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Appendix 6: Glossary
Many of the terms in this glossary were defined with the assistance of Newton’s
Telecom Dictionary, by Harry Newton. To order a copy, call 1-800-LIBRARY or
write to: Telecom Library Inc., 12 West 21 Street, New York, New York 10010.
2500 set
The standard single-line touchtone desk telephone.
Abbreviated dialing
A feature of telephone systems that allows a caller to dial one or two digits to place a
call. The system translates the digits to the actual number being called. Also known as
“speed dialing”.
Busy Tone
A signal generated by the Central Office indicating that the line you are calling is busy.
Call Progress Tone
A tone sent from the switch to tell the caller of the progress of the call. Examples are
audible ringing, re-order, busy, timing, etc.
Central Office
Telephone company facility where subscribers’ lines are joined to switching
equipment for connecting other subscribers to each other, locally and long distance.
(Also called CO.)
Centrex
Business telephone service offered by a local telephone company from a local Central
Office. Centrex is leased to businesses as a substitute for a business-owned PBX or key
telephone system.
dB
A decibel is a unit of measure for expressing differences in signal strengths.
DTMF
Also called touchtone. Dual-tone multi-frequency. Push-button telephone signaling.
Factory Default
A setting programmed by Teltone. If necessary, you can change this value with one of
the programming commands. If necessary, use the Restore Defaults command to
return to factory defaults.
Forced disconnect
Method used by the telephone company to clear a line. When the called party goes
on-hook, the Central Office returns an open (that is, drops loop current) of at least 800
ms to the calling party. This is also known as Calling Party Control (CPC), or Cutoff on
Disconnect (COD).
Substation Line Sharing Switch
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