Question: What is the primary purpose of the Initial IMS Charging Identifier (ICID) generated by an IMS node?
Option 1: To uniquely identify a device amongst all other devices for billing purposes.
Option 2: To facilitate IMS service continuity by tracking the initial SIP session.
Option 3: To authenticate users across different IMS services.
Option 4: To manage Quality of Service (QoS) for ongoing SIP sessions.
Explanation: The Initial IMS Charging Identifier (ICID) is specifically generated for the initial SIP session created for IMS service continuity. This indicates its primary role is to support continuous service provision, likely for charging and session management purposes related to the continuity of service, rather than device identification, user authentication, or QoS management.