In fact this header is applicable to IMS networks using
the 3GPP charging architecture. Within this architecture there are many entities that
have the ability to generate charging records for the purpose of billing the subscriber
for services rendered. These entities include the various access points (SGSN/GGSN)
and the CSFCs within the network.
76 Chapter 3
The billing data is collected by one of two functions within the IMS charging architecture:
the event collection function (ECF) and the charging collection function (CCF).
These functions may be distributed throughout the network in a manner dependent on
the size of the network and the specific implementation. They are identified by their IP
addresses, and each of the network entities responsible for generating the billing data
for the charging functions is homed to one of the collection functions.
The use of this header is generally restricted to within the home network, or between
two trusted domains. Since it contains the addresses of the entities responsible for the
collection of billing data, it would not be in the best interest of the operator to allow this
information outside of its network. Therefore, the I-CSCF is responsible for deleting the
header prior to forwarding to another network.
The various entities that generate the billing data do so for sake of either postpaid
billing or prepaid billing.
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