Question: What triggers the eCall inactivity procedure in a mobile station?
Option 1: When the mobile station is in any MM Idle state except NO IMSI, NO CELL AVAILABLE or PLMN SEARCH.
Option 2: When the mobile station is in GMM-NULL or GMM-DEREGISTERED state and one of the timers T3242 or T3243 expires.
Option 3: When the mobile station receives a paging request from the network.
Option 4: When the mobile station is in any MM Idle state except NO IMSI, NO CELL AVAILABLE or PLMN SEARCH, and is in GMM-NULL or GMM-DEREGISTERED state, and one of the timers T3242 or T3243 expires.
Explanation: The eCall inactivity procedure is triggered when the mobile station meets specific conditions, including being in a certain MM Idle state, being in GMM-NULL or GMM-DEREGISTERED state, and having one of the timers T3242 or T3243 expire. This ensures that the mobile station enters the eCALL INACTIVE state only under specific circumstances, allowing it to conserve resources and maintain awareness of potential serving cells while ignoring paging requests.