American National Standards Institute (ANSI)

An organization that certifies standards developed by a wide variety of industry groups. ANSI does not create standards, but rather consolidates those which have been created by other organizations.


Analog Transmission

The traditional telephone technology (for voice transmission) in which sound waves (or other data) are converted into electrical impulses of varying strength or amplitude.



High-capacity network infrastructure; the part that carries the heaviest traffic. The backbone is also that part of the network that joins LANs together - either inside a building or across a country. LANs are connected to the backbone by bridges and/or routers; the backbone serves as a communications highway for LAN-to-LAN traffic.



The common measure of transmission capacity. For analog transmission, it is measured in cycles per second; for digital transmission, it is measured in bits per second.


Basic Rate ISDN (BRI)

A 2-wire line-side local switching system port that uses the 2B1Q line code at a 160 kilobit per second rate to transport overhead and up to two B channels and one D channel.


Billing Telephone Number (BTN)

The ten-digit number, including the area code, to which charges for a given telephone service are billed.


Bipolar Eight Zero Substitution (B8ZS)

A DS1 line code that performs zero code suppression by replacing an all-zeros byte with a special pattern of ones and zeros that contains two consecutive bipolar violations.


Bipolar Violation (BPV)

The presence of two consecutive "one" bits of the same polarity on a T1 facility.



The smallest unit of information in the binary system of notation.


Bit Rate

The speed at which digital signals are transmitted, usually expressed in bits per second (bps).



A device that connects and passes data packets between two network segments.


Bridge Router

A device that can provide the functions of a bridge, router or both concurrently. A bridge/router can route one or more protocols, such as TCP/IP and/or XNS, and bridge all other traffic.



A data-transmission scheme in which multiple signals share the bandwidth of a medium such as fiber-optic cable. This allows the transmission of voice, data and video signals over a single medium; for example, cable television uses broadband to deliver dozens of channel signals over a single cable.



A two-way communication path.


Coaxial Cable

A transmission line in which one conductor is a wire at the center of the cable; the other conductor surrounds the center wire with a layer of insulating material between them. Coaxial cable can transmit greater bandwidth than twisted pair (TP) wires.


Customer Premise Equipment (CPE)

Telephone terminating equipment, such as handsets, PBXs, and modems located on the customer's premises and connected to the phone service provider network.


Decibel (dB)

The logarithmic unit of signal power ratio most commonly used in telephony. It is used to express the relationship between two signal powers, usually between two acoustic, electric, or optical signals.


Digital or Digitized

Any type of information that can be output, transmitted and interpreted as individual bits of binary information (the use of the numbers 0 and 1), using electrical or electronmagnetic signals that can be modulated to convey their specific content.


Digital Transmission

A mode of transmission in which all information is transmitted in digital form as a serial stream of pulses. Sound waves and other information are converted into binary computer code (a series of 0s and 1s) and transmitted to the end point. At the end point, binary code is converted back into the original format. Digital transmission provides sharper, clearer, faster transmission than analog transmission.


E-911 Service

An emergency call service that routes 911 calls to a Public Safety Answering Point.


End User

Any customer of a telecommunications service that is not a carrier, except for the following exceptions:

   1.A carrier other than a telephone service provider is considered to be an "end user," when the carrier uses a telecommunications              service for administrative purposes.

   2.A person or entity that offers telecommunications services exclusively as a Reseller is considered to be an "end user" if all resale              transmissions offered by the reseller originate on the premises of the reseller.


Enterprise Network

A geographically dispersed network under the auspices of one organization.


Entrance Facility

Point of interconnection between the local exchange carrier's (LEC) Rate Demarcation Point and the external carrier's Point of Presence (POP).



A 100-Mbps technology based on the 10BASE-T Ethernet CSMA/CD network access method to accommodate the operation of local area networks (LANs).



A unit generally smaller than a LATA, established by the local exchange carrier (LEC) for the administration of communications service in a specified area (usually a city, town, or village and its environs). An exchange consists of one or more central offices together with the associated facilities used to provide communications services within that area. One or more designated exchanges comprise a given LATA.



A 100-Mbps technology based on the 10BASE-T Ethernet CSMA/CD network access method to accommodate the operation of local area networks (LANs).


Fiber Optics

Communications technology that uses thin filaments of glass or other transparent materials. Fiber optic technology offers extremely high transmission speeds, allowing for data-intensive services such as video on demand.


Graphical User Interface (GUI)

Computer interface that lets users access programs and enter data by using a mouse; considered to be user-friendly.  


Integrated Services Digital Network (ISDN) A widely available high bandwidth switched network service providing end-to-end digital connectivity over standard phone lines for simultaneous transmission of voice and data. There are two levels of service:

    1.Basic Rate Interface-ISDN (BRI-ISDN)--provides for digital transmission of two 64 kbps bearer channels and one 16 kbps data and             signaling channel (2B+D).  

    2.Primary Rate Interface-ISDN (PRI-ISDN)--provides for digital transmission of twenty three (23) 64 kbps bearer channels and one (1)         64kbps data and signaling channel (23 B+D).



Unwanted electrical signals or noise causing degradation of reception on a communications circuit.


Internet Access

The connection which allows you to get on the Internet through an Internet Service Provider (ISP), of your choice. The type of connection you choose is based on a number of different factors, including cost and the communications system you have.


Internet Address

Also called an IP (Internet Protocol) address; a 32-bit address assigned to hosts using TCP/IP .The address is written as four octets separated with periods (dotted decimal format) that are made up of a network section, an optional subnet section and a host section.


Internet Protocol

Part of the TCP/IP family of protocols that tracks the outgoing address of nodes, routes outgoing messages and recognizes incoming messages.


Internet Service Provider

A vendor that provides direct access to the Internet, and services such as email. The user accesses the ISP by dialing up through a personal computer and modem, or through a dedicated line. Also known as an Internet Access Provider (IAP).


IP Address

Internet Protocol address; a 32-bit address assigned to hosts using TCP/IP. The address is written as four octets separated with periods (dotted decimal format) that are made up of a network section, an optional subnet section and a host section. Also known as an Internet Address.


IP Port

A service element in the Internet Protocol Virtual Private Network (IP-VPN) tariff: a physical port on a router.


Kbps or Kbs

See Kilobits per second.


Kilobits per second (Kbps or Kbs)

A measurement for data transmission. One kilobit per second is one thousand bits per second.



See Local Area Network.


Local Area Network (LAN)

A short-distance data communications network. LANs are typically within a building or campus, and to link together computers and peripherals under a standard protocol. The network provides high-bandwidth communications over coaxial cable, twisted-pair, fiber, or microwave media. LANs are usually owned by the user.


Local Exchange

A local exchange is the local central office of a LEC Lines from homes and businesses terminate at a local exchange. Local exchanges connect to other local exchanges within a LATA or to Interexchange Carriers also known as long-distance carriers.


Main Distribution Frame (MDF)

The primary point at which outside plant facilities terminate within a wire center for interconnection to other telecommunications facilities within the wire center. Also known as Central Office Distribution Frame.


Megabits (Mb)

A measure, representing 1,000,000 bits, generally used to express the speed per second of telecommunications services and equipment. See Kilobit A bit is the smallest unit used to express digital information.


Megabits per second (Mbps)

A measurement of data transmission. One megabit per second equals one million bits per second.



A measure, representing 1,000,000 bytes generally used to express the storage capacity of digital A components. A byte represents a single character, or group of eight bits.


Packet Switched

A form of data transmission in which data is broken into small packets that are transmitted independently and reassembled at the destination. This is in contrast with circuit-switching, traditionally used for voice telephony, in which the transmission occurs over a dedicated circuit.


Plain Old Telephone Service (POTS)

The basic single line switched access service offered by local exchange carriers to residential and business end users, using loop-start signaling.


Point of Presence (POP)

The physical place within a LATA where a long distance carrier or a cellular provider interfaces with the network of the local exchange carrier.


Ported Out

A telephone number is considered to be ported out when a number assigned to service provider A is moved from service provider A's switch to service provider B's switch, using local routing number (LRN) technology.


Primary Rate ISDN (PRI)

PRI is a 4-wire 1.544 megabits per second (DS1) local switching system port that uses the B8ZS line code and the ESF framing format. PRI is available in a twenty-three B channel plus one D channel (23B + D) configuration or a twenty-four B channel (24B) configuration.


Private Branch Exchange (PBX)

A private telephone switching system commonly located on the end user premises with an attendant console. The PBX is connected to a common group of lines from one or more central offices to provide service to a number of individual phones.


Public Switched Telephone Network (PSTN)

1.The worldwide voice telephone network.

2. Any common carrier network that provides circuit switching among public users.



A networked computer that stores information and makes it available upon request to client programs that may be located on other computers. "Client-server" computing is the basis of virtually all local area networks and the World Wide Web.


T-1 Circuit

A digital circuit that uses the DS-1 signaling format to transmit information over the telephone network at 1.544 megabits per second. Can carry up to 24 uncompressed voice channels.



Transmission Control Protocol/Internet Protocol (TCP/IP)

A widely used network protocol that supports communication across interconnected networks; and between computers with diverse hardware architectures and various operating systems.



A measure of the overall efficiency, quality and performance of a communications link and its software/protocols.



A communications path connecting two switching systems in a network, used to establish an end-to-end connection.