Section: 4.3.1.3 Charging Gateway Function
Content: The CDRs produced by the CDF are transferred immediately to the Charging Gateway Function (CGF) via the Ga reference point. The CGF acts as a gateway between the 3GPP network and the BD. It uses the Bx reference point for the transfer of CDR files to the BD. The entity relationship between the CDF and the CGF is m:1, i.e. one or more CDFs may feed CDRs into a single CGF. The CGF comprises the following main functions: - CDR reception from the CDF via the Ga reference point in near real-time. The protocols that may cross the Ga reference point are specified in TS 32.295[ Telecommunication management; Charging management; Charging Data Record (CDR) transfer ]  [54]. - CDR pre-processing: - Validation, Consolidation and (Re-) Formatting of CDRs. - CDR error handling. - Persistent CDR storage. - CDR routing and filtering, i.e. storing CDRs on separate files based on filtering criteria such as CDR type, CDR parameters, originating CDF, etc. - CDR File Management, e.g. file creation, file opening / closure triggers, file deletion. - CDR file transfer to the BD. For further details of those functions see TS 32.297[ Telecommunication management; Charging management; Charging Data Record (CDR) file format and transfer ]  [52].