Key telephone system
A telephone system in which the telephones have multiple buttons that permit a user to select outgoing or
incoming central office phone lines directly.
LED or light
Light-emitting diode. A semiconductor diode that emits light when a current is passed through it. Used for status
and information displays on electronic devices.
Loop start
One of two types of switched trunks (outside lines) typically leased from telephone companies, the other type
being “ground start”. A loop start trunk is seized by connecting a low resistance between the tip and ring (both
wires) of the telephone line.
If you need to find out if a line is loop start, call your telephone company.
Off-hook
The telephone is in an off-hook state when the handset is removed from the cradle. A modem or other device is
off-hook when it answers a call or when it seizes a line to initiate a call.
Public Switched Telephone Network (PSTN)
Usually refers to the worldwide telephone network accessible to all those with telephones and access privileges
(i.e., in the U.S., it was formerly called the Bell System network or the AT&T long-distance network.)
Remote
At a location physically removed from the equipment in question, that is, a computer or PBX system that can be
accessed by dialing through the telephone network.
Reorder Tone
A tone that sounds like the busy signal, but is twice as fast. It indicates that all switching paths are busy. If you
hear a reorder or “fast busy”, dial the number again.
Touch-tone
See DTMF.
Line Sharing Switch
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