Offline charging is used for network services that are paid for periodically. For example, a user may have a subscription for voice calls that is paid monthly. The Rf protocol allows an IMS Charging Trigger Function (CTF) to issue offline charging events to a Charging Data Function (CDF). The charging events can either be one-time events or may be session-based.

Converged Application Server provides a Diameter Offline Charging Application that can be used by deployed applications to generate charging events based on the Rf protocol. The offline charging application uses the base Diameter protocol implementation, and allows any application deployed on Converged Application Server to act as CTF to a configured CDF.

For basic information about offline charging, see RFC 3588: Diameter Base Protocol (http://www.ietf.org/rfc/rfc3588.txt). For more information about the Rf protocol, see 3GPP TS 32.299 (http://www.3gpp.org/ftp/Specs/html-info/32299.htm).