First Alert FA168C-CN User Manual page 22

Your system may have been programmed to use special keys to manually activate
emergency (panic) functions as follows:
This Function
Silent Alarm
Audible Alarm
Personal Alarm
Fire Alarm
*All panic functions send signals to the Central Monitoring Station, if connected.
To active a Panic Function:
Press and hold down for at least 2 seconds whichever
lettered key on the keypad has been programmed for
the desired emergency function.
OR
Press both keys of the assigned key pair at the same
time.
See your installer and use the chart provided in the Features Programmed in Your
System section to note the functions that have been programmed for your system.
Sends this signal*
silent alarm
audible alarm
auxiliary alarm
fire alarm
With This Sounding...
no audible alarm or any visual display
indicating that a silent alarm has been
initiated.
a loud, steady alarm at keypad(s) and
at any external sounders that may be
connected.
steady alarm sound at keypad(s), but
not at external bells or sirens.
temporal (pulsing) sound at external
bells and sirens.