The interactions between the HSS (Home Subscriber Server) and the CSCF (Call Session Control Functions),
referred to as the Cx interface.
The interactions between the CSCF and the SLF (Server Locator Function), referred to as the Dx interface.
The interactions between the SIP Core and the SIP database, referred to as the Cx interface, for the Mission
Critical Services, where this interface is named as AAA-1, as described in TS 23.280.
NOTE: In the TS 23.280 the term SIP database is used for the HSS and the term SIP Core is used for
the P-CSCF, the I-CSCF and the S-CSCF when compared to this specification.