.1 IMS Security Model 61 3.6.2 Authentication and Key Agreement 62 3.6.3 Network domain security 62 3.6.4 IMS access security for SIP-based services 66 3.6.5 IMS access security for HTTP-based services 70 3.7 Discovering the IMS entry point 72 3.8 S-CSCF assignment 73 3.8.1 S-CSCF assignment during registration 73 3.8.2 S-CSCF assignment for an unregistered user 75 3.8.3 S-CSCF assignment in error cases 75 3.8.4 S-CSCF de-assignment 75 3.8.5 Maintaining S-CSCF assignment 75 3.9 Mechanism for controlling bearer traffic 75 3.9.1 SBLP functions 77 3.10 Charging 91 3.10.1 Charging architecture 91 3.10.2 Charging information correlation 99 3.10.3 Charging information distribution 101 3.11 User profile 101 3.11.1 Service profile 101 3.12 Service provision 105 3.12.1 Introduction 105 3.12.2 Creation of the filter criteria 105 3.12.3 Selection of AS 107 3.12.4 AS behaviour 108