The purpose of the real-time CDR
is to communicate the beginning of a session along with all of the session parameters,
and to then report on the progress of the session each time there is a change in the
session state.
For example, if another subscriber should be added to the session, this would be communicated
in another partial CDR containing the same session ID. The applications
can then correlate this CDR with the other, already-received CDRs for the same session
and update the status of the session within the application.
Charging in the IMS
The DIAMETER protocol consists of several messages used by the charging entities
to exchange charging event data. These messages are shown next. The DIAMETER
protocol itself is composed of base attribute-value pairs, or AVPs. Think of AVPs as
parameters within the DIAMETER message itself.
?– Accounting-Request (ACR)
?– Accounting-Answer (ACA)
?– Capabilities-Exchange-Request (CER)
?– Capabilities-Exchange-Answer (CEA)
?– Credit-Control-Request (CCR)
?– Credit-Control-Answer (CCA)
?– Device-Watchdog-Request (DWR)
?– Device-Watchdog-Answer (DWA)
?– Re-Auth-Request (RAR)
?– Re-Auth-Answer (RAA)
Offline The ACR and ACA messages are used for offline charging, while the remainder
of these messages are used for online charging. The parameters (or AVPs) for each of
these messages can be found in the following tables.
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