Question: In an IMS (IP Multimedia Subsystem) environment utilizing ICS (IMS Centralized Services), how is IMS service control enabled for a UE (User Equipment) that has not been enhanced for ICS?
Option 1: Through a direct SIP (Session Initiation Protocol) connection to the IMS core.
Option 2: Via an MSC (Mobile Switching Center) Server that has been enhanced for ICS.
Option 3: By utilizing SMS (Short Message Service) for control signaling.
Option 4: Through a transparent control channel established with the PS (Packet Switched) access network.
Explanation: For UEs not enhanced for ICS, enabling IMS service control requires intermediary support. An MSC Server enhanced for ICS acts as this intermediary, facilitating the necessary service control signaling between the non-ICS-capable UE and the IMS, thus ensuring continuity of IMS services even with legacy devices.