Charging in 2G to 5G SA mobile networks

The 2G/2G circuit switched domain called R4 supports prepaid and postpaid charging. Prepaid voice and SMS charging are implemented via the CAMEL architecture and postpaid charging is supported by a mediation and sending CDRs (Charging Data Record). The first section of the training describes mobile voice/SMS charging in the 2G/3G circuit switched domain.
The 2G/3G/4G/5G NSA packet switched domain offers online charging via the OCS (Online charging System). The OCS is flexible enough to support multiple charging models. For example, a mobile user may be billed based on connection time or the amount of data transferred. The user may also benefit from free access to certain websites. Some users may be served as prepaid users and others may be handled as postpaid users. The OCS can support all these use cases for a mobile network service provider. The 2nd section of the training describes the online charging architecture in the context of 2G to 5G NSA mobile data networks.
The 2G/3G packet switched domain implements the transfer of CDR from GPRS network nodes to a CGF (Charging Gateway Function) via the GTP’ protocol described in the 3rd section.
The 4G/5G NSA packet switched domain implements the transfer of CDR from the EPC network nodes to an OFCS (Offline Charging System) via the offline charging Rf interface which may be implemented via GTP’ or via DIAMETER as described in the 4th section.
The IMS domain for VoLTE/VoWiFi/EPS FallBack/VoNR services implements online and offline charging described in the 5th section. Online charging requires an OCS and offline charging a CDF.
The 5G SA architecture describes a new “Converged Charging” architecture described in the 6th section.
Mobile roaming requires the exchange of charging information between the visited network and the home network directly or via clearinghouses. These charging information are in TAP format from 2G to 5G NSA. For 5G SA roaming, a new BCE (Billing Charging Evolution) charging architecture is required. TAP and BCE are described in the 7th section.

1. Charging in the 2G/3G circuit switched domain
1.1. Architecture of the 2G/3G circuit switched domain called R4
1.2. Prepaid charging: CAMEL
1.2.1. CAMEL Architecture
1.2.1.1. gsmSSF
1.2.1.2. gsmSCF
1.2.1.3. MAP (Mobile Application Part) and CAP (CAMEL Application Part) protocols
1.2.2. CAMEL Phase 1 for voice and CAP Phase 1
1.2.2.1. O-CSI
1.2.2.2. T-CSI
1.2.2.3. CAP Phase 1 Messages
1.2.2.4. Prepaid for outgoing and incoming call scenarios without and with roaming
1.2.3. CAMEL Phase 2 for voice and CAP Phase 2
1.2.3.1. O-CSI
1.2.3.2. T-CSI
1.2.3.3. CAP Phase 2 message
1.2.3.4. Prepaid for outgoing and incoming call scenarios without and with roaming
1.2.4. CAMEL Phase 3 for SMS delivery
1.2.4.1. O-SMS-CSI
1.2.4.2. T-CSM-CSI
1.2.4.3. CAP Phase 3
1.2.4.4. Prepaid for outgoing SMS scenarios without and with roaming
1.2.5. CAMEL Phase 3 for GPRS (Theoretical only)
1.2.6. CAMEL without and with roaming situation
1.3. Postpaid charging: mediation
1.3.1. Charging data record types
1.3.1.1. Mobile originated call (MOC) attempt
1.3.1.2. Mobile terminated call (MTC) attempt
1.3.1.3. Mobile originated emergency call attempt
1.3.1.4. Mobile originated call forwarding attempt
1.3.1.5. Roaming call attempt
1.3.1.6. Incoming gateway call attempt
1.3.1.7. Outgoing gateway call attempt
1.3.1.8. Transit call attempt
1.3.1.9. SS-actions
1.3.1.10. Location update VLR
1.3.1.11. Location update HLR
1.3.1.12. SMS MO
1.3.1.13. SMS MT
1.3.1.14. Terminating CAMEL call attempt
1.3.2. Offline charging and call flow scenarios

2. Online charging in the 2G/3G/4G/5G NSA packet switched domain: OCS
2.1. Online charging architecture: PCEF and OCS
2.2. Relationship between policy control and charging control
2.3. Basic DIAMETER protocol and DIAMETER applications
2.4. DIAMETER Gy interface for online charging
2.4.1. Credit Control Request/Credit Control Answer (CCR/CCA)
2.4.2. Re-Auth Request/Re-Auth Answer (RAR/RAA)
2.4.3. Online charging AVPs
2.5. Online charging procedures
2.5.1. Immediate event charging
2.5.2. Event charging with unit reservation
2.5.3. Session charging with unit reservation
2.6. Sy interface for subscription/notification of events relating to spending limits
2.6.1. Spending Limit Request/Spending Limit Answer (SLR/SLA)
2.6.2. Spending Status Notification Request/Spending Status Notification Answer (SNR/SNA)
2.6.3. Session Termination Request/Session Termination Answer (STR/STA)
2.6.4. Sy Procedures
2.7. Mobile data and associated call flows relating to policy and charging control (PCC)
2.7.1. Fair use
2.7.2. Blocked package
2.7.3. Prepaid
2.7.4. Anti bill shock
2.7.5. Shared data plan
2.7.6. International roaming pass
3. Offline charging in the 2G/3G switched packet domain: Charging Gateway Function (CGF)
3.1. Architecture of the 2G/3G switched packet domain called GPRS
3.2. CDR transfer: Ga interface and GTP protocol
3.2.1. Echo Message
3.2.2. Version Not Supported Message
3.2.3. Node Alive Message
3.2.4. Redirect Message
3.2.5. Data Record Transfer Message
3.2.6. S-CDR (SGSN-CDR)
3.2.7. G-CDR (GGSN-CDR)
3.3. GTP connection establishment procedure
3.4. CDR transfer procedure

4. Offline charging in 4G/5G NSA networks
4.1. Architecture of the 4G/5G NSA packet switched domain called EPC
4.2. Offline charging architecture: PCEF, OFCS
4.2.1. Gz interface
4.2.1.1. Accounting Request/Accounting Answer (ACR/ACA)
4.2.1.2. AVPs specific to ACR/ACA for mobile data charging
4.2.2. Offline charging scenarios

5. Charging in the IMS domain
5.1. IMS architecture
5.2. VoLTE, VoWiFi, EPS Fallback and VoNR
5.3. Online charging IMS
5.3.1. Online charging architecture
5.3.1.1. OCF
5.3.1.2. RF
5.3.1.3. ABMF
5.3.1.4. IMS-GWF
5.3.1.5. Ro, Rc and Re interfaces
5.3.1.6. Immediate event charging
5.3.1.7. Event charging with unit reservation
5.3.1.8. Session based charging
5.3.2. IMS online charging scenarios and call flows
5.4. Offline charging IMS
5.4.1. Offline charging architecture
5.4.1.1. CDF Charging Data Function
5.4.1.2. CGF: Charging Gateway Function
5.4.1.3. Billing System
5.4.1.4. CTF: Charging Transfer Function
5.4.1.5. DIAMETER RF interface
5.4.1.6. P-CSCF-CDR, S-CSCF-CDR, AS-CDR, IBCF-CDR, etc.
5.4.1.6.1. Accounting Request/Accounting Answer (ACR/ACA)
5.4.2. Charging header
5.4.2.1. P-Charging-Function-Addresses
5.4.2.2. P-Charging-Vector
5.4.2.3. IMS Charging Identifier (ICID)
5.4.2.4. Access network charging identifier
5.4.2.5. Inter-operator identifier (IOI)
5.4.3. IMS offline charging scenarios and call flows

6. 5G SA convergent charging : CHF
6.1. Architecture: NF/CTF, CHF
6.2. Offline charging
6.2.1. Event-based charging
6.2.2. Session-based charging
6.3. Online charging
6.3.1. Immediate event charging
6.3.2. Event charging with unit reservation
6.3.3. Session charging with unit reservation
6.4. Converged charging
6.4.1. Converged Event based charging
6.4.2. Converged Session based charging
6.4.3. Switch between quota managed and not quota managed
6.5. Convergent charging scenarios and call flows
6.6. Charging capabilities
6.6.1. 5G data connectivity charging
6.6.2. 5G SMS charging
6.7. Nchf service interface
6.7.1. Nchf_ConvergedCharging service
6.7.2. Nchf_SpendingLimitControl service
6.7.3. Nchf_OfflineOnlyCharging service
6.8. Bx interface to the Billing System
6.9. Charging Areas
6.9.1. Mobile data charging
6.9.2. SMS charging
6.9.3. Principles of slicing and charging of a network slice instance
6.9.4. 4G SA services exposed by the NEF and NEF charging

7. Charging in roaming situation
7.1. Role of clearinghouses
7.2. TAP: Transferred Account Procedures
7.2.1. TAP Procedures
7.2.2. CDRs for the different charging areas 2G to 5G NSA
7.2.3. TAP scenarios and call flows
7.3. BCE: Billing and Charging Evolution for charging in the context of 5G SA roaming