AT&T SYSTEM 25 Manual page 172

The System Alarm feature provides an alarm on the attendant console to alert the attendant
to problems detected by the system software. When the green light next to the ALARM
button flashes, there is a problem with the System 25 software. If this occurs, the AT&T
Systems Technician should be notified at once.
If the flashing ALARM button is pressed, the light will change from flashing to steadily lit.
A new trouble situation will cause a steady light to start flashing again. Only when the
trouble has been corrected will the light turn off.
SLAC
If the console is beeping, this is an indicator from the display's alarm clock, not the
System Alarm. For more information about the alarm clock, see the entry for "Local
Display Functions" in the "Voice Terminal Features" section.
System Alarm
System Alarm 3-55