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Presence in the IP Multimedia Subsystem. Happenhofer Marco June 26, 2008. Switched of your mobile phone?. Will only prevent ringing of your phone, but it will not prevent the caller to call you and the caller will not know why he did not reach you. Imaging:
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Presencein the IP Multimedia Subsystem Happenhofer Marco June 26, 2008
Switched of your mobile phone? • Will only prevent ringing of your phone, but • it will not prevent the caller to call you and • the caller will not know why he did not reach you
Imaging: • “You could inform your friends and buddies, if you are going to accept call now.” • Would it be useful? • Would you use this service? • And, would you pay for it ?
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
Definition of Presence “A presence [..] system allows users to subscribe to each other and be notified of changes in state, [..].”[IETF] “A Presence Service is a software system whose role is to collect and disseminate presence information, subject to a wide variety of controls.“ OMA „In computer and telecommunications networks, presence information is a status indicator that conveys ability and willingness of a potential communication partner - for example a user to communicate.“ Wikipedia[en] “Presence describes the social willingness and technical possibilities (of a subscriber) to accept a connection.”
History • Presence was no topic in plain old telephone systems, because no display possibilities and analogue processing • With Internet chats Presence become popular, because computer could display this state and manage buddy lists (e.g. ICQ) • Skype as first telephone system uses also Presence to display the current state of the buddies • IETF specified also mechanisms to convey presence information
Standardisation bodies • IETF (Internet Engineering Task Force)specifies IP, SIP, PIDF, XCAP, etc. mostly technologies used by presence. www.ietf.org • 3GPP (3th Generation Partnership Project) specifies the practical implementation of IMS. www.3gpp.org • OMA (Open Mobile Alliance) concentrates on services and enablers. www.oma.org
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
What information carries Presence Presence describes the state of a buddy binary with „online“ or „offline“. in a homogen communication system
What information could be carried by Presence • Presence state with open/closed and comments like (busy, call proceeding, etc.) • Communication media (text, audio or video) • Communication capabilities (like video telephone, resolution, etc.) • Supported Codecs • Communication protocols (sip, smtp, etc. ) • Addresses (IP, URIs, etc. ) • Location (e.g. @office) / Local Time • Mood / present activities (e.g. in lecture) / Timetable • Privacy aspects
Architecture & Roles Online Busy
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
SIP and the Event Notification Framework B. Roach, „ Session Initiation Protocol (SIP)-Specific Event Notification“, IETF, RFC 3265 J. Rosenberg, „ A Presence Event Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3856
Presence encoding - PIDF <?xml version="1.0" encoding="UTF-8"?> <presence entity="pres:alice@opertaor.net"> <tuple id="bs35r9"> <status> <basic>open</basic> </status> <contact priority="0.8">sip:alice@opertaor.net</contact> <note xml:lang="en">Don't Disturb Please!</note> <timestamp>2001-10-27T16:49:29Z</timestamp> </tuple> </presence> H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W. Carr, J. Peterson, „ Presence Information Data Format (PIDF)“, IETF RFC 3863
Solution of these problems • A. Niemi, Ed., „ Session Initiation Protocol (SIP) Extension for Event State Publication“, IETF, RFC 3909 • A. B. Roach, B. Campbell, J. Rosenberg, „ A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists“, IETF, RFC 4662
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
IMS 3GPP TS 23.002
IMS Access point for other IMS systems Stores account data (HLR) Executes service relevant tasks Access point for own subscriber executes policies and security tasks User Equipmenty
Components in IMS Presence Source:Entity which creates presence information (presentity) Presence Server:Entity which stores the presence state of several entities Presence XDMS:Entity which stores which watcher is allowed to see which data Watcher:Entity which wants to follow the presence state Resource List Server:Entity which collects presence information for the watcher RLS XDMS:Entity which stores buddylists for watcher Clients, for creating and presenting presence information Server which process presence information Servers which store policies
The Architecture in IMS Accepted Policy for Alice from Carol? Accepted Get Carol state Get Bob state My buddies? List of Alice buddies? Alice buddies: BobCarol Policy for Alice from Bob?
Useability • Updating the presence state (by the user)“I am online, but I am still in a meeting!” • Configuring police rules for all watcher ”What are the watchers allowed to see?”
Privacy and Law • presence is a person related information and should be protected against unauthorized access • presence server executes policies, which are configured by the presentity • watcher could forward the presence information • network operator known about the presentity • Datenschutzgesetz 2000
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
LTE Requires: Return of invest LTE Offers: High bandwidthlow latency Requires: Packet switched signalling Requires: High bandwidthlow latency Offers: fees Offers: Packet switched signalling customer IMS Requires: Return of invest Offers: fees “Requires”: Services Offers: End2end signalling, QoS, charging, service interfaces Cashcow Killerapplication packet based services Requires: End2end signalling, charging, service interfaces Offers: Services Offers: Services legacy services Requires: End2end signalling, charging, QoS
Presence as Cashcow • could get very hard to sell basic presence • have to pay for all buddies over about 20 buddies (social aspects, removing old friends) • Does presence reduce the number of voice minutes (fewer voice box calls) ? • Extend presence functionality for paying customers (DSG2000)
Presence as Killerapplication for LTE/IMS • Killerapplication = driver for a new technology (WWW was the killerapplication for the internet) • UMTS had no killerapplication (most thought video telephony is it, but pure internet was it) • Needs a critical number of user in this service, before there is no possibility to sell • Offer as bundle with 4G/telephone account • Maybe presence gateways for 3G to 4G presence
Agenda • Meaning of Presence • Architecture • Presence in SIP • Presence in IMS • Business Model and relevance to LTE • Conclusions
Conclusions • presences indicates if somebody if wiling to accept a connection • P2P Presence works, but Server based scales • Easy configuration, intuitive meaning and easy usage of presence • privacy & DSG2000 • not realistic to sell as a stand alone service (extend it) • could motivate people to switch from 3G/ISDN to 4G/IMS
References • J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler, „SIP: Session Initiation Protocol“, IETF, RFC 3261 • M. Day, J. Rosenberg, H. Sugano, „ A Model for Presence and Instant Messaging”, IETF, RFC 2778 • A. B. Roach, „ Session Initiation Protocol (SIP)-Specific Event Notification“, IETF, RFC 3265 • J. Rosenberg, „ A Presence Event Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3856 • J. Rosenberg, „ A Watcher Information Event Template-Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3857 • H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W. Carr, J. Peterson, „ Presence Information Data Format (PIDF)“, IETF RFC 3863 • A. Niemi, Ed., „ Session Initiation Protocol (SIP) Extension for Event State Publication“, IETF, RFC 3909 • E. Burger, Ed., „ A Mechanism for Content Indirection in Session Initiation Protocol (SIP) Messages“, IETF, RFC 4483 • H. Khartabil, E. Leppanen, M. Lonnfors, J. Costa-Requena, „ Functional Description of Event Notification Filtering”, IETF, RFC 4660 • A. B. Roach, B. Campbell, J. Rosenberg, „ A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists“, IETF, RFC 4662 • J. Rosenberg, „ The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)“, IETF, RFC 4825 • 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects;Presence Service;Architecture and functional description(Release 8), TS 23.141 V8.1.0 (2008-06) • 3rd Generation Partnership Project;Technical Specification Group Core Network and Terminals;Presence service using the IP Multimedia (IM) Core Network (CN) subsystem;Stage 3 (Release 8), TS 24.141 V8.1.0 (2008-06) • Presence SIMPLE Architecture (Candidate Version 1.1 – 28 Jan 2008), Open Mobile Alliance (OMA-AD-Presence_SIMPLE-V1_1-20080128-C) • Enabler Release Definition for OMA Presence SIMPLE (Candidate Version 1.1 – 28 Jan 2008), Open Mobile Alliance (OMA-ERELD-Presence_SIMPLE-V1_1-20080128-C) • XML Document Management Architecture (Candidate Version 2.0 – 24 Jul 2007), Open Mobile Alliance (OMA-AD-XDM-V2_0-20070724-C) • Enabler Release Definition for XML Document Management (Candidate Version 2.0 – 24 Jul 2007), Open Mobile Alliance(OMA-ERELD-XDM-V2_0-20070724-C)
Thank you for your attention. Busy ready f. questions