The Offline Charging System (OFCS) is a grouping of charging functions used for Offline Charging. It collects and
processes charging events from one or more CTFs, and it generates CDRs for subsequent offline downstream billing
The Offline Charging System is logically specified in TS 32.240.
The OCF consists of two distinct modules, namely the Session Based Charging Function (SBCF) and the Event Based
Charging Function (EBCF).
The Session Based Charging Function is responsible for online charging of network / user sessions, e.g. voice calls, IP
CAN bearers, IP CAN session or IMS sessions.
The Event Based Charging Function performs event-based online charging (also referred to as "content charging") in
conjunction with any application server or service NE, including SIP application servers.
Online charging is a mechanism where charging information can affect, in real-time, the service rendered and
therefore a direct interaction of the charging mechanism with session/service control is required.
The Online Charging System is specified in TS 32.296.