Integrating Charging and Rating into the IMS Platform Joe Hogan CTO and Founder Openet Telecom

Agenda Introduction Developing and launching services and applications quickly and cost effectively How can existing OSS systems evolve to IMS architecture Examining the impact of IMS services on OSS/BSS systems Real-Time Charging models as a natural towards IMS Transferring charging information from the IMS nodes to the billing system Utilizing real-time rating for IMS applications

Rapid service creation and deployment IMS architecture facilitates faster service creation and delivery. Horizontal service architecture for service delivery: Avoids stovepipe challenges previously associated with deploying services Improved scalability of service offerings (independent of session control and transport) Increased control over service lifecycle Service transparency

Evolving to IMS Architecture 3G Charging Architecture From 3GPP (TS 32.240) Billing Domain ONLINE CHARGING OFFLINE WLAN BGCF MGCF MRFC SIP AS CRF AF CDF CS - NE SGSN CGF OCS IMS GWF P CSCF I S Service GGSN TPF

IMS Charging Interface Architecture

Existing OSS systems evolution Critical that investment in OSS systems is leveraged. Departure from legacy prepaid platforms and reliance on vendor defined architectures. Progression of rating and intelligence capabilities to the network edge. Online transaction processing treatment for all subscribers irrespective of payment method. ‘Flexible Transactionality’ is at the heart of IMS service lifecycle control for service creation, aggregation, orchestration, discovery, retirement and delivery.

Impact of IMS services on OSS/BSS systems IMS will deliver innovative services that shall demand the OSS/BSS system handle complex pricing strategies Batch based systems fall short of the real-time, low latency processing requirements. Network edge rating required. Support required for standards based input interfaces (e.g. Rf, Ro). Diameter rich protocol, non trivial to implement Interoperability testing critical to success Session performance and reliability criteria must be met. Irrespective of pre and post payment for services. Much greater volumes of usage data from network nodes. Increased correlation challenges.

IMS Online and Offline Charging Online Charging Used for pre-paid account management. Subscribers account balance is checked and authorisation is received in real-time before a service is provided. Three types of credit control operation for online charging: Immediate Event Charging (IEC) - Event Charging with Unit Reservation (ECUR) Session Charging with Unit Reservation (SCUR). Offline Charging Used for post-paid account management. Subscriber is billed after the service is delivered. Customer data records are aggregated and sent to the Billing System in real-time or batch. The following types of accounting data can be sent: START session accounting INTERIM session accounting STOP session accounting EVENT accounting data.

IMS Event Based Charging Manages charging for single events: Direct Debit Service price enquiry Balance enquiry Refunds Offline event-based charging is performed by the CCF A single CDR is generated for the event which can be correlated and sent to the Billing System. Online event-based charging is performed by the OCS Authorisation, credit control and account balance management are performed for one or more events. Communicates with the rating function to determine the value of the requested event. Communicates with Credit Control to perform credit reservation and account balance management.

Session Based Charging Manages the charging of a subscriber session such as multimedia gaming, video-conferencing etc. Offline session-based charging is performed by the CCF. CDR(s) are generated for the session and are aggregated and correlated before being sent to the Billing System. Online session-based charging is performed by the OCS Authorisation, credit control and account balance management are performed for the session. Communicates with the rating function to determine the value of a requested service. Communicates with Credit Control to perform credit reservation and account balance management. Graceful service termination supported as subscribers account goes to zero.

Interfaces for Offline Charging IMS Interface Description Bi Charging data collection interface between a CCF and a Billing System. Rf All data communication for offline charging between IMS nodes and the CCF. Bp Charging data collection interface between a CGF and a Billing System. Ga Charging data collection interface between a CDR transmitting unit (GGSN/SGSN) and a CDR receiving unit such as a CGF.

Interfaces for Online Charging IMS Interface Description Rb Online Charging Reference Point between Session Charging Function and Correlation Function. Rc Online Charging Reference Point between Event Charging Function and the Correlation Function. Re Online Charging Reference Point towards a Rating Function. Ro Online Charging Reference Point between an Application Server or MRFC and the Event Charging Function.

Real-Time Charging Models as a natural migration towards IMS Valuable experience gained with existing charging models in wireless space e.g. packet switched domain. Gn Gi BTS MSC SGSN WAP GW Cisco CSG Cisco SESM Portal Volubill D2CP GGSN Intelligent GGSN Gaming Server Music Server Self-Help Server UMS Server Etc. MMSC ProQuent MSSP EDR / RTCU Cisco SSG Gn Probe Netspira Internet IMS MFR, MGCF CSCF, etc. CDR Charging Customer and Product Info DWH Fraud Postpaid Billing Balance Mgmt System(s) - Billing System - IN Platform - CRM - Etc External Rating - Rating Engine - IN Platform - Billing System - Etc Rating G-CDR EDR RTCU S-CDR - Real-Time Content Usage Events Key - Policy Controller - Policy Enforcers xDR - Post Service Delivery Usage Events

Transferring charging information from the IMS nodes to the billing system Charging interfaces from the IMS core Session aggregation Correlation Account balance management Distribution

Charging interfaces from the IMS core 3GPP defined Rf interface for offline charging Based on Diameter Base Protocol Accounting from IETF AAA WG (RFC3588) ACR/ACA Messages 3GPP AVPs 3GPP defined Ro interface for online charging Based on Diameter Credit Control Application from IETF AAA WG (RFC4006) CCR/CCA Messages

Session aggregation Session based aggregation required for offline charging to produce P/I/S-CSCF, AS, MRFC, BGCF and MGCF CDRs Generated from Diameter ACRs (Start, Interim, Stop) Error handling conditions required

Correlation Correlation of IMS usage events is typically required before sending to BS. Correlation is possible on multiple levels: Intra level – using ICID key Inter level – e.g. with the PS domain Inter network – using the Inter Operator Identification (IOI) key

Account balance management For online charging interaction with the subscribers balance is required e.g. Query balance Increment balance Decrement balance Set balance to value Reserve units Commit reservation Release reservation

Distribution Bi interface loosely defined Many different BS vendors most using proprietary formats for input Typically file based (push/pull)

Utilizing real-time rating for IMS applications 3GPP have defined rating function within the OCS 3GPP online charging demands low latency which mandates network edge rating 3GPP services shall more sophisticated and consequently shall require a corresponding level of rating complexity and flexibility Rating engines shall need to be able to adapt rapidly to the constant shifting of offered services without dependence on the vendor