CAB
Carrier Access
Business
Cable
A cable is a group of metallic
conductors or optical fibers that are bound together, usually with a
protective sheath, a strength member, and insulation between individual
conductors/fibers and
for the entire group.
CABS
Carrier Access Billing System -
We fully explain what a Carrier Access Billing System is on this website. See
the main page of this website for more information.
CALC
customer access
line charges
CAP
competitive access
provider
Carrier
A carrier is a local (intra-LATA) or
long distance (inter-LATA) telecommunications service
providing organization. A waveform, pulsed or
continuous, that is modulated by another
information bearing waveform.
Carrier System
A carrier system is a transmission
system for transmitting one or more channels of information by
processing and converting to a form suitable for the transmission medium used.
Carrier systems
are classified as either analog carrier systems or digital carrier systems.
CBR
continuous bit
rate
CCIS
common-channel
interoffice signaling
CCITT
CCITT is the
International Consultative Committee for Telephone and Telegraph, a
consultative committee to the International Telecommunications Union (ITU) which recommend international standards for telephone and telegraph services and facilities to aid
international connectivity and interoperability.
CCSA
common-control
switching arrangement
CCS
centi-call seconds or common-channel
signaling
CDMA
code division
multiple access
Cell Relay
Call relay is the
process of transferring data in the form of fixed length packets called cells.
Cell relay is used in high-bandwidth, low-delay, packet-like switching and
multiplexing techniques. The objective is to develop a single multiplexing/switching mechanism for
dividing up usable capacity (bandwidth) in a l-manner that supports its
allocation to both isochronous (e.g., voice and video traffic) as well as packet data communications services. Standards
groups have
debated the optimum cell size. Small cells favor low delay for isochronous
applications but involve a higher header to user information overhead penalty than would be needed for
most data applications. The current CCITT specification for BISDN is for a 53-byte cell
which includes a 5-byte header and a 48-byte payload.
Centi Call Seconds (CCS)
CCS is a unit of
the average traffic intensity of a facility during a period of time, a CCS is
100 call
seconds of traffic during one hour. Therefore a single traffic source, e.g.,
one call that generates
traffic 100% of the time produces 36 CCS of traffic per hour, i.e., 3600
seconds of traffic every
3600 seconds. An equivalent amount of traffic could also be generated by 10
sources that only generate traffic 10% of the time. That is, 10 sources of traffic generating 3.6
CCS each, contributes the same total traffic as a single 36 CCS traffic source. An
alternative measure for traffic is erlangs where 1 erlang equals 36 CCS.
CENTRal EXchange (Centrex)
Centrex is a
LEC-provided switching service for business customers that permits
station-to-station
dialing, listed directory number service, direct inward dialing and station
number identification on outgoing calls. The switching functions are usually performed in a central
office. Digital Centrex offers the advanced features of fourth generation PBXs, without the need to
purchase or lease equipment and, in most cases, eliminates the need for floor space, electrical
prime power and
heating, ventilation and air conditioning.
Central Offices (CO)
A central office
is a telephone company building in which network equipment such as
switches are installed.
Channel
A channel is a single communications
path in a transmission medium connecting two or more points in a network, each path being separated by some means; e.g., spatial or
multiplex separation, such as frequency or time division multiplexing.
"Channel" and "circuit" are often used interchangeably, however circuit can also
describe a physical configuration of equipment that provides a network transmission capability for multiple channels. The characteristics
of
channels and circuits are determined by the network equipment and media used to
support them.
Channel Service Unit
(CSU)
Channel Service
Units (CSUs) and Data Service Units (DSUs) are required to connect digital customer premises equipment (CPE) to carrier networks. A CSU is network channel
terminating equipment (NCTE) attaching as CPE to telephone company's digital circuits, and
protecting the network from harm. Other CSU functions include line conditioning and
equalization, error control (e.g., bipolar signal violations), and the logical ability to respond to local
and network loop back
circuit testing commands. See Data Service Units (DSU).
Circuit Associated
Signaling
Circuit Associated
Signaling is a technique that uses the same facility path for voice and
signaling traffic. Historically this approach was selected to avoid the costs of separate
channels for signaling and because the amount of traffic generated by signaling is small
compared to voice, minimizing the chance for mutual interference. Circuit associated signaling can
be contrasted with some common-channel signaling systems that use completely separate packet
switched networks for signaling traffic.
Circuit Switching
Circuit switching
is a process that establishes connections on demand and permits the
exclusive use of those connections until released. Packet and message switching,
primarily used in data communications networks are alternative switching techniques.
City Wide Digital
Centrex
A city wide digital centrex is a capability to serve multiple business
locations within a single NXX (exchange code), using multiple LEC central office Centrex switches. Outside
callers are unaware that multiple business locations are involved.
CLEC
Competitive Local
Exchange Carrier, most commonly referred to as Competitive Local Exchange
Carrier.
CLLI
Common Language
Location Identifier
CMIP
common management
information protocol
Coaxial Cable
Coaxial Cable
(also called coax cable or coax) consists of an insulated central
conductor surrounded by a second cylindrical conductor that is clad with an insulating
sheath. The outer conductor usually consists of copper tubing or copper braid.
COC
central office
connections
Codec
Codec is a
contraction of coder and decoder; a device that encodes analog signals into
digital signals, for transmission through a network in digital format, and decodes
received digital signals back into analog signals.
Common Channel
Signaling (CCS)
CCS is a signaling
system developed for use between stored program control digital switching systems, in which all of the signaling information for one or more trunk groups
is transmitted over a dedicated signaling channel, usually, but not always completely separate
from the user traffic bearing facilities.
Common Management
Information Protocol (CMIP)
CMIP is the OSI
protocol for network management. A structure for formatting messages and transmitting information between reporting devices (agents) and data collection programs, developed by the International Standards Organization and designated ISO/IEC
9596.
Communications
Communications is
the process of representing, transferring, interpreting or processing information (data) among persons, places, or machines. Communications implies a
sender, a receiver, and a transmission medium over which the information travels. The
meaning assigned to the data must be recoverable without degradation.
Conditioning
Conditioning is an
adjustment made to the electrical characteristics of a cable pair to improve
its performance for a specific use.
Conductor
In electrical
circuits, a conductor is any material that readily permits a flow of electrons
(electrical current) through itself. Analogously, optical fibers are sometimes said to
conduct light waves and are also referred to as conductors.
Corporation for Open
Systems (COS)
COS is a nonprofit
organization composed of manufacturing, service, and user organizations
in the computer communications area. Seeks to facilitate the development of the
international, multi-vendor marketplace through the development, introduction, and
verification of OSI and ISDN standards and by ensuring vendor equipment interoperability.
CO
central office
CPU
central processing
unit
Cross Connect
1.in a premises
distribution system, equipment used to terminate and administer
communications circuits. In a wire cross connect, jumper wires or
patch cords are used to make circuit connections, between horizontal and backbone wiring segments. 2. in transmission systems a patch panel for connecting circuits.
CSDC
circuit-switched
digital capability
CSMA/CD
Carrier sense
multiple access with collision detection; a local area network contention
based access control protocol technique by which all devices attached to the network
"listen" for transmissions in progress before attempting to transmit themselves and, if two
or more begin transmission simultaneously, are able to detect the "collision". In
that case each backs off (defers) for a variable period of time (determined by a preset algorithm)
before again attempting
to transmit. (Defined by the IEEE 802.3 standard).
CSR
Centrex station
rearrangement
CSU
channel service
unit
Customer Premises
Equipment
Customer Premises
Equipment is all telecommunications terminal equipment located on the customer premises. except coin operated telephones.
D type Channel Bank
A D type channel
bank is channel termination equipment used for combining (multiplexing)individual analog channel signals on a time division basis. D type channel
banks provide interfaces for "n" analog signal inputs. Each analog input signal is
directed to a codec for en coding to PCM samples. A part of a Tl carrier system.
DACS
digital access
& cross-connect system
DARPA
Defense Advanced
Research Projects Agency
Data Compression
Data compression
is a technique that removes redundancy in transmitted bit patterns to
reduce transmission rates by 20% to 200%. For example, a modem designed to send and
receive data at 1200 bps without data compression may be capable of supporting 2400 bps with
data compression, using the same network analog voice-grade channel.
Data Service Units (DSU)
DSUs are channel service units (CSI's) and data service units (DSUs)
are required to connect digital customer premises equipment (CPE ) to carrier networks. A hardware device providing an interface between a digital line and a unit of data terminal equipment. DSUs provide transmit and receive control logic, synchronization and timing recovery across data
circuits. DSUs may also
convert ordinary binary signals generated by CPE to special bipolar signals.
Bipolar signals are
designed specifically to facilitate transmission at up to 1.544 Mbps rates over
UTP cable, a media originally intended for 3 kHz, voice bandwidth signals. See Channel Service
Units (CSU).
Data Terminal Equipment
(DTE)
DTE is any device
that can send data, receive data or perform both functions. (Note:
sometimes DTE implies digital terminal equipment, a type of CPE used with digital
Service--see CSU and
DSU.)
DB Loss
Decibel (dB) is a
unit of measure of signal strength, usually the relationship between a transmitted signal and a standard signal source. Loss is measured when the
signal received across a communication circuit is less than what was transmitted by the signal
generator.
DCE
data circuit
terminating equipment
DCP
digital
communications protocol
DCS
digital
cross-connect system
DDD
direct distance
dialing
DDN
Defense Data
Network
Digit L
Digital L is another
amplitude condition that represents a binary digit 0. See binary digit or bit.
Digital Carrier Systems
Digital Carrier
Systems are carrier systems for digital signals that uses regenerative versus
linear repeaters and time division multiplexing.
Digital Cross Connect
System (DCS)
DCS is a new
generation of switching/multiplex equipment that permits per-channel DS0
(64
kbps) electronic cross-connection from one T1 transmission facility to another,
directly from the
constituent DSl signals. Commonly referred to as
"DACS" (digital access and cross connect system), although this is a trademark of AT&T.
Digital Signal
A digital signal
is a signal (electrical or otherwise) in which information is carried in a
limited
number of different (two or more) discrete states. The most fundamental and
widely used form of the digital signal is binary, in which one amplitude condition represents a
binary.
Digital Termination
Service (DTS)
DTS is a service
provided by some carriers permitting opera tors of
private networks to use digital microwave equipment to gain access to carrier net works. The FCC has
allocated a special microwave band for DTS.
Direct Inward Dialing
(DID)
DID is
PBX-to-central office trunks that allow incoming calls to a PBX to ring
specific stations without attendant assistance. DID greatly reduces the
number of required console attendants, compared with systems in which all calls must be extended by console
attendants.
Direct Outward Dialing
(DOD)
DOD is
PBX-to-central office trunks that allow outgoing calls to be placed directly by
PBX stations.
Dispersion
In dispersive
media, dispersion are complex signals are distorted
because the various frequency components which make up the signal have different propagation characteristics
and paths. Due to the finite conductivity of copper, wire or cable media for guided wave
transmission is fundamentally dispersive. Dispersion limits the upper bit rate that a medium
can support by distorting the signal waveforms to the extent that transitions from one
information state to another cannot be reliably detected by receiving equipment, (e.g., logical l
logical 0 value
changes).
DLCI
data link
connection identifier
DOD
direct outward
dialing
DQDS
distributed queue
dual bus
DS"N" Digital
Signal Hierarchy
A time division multiplexed
hierarchy of standard digital signals used in telecommunications systems. DS1 level in the hierarchy corresponds to a 1.544 Mbps TDM signal
which comprises 24 DS0 signals. DS0 refers to individual digital signals at channel rates of 64
kbps. Four DS1 signals digitally multiplexed produce a DS2 level signal, containing 96 DS0 channels,
and requires a transmission medium that supports 6.312 Mbps. A DS3 level signal results from
the digital multiplexing of 7 DS2 signals, supports 672 DS0
signals and requires a 44.736 Mbps transmission medium. Finally a DS4 level signal supports 6 DS3 level signals, 4032 DS0
signals and requires a 274.176 Mbps transmission medium. The DS hierarchy accounts for non synchronism
in the multiplexing plan, hence the term "asynchronous digital hierarchy"
and the use of overhead bits. Note that bit rates at higher levels are not integer multiples of 64 kbps.
DSP
digital signal
processor
DSS/BLF
direct station
selection/busy lamp field
DSS
digital subscriber
service
DSU
data service unit
DTMF
dual tone multiple
frequency
DTS
digital
termination service
Dual-Tone Multiple
Frequency (DTMF)
the generic name
for the tone signaling scheme used to signal from telephones to switching equipment, in which 10 decimal digits and two auxiliary characters are
represented by selecting two frequencies of the following group: 697, 770, 852, 941,1209,1336,1447 Hz.
E&M Leads Signaling
E&M Leads
Signaling is an interface, used for connections between switches and
transmission systems and between transmission systems themselves. Signaling information is
transferred across the interface via 2-state voltage conditions on two leads, each with a
ground return, separate from the leads used for message information. The message and signaling
information are combined and separated by means appropriate to the transmission facility.
E-mail electronic mail
electronic mail
ECSA
Exchange Carriers
Standards Assoc
EKTS
electronic key
telephone system
Electrical Signal
An electrical
signal is a signal consisting of an electrical current (i.e., a flow of
electrons) that varies with time or space in accordance with specified parameters.
Electronic Mail
Electronic mail is
a generic term for non-interactive communication of text, data, image or
voice messages between a sender and designated recipients using telecommunications.
Electronic Switched
Network (ESN) Service
ESN service is a
private network service that provides user organizations with a uniform numbering plan and numerous call-routing features. The electronic tandem
switching functions are furnished by either PBX or Centrex switching equipment.
EMI
electromagnetic
interference; also, exchange message interface
End Office (EO)
EO is a LEC (BOC
or an ITC) switching system within a LATA where local loops to customer stations are terminated for purposes of interconnection with each other and
with trunks. CO (central office) and EO are often used interchangeably.
Entrance
Facilities
1. in a
premises distribution system, the point of interconnection be tween the building wiring system and external telecommunications facilities (LEC networks, other
buildings, etc.). Bellcore defines the interface with LEC networks as end-user points of termination
(POT). 2. has a further specific meaning in interstate access, entrance facilities for interstate
access (ENFIA).
EO
end office
EPSCS
enhanced private
switched communications service
Equipment Room
In a premises
distribution system, an equipment room is a special purpose room(s), with
access to the backbone wiring, for housing elecommunications,
data processing, security, and alarm
equipment.
erlang
An erlang is an international dimensions unit of the average
traffic intensity of a facility during a period of time; one erlang of traffic is equivalent
to a single user who uses a single resource 100% of the time. See centicall seconds.
ESF
extended superframe
ESN
electronic
switched network
Exchange Carrier (or
local exchange carrier LEC)
An exchange
carrier is any company, BOC or independent which provides intra-LATA telecommunications within its franchised area.
Extended Superframe Format (ESF)
ESF is an
extension of the superframe format of T1 carrier
systems from 12 to 24 frames and the use of framing bits for error checking, a facilities data link (FDL) as well as
frame synchronization. See superframe format.
Facilities Based
Private Switched Network Services
Facilities Based
Private Switched Network Services is a private network for which LECs and IXCs dedicate physical switching and transmission facilities for the exclusive use
of a particular customer.
Fast Packet
Fast Packet is a
term referring to a number of broadband switching and networking
paradigms. Implicit is the assumption of an operating environment that includes reliable,
digital, broadband, nearly error free transmission system.
FCC Federal
Communications Commission
The FCC is a board
of commissioners empowered by the U.S. Congress to regulate all
interstate and international communications, as well as use of the radio frequency media. www.fcc.gov
FDDI
fiber-distributed
data interface
FDL
facility data link
FDM
frequency division
multiplexing
FEP
front-end
processor
FIPS
Federal
Information Processing Standard
Foreign Exchange (FX)
FX is a service
that provides a circuit(s) between a user station, a PBX, or a Centrex switch,
and a central office other than the one that normally serves the caller.
Frame
In time division
multiplexing systems, Frame is a sequence of time slots each containing a
sample from one of the channels carried by the system. The frame is repeated at
regular intervals, (normally the sampling rate used in analog-to-digital conversion processes for
signals being multiplexed) and each channel usually occupies the same sequence position in
successive frames.
Frame Relay
Frame relay is a
network interface protocol defined in CCITT Recommendation 1.122
"Framework for additional packet mode bearer services," as a packet mode service. In
effect it combines the statistical multiplexing and port sharing of X.25 packet switching with the
high speed and low delay of time division multiplexing and circuit switching. Unlike X.25, frame
relay implements no layer 3 protocols and only the so-called core layer 2 functions. It is a
high-speed switching
technology that achieves ten times the packet throughput of existing X.25
networks by eliminating two-thirds of the X.25 protocol complexity The basic units of information transferred are variable length frames, using only two bytes for header information. Delay
for frame relay is lower than for X.25, but it is variable and larger than that experienced in
circuit switched networks. This means that currently frame relay is not suitable for voice and video
applications where excessive and variable delays are unacceptable.
Frequency
Frequency is
acoustic waves and electrical signals might be made up of only a single tone,
like a single note on a piano. In this case the signal waveform is made up of repeating
identical "cycles" and is said to be of a single frequency, equal to the number
of cycles that occur in one second of time. In communications, frequency was traditionally expressed in
cycles per second, but is now expressed in hertz (Hz), still equal to one cycle per second. Thus,
one thousand cycles per second is equal to one thousand hertz, or a kilohertz (kHz).
Frequency Division
Multiplexing (FDM)
FDM divides the
frequency bandwidth (spectrum) of a broadband transmission circuit into
many subbands, each capable of supporting a single, full
time communications channel on a non-interfering basis with other multiplexed channels. FDM multiplexing is
generally suitable for use with analog carrier transmission systems.
FSS
fully separated
subsidiary
FTAM
file transfer
access & management
Full Duplex
Full duplex is a
transmission path capable of transmitting signals in both directions
simultaneously.
FX
foreign exchange
GOSIP
Government Open
Systems Interconnection Profile
Grade Of Service (GOS)
GOS is an estimate
of customer satisfaction with a particular aspect of service such as
noise, echo or blocking. For example the noise grade of service is said to be 95% if,
for a specified distribution of noise, 95% of the people judge the service to be good or
better. In traffic networks, GOS defines the percentage of calls that receive no service
(blocking) or poor service (long delays). GOS measures apply to all aspects of telecommunications
networks. In many cases the literature equates GOS only with the probability of a blocked call. When
used without further explanation, GOS generally refers to blocking probability.
Ground Start
Ground start is a
supervisory signal given at certain coin telephones and PBXs by connecting
one
side of the line to ground.
Guided Media
Guided media is
media that constrain electromagnetic or acoustic waves within boundaries established by their physical construction. Examples include paired metallic
wire cable, coaxial
cable, and fiber optic cable.
Half Duplex
Half duplex is a
transmission path capable of transmitting signals in both directions, but only
in
one direction at a time.
HDLC
high-level data
link control
Header
The header is
control information appended to a segment of user data for control, synchronization,
routing and sequencing of a transmitted data packet or frame.
Hertz (Hz)
Hertz is the
measurement that distinguishes electromagnetic waveform energy; number of cycles, or complete waves, that pass a reference point per second; measurement
of frequency, by which one hertz equals one cycle per second.
Horizontal Wiring
In a premises
distribution system, horizontal wiring is the connection between the telecommunications outlet in work areas and the telecommunications closet.
Hub
In local area networks
(LANs), a hub is a wiring concentrator equipment used
in hierarchical star physical wiring topologies. Those directly connected to terminals or other user
devices are of ten referred to as local hubs or concentrators. Central hubs are those at the highest
hierarchical level. Hubs often provide the means for interconnecting 10BaseT, coaxial or
fiber optic cable LAN segments. Intelligent hubs may implement multiport bridging and network management
functions.
HVAC
heating,
ventilation and air conditioning
I-MAC
isonchronous media access controller
IDN
integrated digital
network
IEC
International Electrotechnical Commission
Impairments
Impairments is the
(e.g., transmission channel and signal impairments) degradation caused by practical limitations of channels, (e.g., signal level loss or attenuation,
echo, various types of signal distortion, etc.) or interference induced from outside the channel (such
as power-line hum or interference from heavy electrical machinery). The measurement of transmission
impairments is an important aspect of predicting whether or not telecommunications systems
will sustain the
business applications they are intended to support. Signal-to-noise ratio,
percent distortion, frequency response, and echo are measurements that define impairments most
noticeable by users in analog voice systems.
Inbound Signaling
Inbound signaling
uses not only the same channel path as the voice traffic, but the same
frequency range (band) used for the voice traffic.
Independent Telephone
Company (ITC)
ITC is a local
exchange carrier that is not one of the 22 divested Bell-operating companies. ITCs are not generally subject to the restrictions of the MFJ, although some of the
larger ones are bound by separate consent decrees.
Southern New England
Telephone and Cincinnati Bell
are generally considered ITCs from a regulatory point of
view.
Integrated Services
Digital Network (ISDN)
ISDN consists of a
set of standards being developed by the CCITT and various
U.S.
standards setting organizations. The CCITT formal recommendations, adopted in October,
1984, first defined ISDN as ". . . a network, in general evolving from a telephony integrated digital network, that provides end-to-end digital connectivity to support a wide range of
services, including voice and non-voice, to which users will have access by a limited set of standard
multipurpose user-
network interfaces." The concept of user access to an existing integrated
digital network (IDN) underlies the ISDN.
Inter-LATA Services
Inter-LATA
services are revenues, functions, etc., that relate to telecommunications
originating in one LATA and terminating outside that LATA. An interexchange carrier (IXC) is a company which provides
telecommunications services between LATAs. (the domain of IXCs).
Intermediate Cross
Connects
In a premises
distribution system, intermediate cross connects are cross-connects
located
telecommunications closets.
International
Organization for Standardization (ISO)
ISO is a worldwide
federation of national standards bodies (ISO National Bodies). The work
of preparing international standards is normally carried out through ISO technical
committees. Draft proposals for international standards adopted by the
technical committees are circulated to the National Bodies for approval
before their acceptance as Draft International Standards by the
committee.
Internet
The internet is a
large collection of connected networks, primarily in the
United States
, running the Internet suite of protocols. Sometimes referred to as the
DARPA Internet, NSF/DARPA In ternet, or the Federal Research Network.
Internet suite of
protocols
The internet suite of protocols is a
collection of computer-communication protocols originally developed under DARPA sponsorship, including the transmission control
protocol/internet protocol (TCP/IP).
Interoffice Channel
In LEC tariffs, Interoffice Channel
is the channel connecting two serving COs (more accurately serving wire centers). In IXC tariffs, the channel connecting
two serving IXC POPs, interoffice transmission facilities used to connect LEC switching systems.
Intra-LATA
Intra-LATA are
services, revenues, functions, etc., that relate to telecommunications
originating
and terminating within a single LATA (the domain of LECs).
IOC
interoffice channel
IPX
internetwork packet exchange
IP
internet protocol
ISDN
integrated
services digital network
Isochronous Signals
Isochronous
Signals are periodic signals in which the time interval that separates any
two corresponding significant occurrences or level transitions is always equal to
some unit interval or a multiple of that unit interval. For example, in digitized voice signals,
ideally voice samples occur isochronously at precisely the sampling
interval or frame rate. Packet data signals are not isochronous.
ISO
International
Organization for Standardization
ITC
independent
telephone company
ITU
International
Telecommunications
Union
IVR
integrated voice
response
JPEG
Joint Photographic
Experts Group
JTM
job transfer
manipulation
Key Telephone System
(KTS)
KTS is an
arrangement of multi-line telephones and associated equipment that permits
the station user to depress buttons (keys) to access different central office or
PBX lines, as well as to perform other functions. Typical functions include answering or placing a call
on a selected line, putting a call on hold, using the intercom feature between phones at the same
location, or
activating a signal buzzer.
KSU
key service unit
KTS
key telephone
system
LAN (IEEE 802.3
10BaseT)
LAN (Local Area
Network) is an Institute of Electrical and Electronic Engineers specification
for a class of LANs using four-pair unshielded twisted pair (UTP) cable. See Local
Area Network.
LAN
local area network
LATA
local access and
transport area
LCR
least-cost routing
LDN
listed directory
number; generally an organization's main telephone number that appears in
the
telephone book.
LDN
listed directory
number
LEC
local exchange
carrier
Line
See loop transmission
facilities.
Local Access And
Transport Area (LATA)
LATA is a
geographic area (called an "exchange" or "exchange area" in
the MFJ) within each BOC's franchised area that has been established by a
BOC in accordance with the provisions of the MFJ for the purpose of defining the territory within which a BOC may offer
its telecommunications services. In 1989, there were 198 LATAs,
also referred to as market service
areas (MSAs), in the
United States
.
Local Area Network
(LAN)
LAN is a premises
high-speed (typically in the range of 10 Mbps) data communications system wherein all segments of the transmission medium (typically coaxial cable,
twisted pair or optical fiber) are contained within an office or campus environment.
Local Channel
In LEC tariffs, a
local channel is the local loop that connects customer premises to serving
LEC wire centers. In IXC tariffs, the network components (transmission, switching,
other) used to connect customer premises to serving IXC POPs.
Loop Length
Typically, loop length is a complete
electrical circuit; the pair of wires that winds its way from the central
office to the telephone set or system at the customer's premises.
Loop Signaling
Loop
signaling is a method of signaling
over dc circuit paths that utilizes the metallic loop formed by the line or trunk conductors and terminating circuits.
Loop Start
Loop
start is a supervisory signal
given at a telephone or PBX in response to closing the loop's DC current path.
Loop Transmission
Facilities
Loop
transmission facilities connect
switching systems to customer premises equipment throughout the serving area. A loop is a transmission path between a customer's
premises and a LEC central office. The most common form of loop, a pair of wires, is also
called a line. A loop" can be derived from digital loop carrier (DLC) systems also referred to as
subscriber loop carrier (SLC) systems.
LSI
large-scale
integrated circuit
MAAP
maintenance &
administration panels
MACSTAR
multiple access
customer station rearrangement
MAC
media access
control or moves, adds, and changes
Main Cross-Connects
In a premises
distribution system, main cross-connects are the cross connects located in
an
equipment room.
MAN
metropolitan area
network
MCU
mobile control
unit
Media
See transmission
medium; yielded media; unguided media.
Message
Telecommunications Service (MTS)
MTS is a
non-private-line intrastate and interstate long-distance that uses in whole or
in part the public switched telephone network (PSTN).
MFJ
Modification of
Final Judgment
MFOTS
Military
Fiber-Optic Transmission System
MF
multiple frequency
MHS
message handling
system
MIB
management
information base
MIC
Material
Identification Code
Microwave
In
telecommunications, microwaves are frequencies above 1 GHz.
MIPS
million
instructions per second
Modems (MOdulator/DEModulators)
Modems are devices
that transform digital signals generated by data terminal equipments (DTEs) to analog signal formats, suitable for
transmission through the extensive, world-wide connectivity of public and
private, switched (dial up) and non-switched telephone voice networks.
Modification Of Final
Judgment (MFJ)
MFJ is a ruling
issued by U.S. District Court Judge Harold Greene which concluded the U.
S. Justice Department's antitrust suit against AT&T by modification of an
earlier (1956) consent decree's final judgment.
Modulation
Modulation is the
process of varying certain parameters of a carrier signal i.e., a signal
suitable for modulation by an information signal by means of another signal (the
modulating or information bearing signal).
MPEG
Moving Pictures
Experts Group
MSS
metropolitan
switching system
MTSO
mobile telephone
switching office
MTS
message
telecommunications service
Multiline Telephone
A multiline telephone is a telephone that incorporates visual
displays and switches (keys) that permit the station user to access more than one central office or other line
and to perform other desired functions. Typical functions include answering or originating a call on
a selected line, putting a call on hold, operating an intercom feature, a buzzer, etc. Displays
can indicate busy, ringing and message waiting status.
Multimode Optical
Fiber(S)
Multimode fibers,
with much wider cores than single mode fibers, allow light to enter at various angles, and reflect (bounce off of) core-clad boundaries as electromagnetic
(light) wave propagates from transmitter to receiver. From a technical performance trade-off
point of view, single mode fiber exhibits bandwidths of up to 100,000 MHz (MHz = 1,000,000
hertz or cycles per second = one megahertz) while multimode band width is in the range of 1,000
to 2,000 MHz
(1,000 MHz = one billion hertz = one gigahertz = 1 GHz). See optical fiber(s);
single modefiber(s).
Multiplexing
Multiplexing is a
technique that enables a number of communications channels to be combined into a single broadband signal and transmitted over a single circuit. At the receiving terminal, demultiplexing of the broadband signal separates and recovers the original channels. Multiplexing makes
more efficient use of transmission capacity to achieve a low per channel cost.
Two basic multiplexing methods used in telecommunications systems, are frequency
division multiplexing (FDM) and time division multiplexing (TDM).
NBEC
non-Bell exchange
carrier
NCP
network control
point
NCTE
network channel
terminating equipment
Network Control Point
(NCP)
In virtual private
networks, the Network Contol Point is a centralized
database that stores a subscriber's unique VPN definition. Highly sophisticated, this database screens
every call and applies call processing control in accordance with customer-defined
requirements.
Network Operating
System (NOS)
NOS is software
that controls the execution of network programs and modules. Structurally, networking software comprises multiple modules, most residing in network
servers, but some must be installed in each terminal/station that can access network resources.
Peer-to-peer NOSs permit any terminal/station to act as a resource server or a client, and can be
based on Microsoft's Disk operating system (MS DOS) designed for IBM and compatible PCs.
Since MS DOS is not designed to run multiple programs and respond to many
simultaneous users, most NOSs designed for large
networks with dedicated servers/superservers, have a
multitasking and multi-user architecture. Advanced NOS products support network
management, diagnostics, and administration, as well as, primary server, client, de vice and external
network driver functions.
Network Services
Network Services
are specified sets of information transfer capabilities furnished to
users between telecommunications network points of termination. Network services
categories include access and transport, public and private, and switched and non-switched.
NIC
network interface
card
NIST
National Institute
of Standards and Technology
NI
network interface
NNX
Before the use of
"1" in direct distance dialing, NNX indicated the first three numbers
of a North American local telephone number. These numbers are now designated as
NXX, allowing local central offices to have numbers that look like area codes.
NOC
network operations
center
NOS
network operating
system
NPA
numbering plan
area
NSEP
National Security
& Emergency Preparedness
NTSC
National Television
System Committee
NT
network
termination
OA&M
operation
administration & maintenance
OCC
other common
carriers
Ohms Restriction
Ohms Restriction
is the same as Ohms resistance. Ohms are measures of resistance. A
resistance of one Ohm allows one Ampere of current to pass at the electric potential of
one Volt.
Open Systems
Interconnection (OSI) standards
OSI standards are
standards for the exchange of information among systems that are
"open" to one another by virtue of incorporating ISO standards. The OSI reference model
segments communications functions into seven layers. Each layer relies on the next lower
layer to provide more primitive functions and, in turn, provides services to support the next
higher layer.
Operating Telephone
Company
An operating
telephone company is any Bell-operating company or independent telephone company (termed exchange carrier in the MFJ) operating in
North America
.
Optical Fiber(s)
Optical fibers are
light guides for electromagnetic waves in the infrared and visible light
spectrum composed of concentric cylinders made of dielectric materials
with different indices of refraction (i.e., velocity of propagation
normalized to the velocity of light in free space). At the center is a core comprising the glass or plastic strand or
fiber in which a light wave travels. A low index of refraction clad
surrounds the core and is itself enclosed in a light-absorbing jacket that
prevents interference among multi-fiber cables. Multi-fiber cable can be
purchased with between 2 and 136 fibers.
OPX
off-premises
extension
OSC
operating system
control
OSI
open systems
interconnection
OSS
operations support
systems or operational support system
Out Of Band Signaling
Out of band
signaling uses the same channel path as the voice traffic but signaling is in a frequency
band outside that used for the voice traffic. In digital systems, out-of-band
signaling may take the appearance of an allocated bit position or a dedicated channel or
time slot.
P-MAC
packet media
access controller
PAD
packet assembler-disassembler
PCB
printed circuit
board
PDS
premises
distribution system
Personal Communications
Personal
communications provides at least one human operator with direct terminal access
and real time or near real time interactive communications with a remote human
opera tor or an information system resource. Personal communications can refer to a broad range
of services, systems and equipment, e.g., facsimile machines, landline telephones, cellular tele phone systems and emerging personal communication system (PCS) adjuncts, and a
variety of radio systems including pagers, hand-held remote data entry terminals, and autonomous
citizen-band-like radio systems.
PHY
physical-layer
protocol
PMD
physical-layer
media-dependent
Point-of-presence (POP)
A POP is a
physical location within a LATA that an IXC establishes for the purpose of
gaining access to BOC/LEC networks within the LATA using LEC provided access services.
An IXC may have more than one POP within a LATA and the POP may support public and
private, switched and non switched services.
POP
point-of-presence
POT
point of
termination
PPSN
public packet
switched network
Premises Distribution
System (PDS)
PDS is the
transmission network inside a building or among a group of buildings, for
example an office park or a campus. PDS is used in this book as a generic term although
AT&T used it to describe a specific product offering. The PDS connects desktop and other
station equipment with common host equipment, (e.g., switches, computers and building automation
systems), and to external telecommunications networks.
Private Branch Exchange
(PBX)
A PBX is a
premises switching system, serving a commercial or government organization,
and usually located on that organization's premises. PBXs provide
telecommunications services on the premises or campus, (e.g., internal calling and other services), and access to
public and private telecommunications network services.
Private Network
A private network
is a network made up of circuits and, sometimes, switching equipment, for
the exclusive use of one organization.
PRI
primary rate
interface
Protocols
Protocols are
strict procedures for the initiation, maintenance and termination of data communications. Protocols define the syntax (arrangements, formats and patterns
of bits and bytes) and the semantics (system control, information context or meaning of
patterns of bits or bytes) of exchanged data, as well as numerous other characteristics (data
rates, timing, etc.).
PSN
packet switched network
PSPDN
packet switched
public data network
PSTN
public switched
telecommunications network
PTT
postal, telephone,
and telegraph
Public Switched
Telephone Network (PSTN)
A Public Switched
Telephone Network (PSTN) denotes those portions of the LEC and IXC networks that provide public switched telephone network services.
PUC
public utility
commission
Pulse Code Modulation
(PCM)
Pulse Code
Modulation (PCM) is a modulation scheme involving conversion of a signal
from
analog to digital form by means of coding. See also modulation.
PVC
permanent virtual
circuit
Quantizing Noise
In any analog to digital conversion
process, e.g., PCM, quantizing noise is the difference between the
converted binary value and the actual analog signal's amplitude.
RAO
Revenue Accounting
Office
RBHC
Regional Bell
Holding Company
RBOC
Regional
Bell
Operating company
RBS
robbed bit
signaling
Regional Bell Holding
Company (RBHC)
RBHC is one of 7
regional companies created by the AT&T divestiture to assume ownership
of the
Bell
operating companies. They are
Ameritech, Bell Atlantic, Bell South, NYNEX, Pacific Telesis,
Southwestern
Bell
and
US West.
Repeater
In digital
transmission, a repeater is equipment that receives a pulse train, amplifies
it, retimes it, and then reconstructs the signal for retransmission. In
IEEE 802 local area network (LAN) standards, a repeater is essentially two transceivers joined back to back and
attached to two adjacent LAN segments. See transceiver.
RFC
request for
comment
RFE
Request for Engineering
RFI
radio frequency
interference
RFP
request for
proposal
RF
radio frequency
Routers
In IEEE 802 local
area network (LAN) standards, routers are devices that connect autonomous networks of like architecture at the network layer (layer 3). Unlike a bridge
which operates transparently to communicating end-terminals at the logical link layer (layer
2), a router reacts only to packets addressed to it by either a terminal or another router. Routers
perform packet (as opposed to frame) routing and forwarding functions;
they can select one of many potential paths based on transit delay,
network congestion or other criteria. How routers perform their functions is
largely determined by the protocols implemented in the networks they
interconnect.
RSU
remote switching
unit
SAFENET
survivable
adaptable fiber-optic embedded network
Satellite
Communications
Satellite
communications entails microwave radio, line-of-sight propagation from a
transmitting earth terminal (i.e., usually ground-based but potentially ship or airborne)
through the atmosphere and outer space media to a satellite, and back to
earthbound receiving terminals. In essence, satellites are equivalent to
orbiting microwave repeaters.
Scenario
In SWAT, a
scenario is an iteration of an RFW project. A scenario holds the design detail
work units that are associated with the project. By creating multiple scenarios, you
can compare pricing and scheduling options. A scenario has three different statuses. A
Working status indicates that the scenario is under reivew. A Posted
status indicates that a scenario has been identified as the official design. A Final Posted status indicates that a
scenario is the "as-built" version of the project.
SDH
synchronous
digital hierarchy
SDN
software defined
network
SECAB
Small Exchange
Carrier Access Billing
Server
In a network, a
server is equipment that makes available file, database, printing,
facsimile, communications or other services to client terminals/stations with access to
the network. A gateway is a server that permits client terminal/station access to external
communications networks and/or information systems.
Service Management
System (SMS)
In virtual private
networks, SMS is a facility used to build and maintain a VPN database
allowing customers to program specific functions for unique business applications. The
SMS contains complete specifications of customer defined private network specifications
including location data, numbering plan, features, screening actions, authorization codes, calling
privileges, etc. This information is downloaded (transmitted) to network control points (NCPs) which implement
its instructions on a customer-by-customer basis.
Service Order (SO)
A service order is
a record that describes a customer request to establish, change, or terminate
a service. The service order contains all information required to meet a
