Authorizing the services a subscriber is allowed is an important
function provided by the IMS.
We will not go into great detail on authorization in this section, since the focus here
is in the charging architecture and functions within the IMS specific to charging.
Accounting with DIAMETER
In order for billing systems to be able to accurately tabulate proper charges, billing
data must first be collected. The billing data is based on usage measurements for
the various services used by the subscriber. Usage measurements can be further
defined by the operator according to policy. For example, video services may follow a
per-movie fee rather than per-minute fee. Likewise, there may be flat rates for voice
calls.
There are two forms of usage measurements used to create charging records. Sessionbased
records are used for voice calls and data transfers. They are measured in terms
of duration and bandwidth requirements. This is analogous with how we are billed for
telephone calls today (minutes of use in most cases).
This does not mean that all operators must use session-based records. They are there
for operators to use if they choose this billing model, but they may choose to use event
records instead.
Event-based charging occurs for an event, such as a text message sent or received.
These measurements are basically peg counts. This is the simplest form of charging
and requires much less processing than session-based charging.
Pages:
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357