4.1 Charging mechanisms

32.2403GPPCharging architecture and principlesCharging managementRelease 18Telecommunication managementTS

4.1.0 General

3GPP networks provide functions that implement offline and/or online charging mechanisms on the domain (e.g. EPC), subsystem (e.g. IMS) and service (e.g. MMS) levels. In order to support these charging mechanisms, the network performs real-time monitoring of resource usage on the above three levels in order to detect the relevant chargeable events. The charging levels are further described in clause 5.3.

In offline charging, the resource usage is reported from the network to the BD after the resource usage has occurred. In online charging, a subscriber account, located in an OCS or CCS, is queried prior to granting permission to use the requested network resource(s).

Typical examples of network resource usage are a voice call of certain duration, the transport of a certain volume of data, or the submission of a MM of a certain size. The network resource usage requests may be initiated by the UE (MO case) or by the network (MT case).

Offline and online charging may be performed simultaneously and independently for the same chargeable event. Clause 5.5 provides further insight into potential utilisation of the charging information produced by the offline and online charging mechanisms.

4.1.1 Offline charging

Offline charging is a process where charging information for network resource usage is collected concurrently with that resource usage. The charging information is then passed through a chain of logical charging functions that are further explained in clause 4.3.1 and clause 4.3.3. At the end of this process, CDR files are generated by the network, which are then transferred to the network operator’s BD for the purpose of subscriber billing and/or inter-operator accounting (or additional functions, e.g. statistics, at the operator’s discretion). The BD typically comprises post-processing systems such as the operator’s billing system or billing mediation device.

In conclusion, offline charging is a mechanism where charging information does not affect, in real-time, the service rendered.

4.1.2 Online charging

Online charging is a process where charging information for network resource usage is collected concurrently with that resource usage in the same fashion as in offline charging. However, authorization for the network resource usage must be obtained by the network prior to the actual resource usage to occur. This authorization is granted by the OCS or CCS upon request from the network.

When receiving a network resource usage request, the network assembles the relevant charging information and generates a charging event towards the OCS or CCS in real-time. The OCS or CCS then returns an appropriate resource usage authorization. The resource usage authorization may be limited in its scope (e.g. volume of data or duration), therefore the authorization may have to be renewed from time to time as long as the user’s network resource usage persists.

Note that the charging information utilized in online charging is not necessarily identical to the charging information employed in offline charging.

In conclusion, online charging is a mechanism where charging information can affect, in real-time, the service rendered and therefore a direct interaction of the charging mechanism with the control of network resource usage is required.

4.1.3 Converged charging

Converged charging is a process where online and offline charging are combined. The charging information is utilized by CCS in one converged charging service which offers charging with and without quota management, as well as charging information record generation.