Question: What is a prerequisite for a User Equipment (UE) before it can initiate any Session Transfer procedures in an IP Multimedia Subsystem (IMS) environment?
Option 1: The UE must have an active multimedia session.
Option 2: The UE must be connected to both PS and CS access networks simultaneously.
Option 3: The UE must support both Single Radio Voice Call Continuity (SRVCC) and Dual Radio Voice Call Continuity (DRVCC).
Option 4: The UE must be IMS registered.
Explanation: According to the architectural requirements for IMS Service Continuity, a UE needs to be IMS registered before it can invoke any Session Transfer procedures. This ensures the UE is authenticated and authorized within the IMS network, allowing for seamless session management across different access networks.