Question: What happens when a User Equipment (UE) attempts to edit the status of a priority level for fast call setup using the `+CFCS` command without having a subscription to that priority level?
Option 1: The UE will automatically enable the next available lower priority level for fast call setup.
Option 2: The UE will store the request and apply it once the subscription is activated.
Option 3: An `ERROR` or `+CME ERROR` result code is returned to the UE.
Option 4: The UE will default to using the highest available priority level for fast call setup.
Explanation: This is because, as per the specifications, if the user has no subscription to the priority level status they want to edit, an `ERROR` or `+CME ERROR` result code is returned, indicating that the requested action cannot be completed due to lack of subscription. This highlights the importance of subscription validation in telecom networks for specialized services like eMLPP (enhanced Multi-Level Precedence and Pre-emption).