OCSs

In the context of PCA deployment, OCS is referred to as Online Charging Server. OCSs are responsible for:

• Authorizing service, for example, granting or denying the services to the subscribers who requested the services via Diameter online charging signaling.
• Charging in accordance with service provisioned in real time based on accounting/metering
• Making the decision to terminate the service if certain conditions are met.

An OCS is selected by the OC-DRA function of PCA for an incoming session initiation message, for example, Gy/Ro CCR-I, using a load distribution algorithm. OC-DRA may store and maintain the session state for the subscriber to ensure all the in-session messages, for example, CCR-U and CCR-T, will be routed to the same OCS for online charging processing for this session. The relationship between the subscriber and the OCS lasts during the lifetime of the session.