AT&T System 25 - Manual (Page 5)

The Switchhook
The switchhook is the button held down by the handset when it
rests in the cradle on your telephone. Some System 25 features
require that you use the switchhook to signal the system.
When you are instructed to press the switchhook, press the
button down as far as it will go for approximately 1/2 second and
then release it. If the switchhook is released too soon, the signal
will not work. If you hold the switchhook down for too long
your call will be disconnected.
If you want to hang up and place another call right away, be
sure to hold down the switchhook for more than two seconds.
NOTE: If you have a
RECALL
or
FLASH
button on your
telephone, you can press it instead of the switchhook.
The
RECALL
or FLASH buttons cannot be used to disconnect a
call.
Ringing Tones
System 25 signals you with three distinctive rings. The rings
and their descriptions are listed below.
INSIDE CALL IIIIIIIIIIIIIIIIIIII (one long ring)
Your call is from a person inside your company.
OUTSIDE CALL IIIII IIIII (two short rings)
Your call is from the attendant or someone outside your
company.
PRIORITY RING IIIII IIIII IIIIIIIIII (two short rings and one long ring)
You are being alerted that your request for Callback can now be
completed; or a call is being set up remotely for your phone via
a data feature known as Third-Party Call Setup.
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