1 3GPP2 IMS Charging Infrastructure Presented for 3GPP2 TSG-X by Nick Mazzarella of Lucent Technologies September 25, 2004

2 3GPP2 IMS Charging Infrastructure Contents  Scope  3GPP2 Organization  3GPP2 IP Networking Model  Current Rev 0 Charging Structure  Architecture  Charging Functions and Correlations  Basic Flows  Evolution to Rev A Charging  Adding On-Line Charging  New Charging Functions  Possible Additional Enhancements  Harmonization between 3GPP and 3GPP2  Abbreviations and References

3 3GPP2 IMS Charging Infrastructure Scope Provide architecture and flows for charging for IMS services.  Objectives  Define principles of charging in an IMS network  Provide a description of the charging architecture  Provide the descriptions of events and triggers for the next generation of charging data.  Provide charging message flows along with charging data triggers, message content and format along with the transport of these messages using the Diameter protocol.

4 3GPP2 IMS Charging Infrastructure  Charging functions exist in several areas within TSG-X  CSN Work Group – Circuit Domain Charging  PDS Work Group – Packet Data Subsystem Charging  MMD Work Group - IMS Charging  This Presentation will focus on Charging in IMS

5 3GPP2 IMS Charging Infrastructure 3GPP2 Organizational Context TSG-X TSG-STSG-C TSG-A SC OP CSN PSN PDS MMS MMD CHARGING PRESENCE GoGq MMD Work Activities BAN

6 3GPP2 IP Networking Model All IP Network Architecture Model (NAM) Offline Data Bases Location Services Radio Access AAA Access Gateway OSAAS PDF MRFP MRCF MGCF MGW CSCF Legacy MS Domain TIA- 41 IP Networ k PST N SIPAS OSACS IMS PDSPDS Charging

7 Current Rev 0 Charging Structure Home(B) = Visited(B) AS MRFC S-CSCF S- I- I- P- P- BGCF BS Rf Home(A) = Visited(A) AS AAA MRFC S-CSCF S- I- I- P- P- BGCF BS Rf AAA BGCF PDSN 1. Off-line IMS Charging architecture for non-roaming scenario Basic Architecture MGCF

8 Current Rev 0 Charging Structure AS MRFC S - CSCF S - I - CSCF I - CSCF P - P - BGCF BS Rf AS AAA MRFC S - CSCF S - I - I - P - P - BGCF BS Rf AAA Visited(A) BS P - CSCF P - AAA Rf PDSN Visited(B) AAA BS P - CSCF P - Rf PDSN 2. Off-line IMS Charging architecture for roaming scenario Basic Architecture MGCF Home(B) Home(A)

9 Current Rev 0 Charging Structure  Charging Functions-  AAA AAA provides the mechanism to transfer charging (i.e. Accounting) information from the IMS nodes to the network operator's chosen Billing System(s). *Does not define actual end user billing records. Main functions : The collection of Session charging information from the IMS node Intermediate data storage buffering The transfer of the charging data to the off-line billing systems

10 Current Rev 0 Charging Structure Charging Correlation Levels -  Correlation between the session and the media records  The IMS Charging ID may be used to correlate session level charging records with media records.  Correlation at media component level  For a session comprising several media components (such as audio and video), charging data is generated for each media component and needs to be correlated between network elements and between media component records.  Correlation within a session  The IMS Charging ID may be used to correlate the charging data between network elements.

11 Current Rev 0 Charging Structure  Charging Correlation Capabilities To support the correlation of charging information, the following capabilities apply to:  The correlation of charging information for an IMS session is based on the use of IMS Charging Identifiers (ICIDs).  The first IMS network entity within the SIP signalling path is responsible for assigning an ICID.  The ICID is passed to all IMS network entities in the SIP signalling path. This is performed using SIP signalling.

12 Current Rev 0 Charging Structure  The charging correlation identifiers (ICIDs, TCIDs) will not be passed to the UE.  Charging Correlation Capabilities-  For the charging correlation between the ICN and the IMS, one or more Transport Charging IDs, which identify the channels of the session, may be passed from the ICN to the IMS.  The Transport Charging IDs (TCIDs) are passed by the P- CSCF to the S-CSCF and the AS using SIP signalling. Along with the ICID, the S-CSCF includes the TCIDs in the off-line charging record.  The ICID applies for the duration of the event with which it is associated.

13 Current Rev 0 Charging Structure  Supported Off-line Interface Types  Rf Offline (Post Paid) Charging Reference Point between an IMS Network Entity or an AAA  Rf and ISC Interfaces  All other IMS nodes (S-CSCF, P-CSCF, I-CSCF, BGCF and MGCF) apply offline charging via the Rf interface using the AAA address as received via SIP signaling or the locally configured AAA address.

14 Current Rev 0 Charging Structure Basic Off-Line Charging Message Flows UE P-CSCF S- AAA (visited) Visited Network AAA (home) Home Network 1. INVITE Service Control More SIP signalling OK (Invite) 3. Accounting Request [Start] 4. Accounting Answer OK (Invite) 5. Accounting Request [Start] 6. Accounting Answer Open a P-CSCF AIR OK (Invite) 1. INVITE Service Control Open a S-CSCF AIR SIP Session established More SIP signalling 1. Message Sequence Chart for Session Establishment (Mobile Origination)

15 Current Rev 0 Charging Structure Basic Off-Line Charging Message Flows- UE P-CSCF S-CSCF AAA (visited) Visited Network AAA (home) Home Network I-CSCF 1. INVITE Cx Querywith the HSS 2. Accounting Request [Event] 3. Accounting Answer Open I-CSCF AIR Service Control 1. INVITE OK 5. Accounting Request [Start] 6. Accounting Answer Open P-CSCF AIR OK 7. Accounting Request [Start] 8. Accounting Answer Open S-CSCF AIR OK SIP Session established More SIP signalling 2. Message Sequence Chart for Session Establishment (Mobile Termination)

16 Current Rev 0 Charging Structure Basic Off-Line Charging Message Flows- 3. Message Sequence Chart for Session Release – Mobile Initiated UE P-CSCF S- AAA (visited) Visited Network AAA (home) Home Network 1. BYE Service Control OK 1. BYE 2. Accounting Request [Stop] 3. Accounting Answer Close the P-CSCF AIR 4. Accounting Request [Stop] 5. Accounting Answer Close the S-CSCF AIR

17 Evolution to Rev A Charging  Where applicable, 3GPP2 will adapt some IMS charging functionality from 3GPP  Revision A Charging will provide standardized functionality for On-line Charging.  On-line Charging Architecture has already been defined in 3GPP2 documentation  New on-line charging stage 3 flows will have to be developed  3GPP2 wishes to maintain harmonization with 3GPP Release 6 Charging functionality.

18 Evolution to Rev A Charging On-line IMS Charging architecture * In 3GPP Rel 5 and 6, a Media Gateway has been added with an Ro interface. 3GPP2 may consider this as a revision to Rev 0 Architecture.

19 Evolution to Rev A Charging The Event Charging Function (ECF) performs event-based charging (content charging). It makes use of the rating function in order to determine the value of the service rendered. The ECF may correlate several event-based charging requests.  Added Functions for On-line Charging  Session Charging Function (SCF) Responsible for Session Charging including the session control such as e.g. session termination.  Bearer Charging Function (BCF) The Bearer Charging Function performs the Bearer Charging  Event Charging Function (ECF)

20 Evolution to Rev A Charging The CPCF manages the account that is maintained for the content provider. Upon receipt of a charging request from the AS/MRFC, the CPCF processes the request and relays it to the SCCF.  Added Functions for On-line Charging  Subscriber Content Charging Function (SCCF) The SCCF is always located in the same operator network as the account of the subscriber, and handles content charging requests that are made when the subscriber accesses the content.  Content Provider Charging Function (CPCF)

21 Evolution to Rev A Charging e.g. Call Data Records (CDRs)  Additional Enhancements  3GPP2 TSG-X MMD will evaluate additional charging functions and decide which to include.

22 Evolution to Rev A Charging Current 3GPP Rel. 5 to 3GPP2 Rev. 0 Correlation 3GPP TS V GPP Ts V GPP2 X.P GPP2 X.P Possible Correlation for 3GPP Rel. 6 to 3GPP2 Rev. A * 3GPP TS V6.0 3GPP TS V6.0 3GPP TS V6.0 3GPP2 X.P A 3GPP2 X.P A 3GPP2 X.P A May be enhanced by…. *Currently under study in TSG-X MMD Group Harmonization between 3GPP and 3GPP2 Harmonization

23 Symbols and Abbreviations Abbreviations AAAAuthentication, Authorization, and Accounting ACAAccounting-Answer ACRAccounting-Request AIRAudit Information Record ASApplication Server AVPAttribute Value Pair BCFBilling Control Function BSBilling System CPCFContent Provider Charging Function CSCFCall Session Control Function (I-Interrogating; P-Proxy; and S-Serving) ECFEvent Charging Function IAM Initial Address Message ICNIP Connectivity Network IECImmediate Event Charging IMSIP Multimedia Subsystem ISCIMS Service Control MGCFMedia Gateway Control Function MRFCMedia Resource Function Controller MRFPMultimedia Resource Function Processor OCSOnline Charging System REL Release Message SCCFSubscriber Content Charging Function SDPSession Description Protocol SIPSession Initiation Protocol UEUser Equipment

24 References  3GPP2 X.S v1.0 IP Multimedia Subsystem - Accounting Information Flows and Protocol  3GPP2 X.S v1.0 IP Multimedia Subsystem - Charging Architecture