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Proudly Presents
The MCI Telecommunications Glossary
Part I Volume IV (T - W)
Typed and edited by Knight Lightning
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- T -
T-CARRIER A time-division, pulse modulation, voice
carrier used on exchange cable to
provide short-haul trunks.
TAIL END HOP OFF (TEHO) In a private network, a call which is
carried over a flat rate facilities
(Intermachine Trunks or IMT) to the
closest switch node to the destination
of the call, and then connected into the
public network as a local call.
TANDEM A switching arrangement in which the
trunk from the calling office is
connected to a trunk to the called
office through an intermediate point.
TANDEM SWITCHING SYSTEM Synonym: Tandem Tie Trunk Network.
TANDEM TIE TRUNK NETWORK (TTTN) A serving arrangement which permits
sequential connection of tie trunks
between PBX/CENTREX locations by
utilizing tandem operation.
TANDEM TRUNKING Trunks which connects two or more
switches together.
TARIFF The published rates, regulations, and
descriptions governing the provisions of
communications service.
TELCO Local telephone company.
TELECOMMUNICATIONS The transmission of voice and/or data
through a medium by means of electrical
impulses and includes all aspects of
transmitting information.
TELEGRAPH A system employing the interruption of,
or change in, the polarity of DC current
signaling to convey coded information.
TELEPHONE A device which converts acoustical
(sound) energy into electrical energy
for transmission to a distant point.
TELETYPEWRITER A machine used to transmit and/or
receive communications on printed page
and/or tape.
TERMINAL (1) The device used at a subscriber's
location for purposes of communicating,
such as the telephone instrument,
teleprinter, computer terminal, etc.,
(2) The "end point" or extremity" such
as Terminal Pole of an open wire line,
or Terminal Office representing the
final central office in a switching
network where the subscriber's call
originates or terminates.
TERMINAL EQUIPMENT Devices, apparatus, and their associated
interfaces used to forward information
to a local customer or a distant
terminal.
TERMINATION (1) An item that is connected to the
terminal of a circuit or equipment.
(2) An impendance connected to the end
of a circuit being tested.
TIE-LINE A private line connecting two PBXs.
TIME DIVISION MULTIPLEXING (TDM) Equipment which enables the transmitting
of a number of signals over a single
path by transmitting them sequentially
at different instants of time.
TOLL CALL Any call to a point outside the local
service area.
TOLL CENTER (1) A central office where operators
(human or mechanical) are present to
assist in completing incoming toll
calls. (2) A center for the switching of
toll calls.
TOLL PLANT The facilities that connect toll offices
throughout the country.
TOLL RESTRICTION A restriction in outgoing trunks which
counts the first three digits dialed and
diverts calls to forbidden codes either
to a busy tone, to the operator, or to a
recorded announcement.
TOUCH-TONE ADAPTOR A device that can be connected to a
rotary dial telephone to allow for DTMF
signaling.
TRAFFIC Calls being sent and received over a
communications network.
TRAFFIC MEASUREMENT AND RECORDING A computer generated report showing usage
SYSTEMS (TMRS) usage information of telephone systems.
Usually this includes trunk utilization,
outages, queueing time, and the need for
additional common equipment.
TRAFFIC SERVICE POSITION SYSTEM A toll switchboard position configured
(TSPS) as a push button console.
TRANSMISSION The electrical transfer of a signal,
mesage or other forms of data from one
location to another without unacceptable
loss of information content due to
attenuation, distortion, or noise.
TRANSMISSION LEVEL The level of power of a signal normally
1,000 Hz, which should be measured at a
particular reference point.
TRANSMISSION SPEED Number of pulses or bits transmitted in
a given period of time, usually
expressed as Bits Per Second (BPS) or
Words Per Minute (WPM).
TRUNK A single circuit between two points both
of which are switching centers and/or
individual distribution points.
TRUNK GROUP An arrangement of communications
channels into an identical group.
TRUNK TYPE (TT) Trunks that use the same type of
equipment going to to the same
terminating location.
TRUNK UTILIZATION REPORT (TUR) A computer printout detailing the
traffic use of a trunk.
TWO-WIRE CIRCUIT 1. A channel for tranamitting data in
one direction at a time. 2. A short
distance channel using a single
send/receive pathway, usually 2 copper
wires, connecting a telephone to a
switch.
TELETYPEWRITER EXCHANGE SERVICE A service whereby a customer's leased
(TWX) teletypewriter is connected to a "TWX"
switchboard and from there connected
over regular toll circuits to
teletypewriter of any U.S. customer who
subscribes to a similar service.
- U -
UNIFORM CALL DISTRIBUTOR (UCD) A device located at the telephone office
or in a PABX which distributes incoming
calls evenly among individuals.
UNIFORM SERVICE ORDER CODE (USOC) The information in coded form for
billing purposes by the local telephone
company pertaining to information on
service orders and service equipment
records.
- V -
VALUE-ADDED NETWORK SERVICE (VANS) A data transmission network which routes
messages according to available paths,
assures that the message will be
received as it was sent, provides for
user security, high speed transmission,
and conferencing among terminals.
VIA NET LOSS (VNL) The lowest loss in dB at which a trunk
facility can be operated considering
limitations of echo, crosstalk, noise,
and singing.
VOICE CONNECTING ARRANGEMENT An interface arrangement provided by the
telephone company to accomodate the
connections of non-carrier provided
voice terminal equipment to the public
switched telephone network.
VOICE FREQUENCY (VF) Any of the frequencies in the band
300-3,400 Hz which must be transmitted
to reproduce the voice with reasonable
fidelity.
VOICE GRADE An access line suitable for voice,
low-speed data, facsimile, or telegraph
service. Generally, it has a frequency
range of about 300-3000 Hz.
VOICE GRADE FACILITY (VGF) A circuit designed to DDD network
standards which is suitable for voice,
low-speed data, facsimile, or telegraph
services.
- W -
WIDE AREA TELECOMMUNICATIONS A special direct distance dialing (toll)
SERVICE (WATS) service whereby a subscriber installs a
dedicated line arranged for either
inward or outward calls (not both)
between the customer's premises and a
specific gepgraphic area.
WIDEBAND A term applied to facilities or circuits
where bandwidths are greater than that
required for one voice channel.
WIRE CENTER The physical structure that house one or
more channel office switching systems.
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This concludes Part I Volume IV of the MCI Telecommunications Glossary. Look
for more G-philes on MCI by Knight Lightning coming soon to Metal Shop.
This has been a 2600 Club production
Thanx to Taran King
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