Question: During an IMS (IP Multimedia Subsystem) session, if a terminal's UICC (Universal Integrated Circuit Card) presence detection fails, what action is taken and within what timeframe?
Option 1: The IMS session remains active for at least 30 seconds before re-checking UICC presence.
Option 2: The IMS session is terminated as soon as possible but at least within 5 seconds after the failure detection.
Option 3: The terminal attempts to establish a new UICC-terminal interface within 10 seconds before terminating the session.
Option 4: Presence detection failure does not affect the ongoing IMS session.
Explanation: According to the specified behavior for handling UICC presence detection failures during an active IMS session, the session must be terminated promptly. The requirement to terminate the session 'as soon as possible but at least within 5 seconds' after detecting the failure ensures a balance between swift response to potential security or connectivity issues and allowing for any ongoing processes to gracefully exit. This approach helps maintain the integrity of the IMS service by preventing potential unauthorized access or misuse in the absence of a verified UICC.