AT&T System 25 - Manual (Page 71)

Signaling
❑
You can use a button to send an alert to another telephone
without actually calling that telephone.
Signaling Another Telephone
1 Do not lift the handset.
2 Press
SIGNAL .
Display
Sending a signal does not affect the display; however, when you
receive
a signal, the display shows the name of the person who
signalled you:
S I G A s a y , J
If no name is available, the display shows the extension of the
person who signalled you:
SIG 352
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