IP Multimedia (IM) Subsystem Cx and Dx Interfaces; Signalling flows and message contents
This 3GPP Technical Specification (TS) specifies:
1. The interactions between the HSS (Home Subscriber Server) and the CSCF (Call Session Control Functions), referred to as the Cx interface.
2. The interactions between the CSCF and the SLF (Server Locator Function), referred to as the Dx interface.
3. 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 3GPP TS 23.280 [30].
NOTE: In the 3GPP TS 23.280 [30] 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.
The IP Multimedia (IM) Subsystem stage 2 is specified in 3GPP TS 23.228 [1] and the signalling flows for the IP multimedia call control based on SIP and SDP are specified in 3GPP TS 24.228 [2].
This document addresses the signalling flows for Cx and Dx interfaces.
This document also addresses how the functionality of Px interface is accomplished.
The Presence Service Stage 2 description (architecture and functional solution) is specified in 3GPP TS 23.141 [10].