AT&T SYSTEM 25 User Manual page 9

Ringing Tones
System 25 also signals you with
The rings and their descriptions
INSIDE CALL IIIIIIIIIIIIII (one long ring)
Your call is from a person inside your company.
OUTSIDE CALL IIIII IIIIII (two short rings)
Your call is from someone outside your company.
ABBREVIATED ALERT IIIII (one short burst of ringing)
This indicates a second call on another line, a busy-to-idle
reminder, a signal, or that your voice terminal is in program
mode.
PRIORITY RING IIIIIII IIIIII IIIIIIII (two short rings and
one long ring)
Your call is either a callback because the station or outside
line you requested is now available, or you call is being setup
remotely via Third-Party Setup (a data feature).
Lights
A steady red light identifies the line you are
using or the line you will be using when you
lift the handset.
A steady green light indicates that a line or
feature is in use.
A slow flashing green light indicates an
incoming call.
A fast winking green light indicates a call on
hold. (A green light that winks intermittently
indicates a call held temporarily while being
transferred or conference.)
On the Selector Console, a steady red light
indicates either that a voice terminal is off-
hook or that a call is parked on this extension.
On the Selector Console, a flashing red light
indicates a call to you from that voice terminal
or an unanswered call returning to your
console.
four distinctive rings.
are listed below.
5