This TS defines a transport protocol for use in the IP multimedia (IM) Core Network (CN) subsystem
based on Diameter.
This TS is applicable to:
The Cx interface between the I-CSCF/S-CSCF and the HSS.
The Dx interface between the I-CSCF/S-CSCF and the SLF.
Whenever it is possible, this document specifies the requirements for this protocol by reference to specifications
produced by the IETF within the scope of Diameter. Where this is not possible, extensions to Diameter are defined
within this document.