Section: 4.3.2.2.1 Online Charging Function
Content: 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 in the CS and PS domains may be performed using the CAP reference point from the MSC and SGSN, respectively, to the OCF (refer to TS 23.078[ Customised Applications for Mobile network Enhanced Logic (CAMEL) Phase 4; Stage 2 ]  [207] for details on CAP). Online charging communication between the S-CSCF and the SBCF is described in clause 4.3.2.2.2. All other network elements employ the Ro reference point for online charging (refer to TS 32.299[ Telecommunication management; Charging management; Diameter charging applications ]  [50]). Refer to TS 32.296[ Telecommunication management; Charging management; Online Charging System (OCS): Applications and interfaces ]  [53] for details on the relation between the network elements (i.e. the embedded online enhanced CTF) and the SBCF or EBCF, respectively.