IMS™ Application Server applications use the Ro online charging Web service to send authorization information to an Online Charging System (OCS). The Ro online charging Web service implements the operations required to perform online charging transactions. The operations allow an application to send session and event credit control charging information to the OCS. These operations are used to deplete quota from a subscriber's account while the service is being used.
The Ro online charging Web service interface is used for online charging and includes the ability to send Credit Control-Initial, Credit Control-Update, and Credit Control-Termination messages to an online charging server. It also has the ability to send a Credit Control-Event notification to the online charging server. Online charging can be used to interactively charge a subscriber while a service is being provided. For example, a subscriber may have purchased 200 minutes for access to an online gaming service. The service depletes the subscriber's quota as they use the service, and discontinues the service when the subscriber has used all 200 minutes. The DiameterImsRoApi defines the online charging transactions available through Web services.
In addition to the online event and session charging operations, the Ro online charging Web service interface also includes subscription and notification operations with which an IMS Application Server can subscribe to be notified when the CTF must reauthenticate with the OCS or when a reauthorization subscription expires.