The GSM/UMTS core network charging architecture and principles are specified in this TS, which thus provides an umbrella for other charging management TSs that specify:
the content of the CDRs per domain / subsystem /service (offline charging);
the content of real-time charging events per domain / subsystem /service (online charging);
the functionality of online and offline charging for those domains / subsystems / services;
the interfaces that are used in the charging framework to transfer the charging information (i.e. CDRs or charging events).
A set of domain/subsystem/service specific TSs covers the bearer (CS, PS, WLAN domains), subsystem (IMS) and service (MMS, LCS, etc.) levels, respectively, in the 32.25x, 32.26x and 32.27x TS number range. These TSs describe the mapping of the common architecture specified in this TS onto the specific domain/subsystem/service and the scenarios and information for online and offline charging that are specific to the domain/subsystem/service. They are commonly referred to as the "middle tier (charging) TSs".
A set of TSs in the 32.29x range covers common aspects such as CDR parameter and syntax descriptions, online and offline charging applications, and the charging interactions within the network (CDR transfer) as well as between the network and the Billing Domain (CDR file transfer).