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 Sh interface between an AS and the HSS.
The Sh interface between an SCS and the HSS.
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.