- See Asymmetric Digital Subscriber Line.
- A specific procedure used to modify a signal. For example, the
key to a digital compression system is the algorithm that eliminates
National Standards Institute (ANSI) - An official body
within the United States delegated with the responsibility of defining
Standard Code for Information Interchange (ASCII) - Assigns
specific letters, numbers, and control codes to the 256 different
combinations of 0s and 1s in a byte.
wire gauge (AWG) - A measurement of wire diameter - the
lower the AWG number, the larger the wire diameter. Copper phone
wiring usually comes in 24 or 26 AWG.
- A continuously varying signal or wave. As with all waves, analog
waves are susceptible to interference which can change the character
of the wave.
- See American National Standards Institute
- See American Standard Code for Information Interchange.
digital subscriber line (ADSL) - A group of DSL technologies
that reserve more bandwidth in one direction than the other, which
is advantageous for users that do not need equal bandwidth in both
directions. See DSL.
- Occurring at different times. For example, electronic mail is asynchronous
communication because it does not require the sender and receiver
to be connected at the same time.
transfer mode (ATM) - A method of data transportation whereby
fixed length packets are sent over a switched network. The ability
to ensure reliable delivery of packets at a high rate makes it suitable
for carrying voice, video, and data.
on demand - A type of media that delivers sound programs
in their entirety whenever a listener requests the delivery.
- See American Wire Gauge
- The part of a communications network that handles the major traffic
using the highest-speed, and often longest, paths in the network.
- A measure of capacity of communications media. Greater bandwidth
allows communication of more information in a given period of time.
Bandwidth is generally described either in terms of analog signals
in units of Hertz (Hz), which describes the maximum number of cycles
per second, or in terms of digital signals in units of bits per
rate ISDN (BRI-ISDN) - The basic rate ISDN interface provides
two 64 Kb/s channels (called B channels) to carry voice or data
and one 16 Kb/s signaling channel (the D channel) for call information.
- A single unit of data, either a one or a zero, used in digital
data communications. When discussing digital data a small "b"
refers to bits, and a capital "B" refers to bytes.
- An adjective used to describe large-capacity networks that are
able to carry several services at the same time, such as data, voice,
integrated services digital network (BISDN) - A second-generation
ISDN technology that uses fiber optics for a network that can transmit
data at speeds of 155 megabits per second and higher.
- See broadband integrated services digital network.
- A compilation of bits, seven bits in accordance with ASCII standards
and eight bits in accordance with EBCDIC standards.
- See Carrierless Amplitude Phase
- an electromagnetic wave or alternating current which is modulated
to carry signals in radio, telephonic, or telegraphic transmission.
amplitude phase (CAP) - A type of quadrature amplitude
modulation, used for some types of DSL, that stores pieces of a
modulated message signal in memory and then reassembles the parts
in the modulated wave.
office (CO) - A telephone company facility that handles
the switching of telephone calls on the public switched telephone
network (PSTN) for a small regional area.
processing unit (CPU) - The "brains" of a computer,
which uses a stored program to manipulate information.
network - A type of network in which a continuous link
is established between a source and a receiver. Circuit switching
is used for voice and video to ensure that individual parts of a
signal are received in the correct order by the destination site.
- See central office
carrier - A business, including telephone and railroads,
which is required by law to provide service to any paying customer
on a first-come, first-serve basis.
local exchange carrier (CLEC) - An American term for a
telephone company that was created after the Telecommunications
Act of 1996 made it legal for companies to compete with the ILECs.
Contrast with ILEC.
- See competitive local exchange carrier.
- The process of reducing the amount of information necessary to
transmit a specific audio, video, or data signal. core network -
The combination of telephone switching offices and transmission
plant connecting switching offices together. In the U.S. local exchange
network, core networks are linked by several competing Interexchange
networks; in the rest of the world the core network extends to national
- See customer premises equipment.
- See central processing unit.
- Interference from an adjacent channel.
premises equipment (CPE) - Any piece of equipment in a
communication system that resides within the home or office. Examples
include modems, television set-top boxes, telephones and televisions.
- See direct broadcast satellite.
connection - A communication link that operates constantly.
connection - A data communication link that is established
when the communication equipment dials a phone number and negotiates
a connection with the equipment on the other end of the link.
signal - A signal that takes on only two values, off or
on, typically represented by "0" or "1." Digital
signals require less power but (typically) more bandwidth than analog,
and copies of digital signals can be made exactly like the original.
subscriber line (DSL) - A data communications technology
that transmits information over the copper wires that make up the
local loop of the public switched telephone network (See local loop).)
It bypasses the circuit-switched lines that make up that network
and yields much faster data transmission rates than analog modem
subscriber line access multiplexor (DSLAM) - A device found
in telephone company central offices that takes a number of DSL
subscriber lines and concentrates these onto a single ATM line.
broadcast satellite (DBS) - A broadcast technology that
uses satellites orbiting the Earth to broadcast television or data
signals to an 18" dish antenna.
multi-tone modulation (DMT) - A method of transmitting
data on copper phone wires that divides the available frequency
range into 256 sub-channels or tones, and which is used for some
types of DSL.
wavelet multitone (DWMT) - A variation of DMT modulation
that improves performance by using wavelets rather than tones to
provide additional isolation of sub-channels.
- See discrete multi-tone modulation.
- See domain name system. domain name system (DNS) - The protocol
used for assigning text addresses (such as www.2wire.com) for specific
computers and computer accounts on the Internet.
- See digital subscriber line access multiplexor.
- See discrete wavelet multitone.
- A dedicated digital communication link provided by a European
telephone company that offers 2.048 megabits per second of bandwidth,
commonly used for carrying traffic to and from private business
networks and Internet service providers
cancellation - The elimination of reflected signals ("echoes")
in a two-way transmission created by some types of telephone equipment,
used in data transmission to improve the bandwidth of the line.
- See frequency division multiplexing. fiber optics. Thin strands
of ultrapure glass or plastic that can be used to carry light waves
from one location to another.
(FTTCab) - network architecture where an optical fiber
connects the telephone switch to a street-side cabinet where the
signal is converted to feed the subscriber over a twisted copper
(FTTC) - The deployment of fiber optic cable from a central
office to a platform serving numerous homes. The home is linked
to this platform with coaxial cable or twisted pair (copper wire).
Each fiber carries signals for more than one residence, lowering
the cost of installing the network versus fiber to the home.
(FTTH) - The deployment of fiber optic cable from a central
office to an individual home. This is the most expensive broadband
network design, with every home needing a separate fiber optic cable
to link it with the central office.
relay - A high-speed packet switching protocol used in
wide area networks (WANs), often to connect local area networks
(LANs) to each other, with a maximum bandwidth of 44.725 megabits
- The number of oscillations in an alternating current that occur
within one second, measured in Hertz (Hz).
division multiplexing (FDM) - The transmission of multiple
signals simultaneously over a single transmission path by dividing
the available bandwidth into multiple channels that each cover a
different range of frequencies.
- See fiber-to-the-curb.
- See fiber-to-the-home.
video - The projection of 20 or more frames (or still images)
per second to give the eye the perception of movement. Broadcast
video in the United States uses 30 frames per second, and most film
technologies use 24 frames per second.
- A kind of asymmetric DSL technology, based on DMT modulation,
that offers up to 8 megabits per second downstream bandwidth, 1.544
Megabits per second upstream bandwidth. "G.dmt" is actually
a nickname for the standard officially known as ITU-T Recommendation
G.992.1. (See International Telecommunications Union.)
[pronounced "G-dot-light"] - A kind of asymmetric
DSL technology, based on DMT modulation, that offers up to 1.5 megabits
per second downstream bandwidth, 384 Kilobits per second upstream,
does not usually require a splitter and is easier to install than
other types of DSL. "G.lite" is a nickname for the standard
officially known as G.992.2. (See International Telecommunications
- See G.dmt.
- See G.lite.
switched telephone network (GSTN) - See public switched
- 1,000,000,000 bytes, or 1,000 megabytes (see Byte).
user interface (GUI) - A computer operating system that
is based upon icons and visual relationships rather than text. Windows
and the Macintosh computer use GUIs because they are more user friendly.
- See general switched telephone network.
- See graphical user interface.
- See high bit rate digital subscriber line.
- See frequency.
fiber/coax (HFC) - A type of network that includes coaxial
cables to distribute signals to a group of individual locations
(typically 500 or more), and a fiber optic backbone to connect these
bit rate digital subscriber line (HDSL) - A symmetric DSL
technology that provides a maximum bandwidth of 1.5 megabits per
second in each direction over two phone lines, or 2 Megabits per
second over three phone lines.
bit rate digital subscriber line II (HDSL II) - A descendant
of HDSL which offers the same performance over a single phone line.
television (HDTV) - Any television system that provides
a significant improvement in picture quality over existing television
systems. Most HDTV systems offer more than 1,000 scan lines, in
a wider aspect ratio, with superior color and sound fidelity.
- See hypertext markup language.
- See hypertext transfer protocol.
- Documents or other information with embedded links that enable
a reader to access tangential information at specific points in
markup language (HTML) - The computer language used to
create hypertext documents, allowing connections from one document
or Internet page to numerous others. HTML is the primary language
used to create pages on the World Wide Web.
transfer protocol (HTTP) - The first part of an address
(URL) of a site on the Internet, signifying a document written in
Hypertext Markup Language (HTML).
- See frequency.
- See ISDN digital subscriber line.
- See Institute of Electrical and Electronics Engineers.
- See incumbent local exchange carrier.
local exchange carrier (ILEC) - A large telephone company
that has been providing local telephone service in the United States
since the divestiture of the AT&T telephone monopoly in 1982.
of Electrical and Electronics Engineers (IEEE) - A membership
organization comprised of engineers, scientists and students that
sets standards for computers and communications.
services digital network (ISDN) - A circuit-switched communication
network, closely associated with the public switched telephone network,
that allows dial-up digital communication at speeds up to 128 kilobits
carrier (IXC) - A long-distance telephone carrier.
Organization of Standardization (ISO) - Develops, coordinates,
and promulgates international standards that facilitate world trade.
Telecommunication Union (ITU) - A United Nations organization
that coordinates use of the electromagnetic spectrum and creation
of technical standards for telecommunication and radio communication
Telecommunication Union/Telecommunication Standardization Sector
(ITU-T) - The branch of the ITU that is responsible for
Engineering Task Force (IETF) - The standards organization
that standardizes most Internet communication protocols, including
Internet protocol (IP) and hypertext transfer protocol (HTTP).
- See Internet Engineering Task Force.
protocol (IP) - The standard signaling method used for
all communication over the Internet
service provider (ISP) - An organization offering and providing
Internet access to the public using computer servers connected directly
to the Internet.
- A network serving a single organization or site that is modeled
after the Internet, allowing users access to almost any information
available on the network. Unlike the Internet, intranets are typically
limited to one organization or one site, with little or no access
to outside users.
- See Internet protocol
- See integrated services digital network.
digital subscriber line (IDSL) - A type of DSL that uses
ISDN transmission technology to deliver data at 128kbps into an
IDSL "modem bank" connected to a router.
- See International Organization of Standardization.
- See Internet service provider.
- See International Telecommunication Union.
- See International Telecommunication Union/Telecommunication Standardization
- See Inter-exchange carrier.
Photographic Experts Group (JPEG) - A committee formed
by the International Organization of Standardization to set standards
for digital compression of still images. Also refers to the digital
compression standard for still images created by this group.
- See Joint Photographic Experts Group.
- One thousand bits (see bit).
- One thousand bytes (see byte).
- From the acronym for "Light Amplification by Stimulated Emission
of Radiation." A laser usually consists of a light-amplifying
medium placed between two mirrors. Light not perfectly aligned with
the mirrors escapes out the sides, but light perfectly aligned will
be amplified. One mirror is made partially transparent. The result
is an amplified beam of light that emerges through the partially
mile - See local loop.
access transport area (LATA) - The geographical areas defining
local telephone service. Any call within a LATA is handled by the
local telephone company, but calls between LATAs must be handled
by long-distance companies, even if the same local telephone company
provides service in both LATAs.
- See local access transport area.
area network (LAN) - A network connecting a number of computers
to each other or to a central server so that the computers can share
programs and files.
- See local area network.
exchange carrier (LEC) - A local telephone company. LECs
provide telephone service for phone calls originating and terminating
within a single LATA.
loop - The copper lines between a customer's premises and
a telephone company's central office (See central office).
- Megabits per second.
- One million bits.
- 1,000,000 bytes, or 1,000 kilobytes (see Byte).
of instructions per second (MIPS) - This is a common measure
of the speed of a computer processor.
(MOdulator-DEModulator) - A device that converts digital
data into analog signals and vice-versa for transmission over a
Pictures Experts Group (MPEG) - A committee formed by the
ISO to set standards for digital compression of full-motion video.
Also stands for the digital compression standard created by this
- An international standard for the digital compression of VHS-quality,
- An international standard for the digital compression of broadcast-quality,
- An international standard for the digital compression of broadcast-quality,
- The transmission of information over the Internet to two or more
users at the same time.
- Transmitting multiple signals over a single communications line
or computer channel. The two common multiplexing techniques are
frequency division multiplexing, which separates signals by modulating
the data onto different carrier frequencies, and time division multiplexing,
which separates signals by interleaving bits one after the other.
- See network access provider.
- A designation of bandwidth less than 56 kilobits per second.
ISDN - same as ISDN.
access provider (NAP) - Another name for a provider of
networked telephone and associated services, usually in the U.S.
service provider (NSP) - A high-level Internet provider
that offers high-speed backbone services.
termination equipment (NTE) - The equipment at the ends
of the communication path.
- See narrowband ISDN.
- See network service provider.
- See network termination equipment.
- See optical carrier 3.
- See optical network unit.
carrier 3 (OC-3) - An fiber optic line carrying 155 megabits
per second; a U.S. designation generally recognized throughout the
telecommunications community worldwide.
network unit (ONU) - A form of access node that converts
optical signals transmitted via fiber to electrical signals that
can be transmitted via coaxial cable or twisted pair copper wiring
to individual subscribers. (See hybrid fiber/coax.)
network - A network that allows a message to be broken
into small "packets" of data that are sent separately
by a source to the destination. The packets may travel different
paths and arrive at different times, with the destination sites
reassembling them into the original message. Packet switching is
used in most computer networks because it allows a very large amount
of information to be transmitted through a limited bandwidth.
optical network (PON) - a fiber-based transmission network
containing no active electronics.
- An external device that increases the capabilities of a communication
old telephone service (POTS) - An acronym identifying the
traditional function of a telephone network to allow voice communication
between two people across a distance. In most contexts, POTS is
synonymous with the public switched telephone network (PSTN).
of presence (POP) - The physical point of connection between
a data network and a telephone network.
- See passive optical network.
- See point of presence.
Telegraph and Telephone (PTT) - The generic European name
usually used to refer to state-owned telephone companies.
- See plain old telephone service.
splitter - A device that uses filters to separate voice
from data signals when they are to be carried on the same phone
line, required for several types of DSL service.
- See primary-rate ISDN.
ISDN (PRI-ISDN) - The primary rate ISDN interface provides
23 64 Kb/s channels (called B channels) to carry voice or data and
one 16 Kb/s signaling channel (the D channel) for call information.
- See Postal, Telegraph and Telephone. public switched telephone
network (PSTN) - The worldwide communications network that carries
phone calls and data.
frequency (RF) - Electromagnetic carrier waves upon which
audio, video, or data signals can be superimposed for transmission.
- See rate-adaptive asymmetric digital subscriber line.
digital subscriber line (RADSL) - A variation of DSL that
uses carrierless amplitude phase modulation, divides the available
frequencies into discrete sub-channels and also maximizes performance
by adjusting the transmission to the quality of the phone line while
- See Regional Bell Operating Company.
Bell Operating Company (RBOC) - One of the seven local
telephone companies formed upon the divestiture of AT&T in 1984.
The seven are: NYNEX, Bell Atlantic, BellSouth, Southwestern Bell,
U S WEST, Ameritech, and Pacific Telesis.
- See radio frequency.
- The central switching device in a packet-switched computer network
that directs and controls the flow of data through the network.
- See small computer system interface.
computer system interface (SCSI) [pronounced "scuzzy"]
- A type of interface between computers and peripherals that allows
faster communication than most other interface standards, often
used to connect PCs to external disk drives.
sdsl - Symmetric
Digital Subscriber Line - This technology provides the same
bandwidth in both directions, upstream and downstream. That means
whether you're uploading or downloading information, you have the
same high-quality performance. SDSL provides transmission speeds
within a T1/E1 range, of up to 1.5 Mbps at a maximum range of 12,000
- 18,000 feet from a central office, over a single-pair copper wire.
This option is ideal for small and medium sized businesses that
have an equal need to download and upload data over the Internet.
- The American National Standards Institute (ANSI) standard for
asymmetric digital subscriber line using discrete multitone modulation,
which the G.dmt standard is based on.
- Also known as DS1 and T1, a T-1 is dedicated digital communication link provided by a telephone
company that offers 1.544 megabits per second of bandwidth, commonly
used for carrying traffic to and from private business networks
and Internet service providers.
- Also known as DS3 and T3, a T-3 is a dedicated digital communication link provided by a telephone
company that offers 44.75 megabits per second of bandwidth, commonly
used for carrying traffic to and from private business networks
and Internet service providers.
- See transmission control protocol/Internet protocol.
- The practice of using telecommunication technologies to facilitate
work at a site away from the traditional office location and environment.
teleconference - Interactive, electronic communication among three
or more people at two or more sites. Includes audio-only, audio
and graphics, and video-conferencing.
- 1,000,000,000,000 bytes, or 1,000 gigabytes (see Byte).
division multiplexing (TDM) - A digital data transmission
method that takes signals from multiple sources, divides them into
pieces which are then placed periodically into time slots, transmits
them down a single path and reassembles the time slots back into
multiple signals on the remote end of the transmission.
control protocol/Internet protocol (TCP/IP) - A method
of packet-switched data transmission used on the Internet. The protocol
specifies the manner in which a signal is divided into parts, as
well as the manner in which "address" information is added
to each packet to ensure that it reaches its destination and can
be reassembled into the original message.
pair - The set of two copper wires used to connect a telephone
customer with a switching office, loosely wrapped around each other
to minimize interference from other twisted pairs in the same bundle.
Synonymous with 2-wire line.
- See Universal ADSL Working Group.
Resource Locator (URL) - A text-based address used to identify
specific resources on the Internet, such as web pages. URLs are
arranged in a hierarchical form that specifies the name of the server
on which a resource is located (such as www.2wire.com) and the name
of the file on that server (www.2wire.com/index.html).
ADSL Working Group (UAWG) - An organization composed of
leading personal computer industry, networking and telecommunications
companies with the goal of creating an interoperable, consumer-friendly
ADSL standard titled the G.992.2 standard, and commonly referred
to as the G.lite standard.
Serial Bus (USB) - A computer interface with a maximum
bandwidth of 1.5 Megabytes per second used for connecting computer
peripherals such as printers, keyboards and scanners.
service provider (USP) - A company that sells access to
phone, data, and entertainment services and networks.
- See Uniform Resource Locator.
- See Universal Serial Bus.
- See universal service provider.
bit rate (VBR) - A data transmission that can be represented
by an irregular grouping of bits or cell payloads followed by unused
bits or cell payloads.
- See very high bit rate digital subscriber line. very high bit rate
digital subscriber line (VDSL) - An asymmetric DSL that delivers
from 13 to 52 megabits per second downstream bandwidth and 1.5 to
2.3 megabits per second upstream.
on demand (VOD) - A pay-per-view television service in
which a viewer can order a program from a menu and have it delivered
instantly to the television set, typically with the ability to
pause, rewind, etc.
- Interactive, audiovisual communication among three or more people
at two or more sites.
Reality Markup Language (VRML) - A computer language that
provides a three-dimensional environment for traditional Internet
browsers, resulting in a simple form of virtual reality available
over the Internet.
- See video on demand.
- See virtual reality markup language.
- See wide area network.
area network (WAN) - A network that interconnects geographically-distributed
computers or LANs.
data protocol - A packet switching standard developed in
the mid-1970s for transmission of data over twisted pair copper
- See DSL.