The Eclipse Merge online charging function is required to bill IP-based voice and media in real-time. The Eclipse Merge offline charging function is the default mechanism for billing voice and media; while not real-time, it can provide up-to-the-minute post-event termination.

Being able to bill IP voice and media in real-time with online charging allows for applications such as pay-as-you-go and credit limit setting to prevent subscribers from going far into debt.

Eclipse Merge Online Charging Function is a SIP Application Server. Subscriber profiles are set accordingly in the Home Subscriber Server (M-HSS); chargeable outgoing voice calls are then routed via the application server. The application server communicates with the billing system (M-MBP) using Diameter Accounting to charge the call in real-time and intercept the call when the balance has been exceeded. Eclipse Merge forward calls to the routing engine to allow the call to proceed to its destination.

Eclipse Merge Online Charging Function is also compatible with non-IMS SIP networks where it is used as a route point to provide call interception for pay-as-you-go-charging.

As the default mechanism for billing voice and media calls, the Eclipse Merge Offline Charging Gateway does not operate in realtime but can potentially do up-to-the-minute post-call termination.

For data charging, charging trigger points across the IMS network send in their requests to the Eclipse Merge Offline Charging Data Function. The Offline Charging Gateway Function provides persistent storage of CDRs until they can be retrieved by the CDR mediation process of the billing system.

The Offline Charging Data Function behaves as a Diameter Server accepting multiple connections from various IMS network elements. When a charging trigger function is fired one of two requests can be made:

SESSION-BASED CHARGING
A voice or video call (data stream) has a recorded duration and is a continual occurrence until the call is terminated. A start event will be followed with an end event and these timing details along with the call parameters are written to a CDR and pushed to the Charging Gateway Function.

EVENT-BASED CHARGING
A charging trigger function that does not require a session length to be billed can send an event record instead. The call parameters and the time the event took place are written as a call detail record and pushed to the Charging Gateway Function.

The Eclipse Merge Charging Gateway Function is a call detail record temporary repository. Call detail records (CDRs) are accepted from the Offline Charging Data Function. After the CDR has been received it is preprocessed for accuracy and then cached if validation is passed. The billing system will connect to the Charging Gateway Function or vice versa. Once the CDR is collected by the billing system that CDR is archived as a precaution and eventually removed.