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The Dark Tower Phase II
<314> 432-0756
Proudly Presents
The MCI Telecommunications Glossary
Part I Volume III (O - S)
Typed and edited by Knight Lightning
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- O -
OFFERED TRAFFIC The number of call attempts in any
specified period of time.
OFF HOOK The condition which which results when a
telephone handset is lifted from its
mounting, allowing the hookswitch to
operate.
OFF NETWORK ACCESS LINE (ONAL) A connection from a private switched
service or transmission network accessing
the public switched network.
OFF NETWORK CALLING Telephone calls through a private
switching system and transmission network
which extend to the public telephone
system.
OFF PREMISES EXTENSION (OPX) An extension telephone or keyset that is
geographically separated from its
associated PBX.
ON HOOK The condition which results when a
telephone handset is placed on its
mounting, which causes the hook-switch to
open up its contacts.
ON NETWORK CALLING A term used to describe a call that
originates and terminates on private
network.
OPERATOR ASSISTED CALLS Non-DDD calls requiring manual
intervention.
ORIGINATING OFFICE The central office that serves the
calling party.
OTHER COMMON CARRIER (OCC) A company which provides long distance
telephone services, other than AT&T.
OUT-OF-BAND Any frequency outside the band used for
voice frequencies.
OUT-OF-BAND SIGNALING Use of a narrow band filters to place the
voice signal on a carrier channel below
3,400 CPS, reserving the 3,400 - 3,700
CPS band for supervisory signals.
OVERBUILD Adding radio capacity to a
telecommunications network.
OVERFLOW Switching equipment which operates when
the traffic load exceeds the capacity of
the regular equipment.
- P -
PAD A non-adjustable resistance network used
to insert transmission loss into a
circuit.
PHASE JITTER (See JITTER.)
POINT-TO-POINT A communications circuit between two
terminations which does not connect with
a public telephone system.
POLLING A progress by which a computer
interrogates the "readiness to transmit"
status outlying terminals.
PORT (See COMPUTER PORT.)
POSTAL TELEPHONE AND TELEGRAPH (PTT) Foreign government agencies responsible
for regulating communications.
PRIMARY AREA A customer"s local telephone calling
area.
PRIMARY ROUTING POINT The switch designated as the control
point for a longhaul telephone call.
PRIVATE AUTOMATIC BRANCH EXCHANGE/ A switching system that provides internal
PRIVATE BRANCH EXCHANGE (PABX/PBX) telephone communications between stations
located on a customer's premises as well
as between these stations and public or
private telephone networks.
PRIVATE LINE A dedicated communications path for use
between specific points.
PRIVATE LINE SERVICE Subscribers have dedicated, usually
full-time communications facilities.
Services can range from standard
communications lines to highly
sophisticated unique arrangements
tailored to a customer need. Channels
may be established between two points,
(e.g., tie together several customer
PABX's linking various locations.)
Subscribers may elect to purchase
transmission facilities and create
their own privately owned network.
PRIVATE USE NETWORK Two or more private line channels
contracted for by a customer and
restricted for use by the customer only.
PROGRAMMABLE READ ONLY MEMORY (PROM) Memory which is electrically programmed
by the equipment manufacturer into a
computer and can only be changed with
special equipment which erases the
previous program. Unaffected by power
loss.
PROGRAMMED SPEED DIALING Synonym: Abbreviated Dialing.
PUBLIC SWITCHED NETWORK (PSN) The nationwide network maintained by AT&T
and the independent telephone companies
which provide nationwide, unrestricted
telephone service.
PUBLIC UTILITY COMMISION (PUC)/ The state commisions regulating
PUBLIC SERVICE COMMISION (PSC) intrastate communications.
PULSE CODE MODULATION (PCM) The conversation of an analog signal to a
digital one through rapid sampling of the
signal amplitude (minimum 7,000 samples
per second). Provides undistorted
transmission, even in the presence of
noise.
PULSE-LINK REPEATER Connects one E&M signaling circuit
directly to another.
PUSH BUTTON DIALING Synonym: Dual Tone Multi-Frequency.
- Q -
QUEUE A temporary delay in providing service
caused by the inability of the system
provided to handle the number of messages
or calls attempted.
- R -
RADIO COMMON CARRIER (RCC) A communications common carrier that
provides radio paging and mobile
telephone services to the public.
RANDAM ACCESS MEMORY (RAM) That portion of a computer's memory which
can be accessed non-sequentially and,
therefore, is considered the "working
memory."
RATE CENTER A specified geographic location used by
the telephone company to determine
interchange mileage for rate.determina-
tion purposes.
READ ONLY MEMORY (ROM) That portion of a computer's memory which
is programmed electrically by the
manufacturer, is unchangeable, and is
unaffected by a power loss.
REDUNDANCY Duplicate equipment that is provided to
minimize the effect of failures or
equipment breakdowns.
REGENERATION The process of recieving distorted signal
pulses and from them recreating new
pulses at the correct repitition rate,
pulse amplitude, and pulse width.
REGIONAL OPERATING COMPANY (ROC) There are currently 7 ROC's which own 22
BOC's.
RE-HOMING A major network change which involves
moving customer services from one
switching center to another and
establishing the necessary trunking
facilities to do so.
REMOTE ACCESS The ability of transmission points to
gain access to a computer which is at a
different location.
REPEATER An electronic device used to amplify
signals which have become too weak.
REPEATING COIL The telephone industry's term for a
voice-frequency transformer.
RESELLER A business which buys services from one
business at a bulk rate and sells
portions of those services to multiple
users.
RESTORATION The re-establishment of service by
rerouting, substitution of component
parts, or as otherwise determined.
RETARD COIL A coil having a large inductance which
retards sudden changes of the current
flowing through its winding.
RINGBACK TONE Synonym: Audible Ringing Tone.
RINGDOWN A circuit or a method of signaling where
the incoming signal is actuated by
alternating current over the circuit.
ROTARY DIAL A rotary mechanism having a ten-hole
finger wheel which when wound up and
released causes pulsing contacts to
interrupt the line current and operate
the central office selecting equipment in
accordance with the digit dialed.
ROUTE GUIDE A map showing how a customer's calls are
routed.
ROUTE OPTIMIZATION Synonym: Least Cost Routing.
ROTARY HUNT An arrangement which allows calls placed
to seek out an ideal circuit in a pre-
arranged multi-circuit group and find the
next open line to establish a through
circuit.
- S -
SATELLITE COMMUNICATIONS A vehicle in geosynchronous orbit with
the Earth which contains a source of
energy, such as solar cells, and
amplifies the signals it recieves
before transmitting it back to Earth.
SECONDARY CARRIER Customer can override their primary
carrier selection on a call by call basis
and select other IC's to carry their long
distance traffic in equal access areas.
SELECTIVE CALLING The ability of a transmitting station to
specify by the use of assigned codes
which of several stations is to receive a
message.
SERVICE A group of circuits which terminate at
the same location and provide the same
capabilities.
SERVICE AND EQUIPMENT RECORD A list of equipment billed to customer by
type, quantity, monthly charge, location,
and billing dates.
SF SIGNALING (SINGLE-FREQUENCY) A signaling system which uses a 2,600 Hz
in-band signal on the voice path. The
tone is on in the idle condition, pulsed
for dialing, and off when the circuits is
in use.
SHORT HAUL Curcuits designated for use over
distances of 10 - 200 miles.
SIGNALING A procedure for indicating to the
receiving end of a communications circuit
that data is to be transmitted
SIGNALING CONVERTER A device with input and output signals
that contain the same information but
employ different electrical systems for
transmitting that information. Used at
the terminal of a trunk to convert the
equipment signals to the system used on
the trunk. Examples are: (1) ring down to
SF, (b) E&M to SF.
SIGNALING, IN-BAND A type of signaling using an AC signal
(usually a 2,600 Hz) within the normal
voice band. This signal can be trans-
mitted from and end to end of a long
voice circuit without any intermediate
signaling equipment. Since the signaling
is audibile, the signaling equipment must
be arranged for "tone on when idle"
operation.
SIMPLEX (SX) SIGNALING A signaling path over a dry talking
circuit which uses the two sides of the
circuit in parallel, derived by
connecting the midpoints of repeating
coils or retardation coils which are
across the circuit.
SINGLE SIDEBAND RADIO (SSB) A form of amplitude modulation of a radio
signal in which only one of the two
sidebands is transmitted. Either of the
two sidebands may be transmitted, and
the carrier may be transmitted, reduced
or suppressed.
SINGING A continued whistle or howl in an
amplified telephone circuit. It occurs
when the sum of the repeater gain exceeds
the sum of the circuit losses.
SOFTWARE (1) Any of the routines, programs, and
instructions required to use computers.
(2) A written statement of the
procedures to be used and the format of
the data at every step.
SPECIAL GRADE NETWORK TRUNK A trunk specially conditioned by
providing amplitudeand delay
equalization for the purpose of handling
special services such as medium-speed
data (600 to 2400 BPS).
SPECIALIZED COMMON CARRIER A new type of common carrier specializing
in providing transmission facilities.
(e.g., Microwave Communication Inc.(MCI),
Southern Pacific Communication Co.(SPC),
and the satelite communication companies
like Satellite Business System (SBS).)
SPEED NUMBER A one, three, or four digit number that
replaces a seven or ten digit telephone
X ] number. These numbers are programmed
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