Different Models of Charging

Actually Charging is based on different Charging Scenarios.

Basic Principles of OCS:

For online charging the basic structure follows a mechanism where the online client (CTF) requests resource allocation and reports credit control information to the OCS (Online Charging System). 

The online client implements the state machine described in RFC 4006 for "CLIENT, EVENT BASED" and/or "CLIENT, SESSION BASED".

a. For Immediate Event Charging (IEC), client uses the "CLIENT, EVENT BASED" state machine

b. For Event Charging with Unit Reservation (ECUR) it uses the "CLIENT, SESSION BASED" state machine for the first and final interrogations.

Three cases for control of users credit for online charging are:

• Immediate Event Charging (IEC)
• Event Charging with Unit Reservation (ECUR)
• Session Charging with Unit Reservation (SCUR)

In the case of IEC,  the credit control process for events is controlled by the corresponding CC-Requested-Type EVENT_REQUEST that is sent with Credit-Control-Request (CCR) for a given credit control event.

In the case of ECUR the CC-Request-Type INITIAL / TERMINATION_REQUEST are used for charging for a given credit control event, however,  where a reservation is made prior to service delivery and committed on execution of a successful delivery.

In SCUR,  the CC-Request-Type INITIAL / UPDATE and TERMINATION_REQUEST.