Radio supervision signal :

Supervision is a self-check of the entire intruder alarm system; except the key fob remote controls.
Whether the alarm is ON or OFF, each component of the system continuously sends a supervising signal to the control unit every 2–3 hours at regular intervals.

 
If the signal is not received from a component, the control unit reports a supervision fault, alerting the user of a possible component failure.
Press the Information button to view the control keypad display to identify the component in question.
This is why it is important to delete a removed component from the control unit when replacing a component.

A supervision fault signal is also generated if there is no telephone signal on a transmitter. In this case, the component that has been causing issues may need to be repositioned for better radio signal, or swapped out for a replacement.