Combined Circuit Switched (CS) and IP Multimedia Subsystem (IMS) sessions; Stage 1
The present document specifies service requirements for Combining CS and IMS services using a CS speech or CS multimedia call in association with an IMS session. The IMS session may consist of one or more IMS services.
Requirements for the following capabilities are included:
- Radio capability exchange.
- Terminal capability exchange.
- E.164 number exchange.
- Adding IMS session to an ongoing CS call.
- Adding a CS call to an ongoing IMS session.
- Supplementary services as they relate to CSICS.
It is intended that the capabilities defined herein for CSICS shall support interoperability between different operator networks, and roaming.