Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Feasibility study on combined Circuit Switched (CS) calls and IP Multimedia Subsystem (IMS) sessions (V15.0.0; 3GPP TR 22.979 version 15.0
This document studies the service requirements associated with a multimedia service combining a CS call with one or more IMS services (or vice versa)@ while appearing as a single service to both end-users. The feasibility study addresses the high-level requirements and use cases such for combinational service including charging and user experience.