Question: In IMS (IP Multimedia Subsystem) for non-ICS (IP Connectivity and Services) User Equipment (UE), how does the MGCF (Media Gateway Control Function) facilitate triggering of Communication Forwarding on No Reply (CFNRc) in the IMS domain?
Option 1: By mapping cause codes from the CS (Circuit Switched) leg to appropriate IMS error codes using the ICS indication.
Option 2: Through direct interaction with the UE, bypassing the need for ICS indications.
Option 3: By converting all incoming CS calls to IMS sessions before evaluating CFNRc conditions.
Option 4: Utilizing a predefined set of IMS error codes that mirror CS cause codes without needing an ICS indication.
Explanation: The MGCF leverages the ICS indication to translate CS leg cause codes into suitable IMS error codes, crucial for triggering CFNRc services within the IMS domain for non-ICS capable UEs, ensuring seamless integration and service provision across different network technologies.