Question: What happens to an Emergency Attached Mobile Station (MS) in PMM-IDLE state when its periodically assigned Reachability Area Update (RAU) timer expires?
Option 1: The MS initiates an immediate periodic RAU procedure to maintain connectivity.
Option 2: The Serving GPRS Support Node (SGSN) automatically extends the RAU timer to keep the MS emergency attached.
Option 3: The MS transitions from PMM-IDLE state to PMM-DETACHED state without initiating a periodic RAU procedure.
Option 4: The SGSN prompts the MS to perform an emergency re-attachment procedure.
Explanation: Upon expiry of the periodically assigned RAU timer, the Emergency Attached MS in PMM-IDLE state does not initiate a periodic RAU procedure. Instead, it transitions directly to the PMM-DETACHED state, highlighting a nuanced aspect of reachability management for emergency services.