Question: What action triggers a service subscriber's automatic disconnection from a Voice Group Call Service (VGCS)?
Option 1: Leaving the geographical area defined as the group call area
Option 2: De-selection/re-selection process initiated by the subscriber
Option 3: Switching to another voice call while still in the group call area
Option 4: Receiving a periodic notification message for a different VGCS
Explanation: A service subscriber is automatically disconnected from the call when they leave the defined group call area, ensuring only subscribers within the designated area can participate in the voice group call, maintaining the service's integrity and relevance based on geographical location.