10Base2

IEEE 802.3 specification, similar to Ethernet, using thin coaxial cable that runs at 10 Mbps, with a distance limit of 185 meters per segment.

10BaseT

IEEE 802.3 specification, using unshielded twisted-pair cabling and running at 10 Mbps.

100BaseT

IEEE 802.3 specification, using unshielded twisted-pair cabling and running at 100 Mbps.

800 Portability

Equal access for 800#’s

ADSL

Asymmetric Digital Subscriber Line

Aggregator

Resellers who have no switching facilities.

ANI

Automatic Number Identification – Enables a caller’s long distance company to know which phone number to bill without requiring the caller to enter an authorization code to be identified and billed.

ASCII

American Standard Code for Information Interchange. An 8-bit code for character representation (seven bits plus parity).

ATM

Asynchronous Transfer Mode. The CCITT (now ITU-T) standard for cell relay wherein information for multiple service types (such as voice, video, or data) is conveyed in small, fixed-size cells. 

Automated Attendant

A system used to answer calls without live operator intervention.

BOC

Bell Operating Company. Prior to divestiture there were 22 BOC’s operated by AT&T to provide local calling service. After divestiture, the Bell Operating Companies were regrouped and are administered by 7 interlata regional holding companies (RBOC’s) providing local and intralata calling service.

BRI

Basic Rate Interface. The ISDN interface composed of two B channels and one D channel for circuit-switched communication of voice, data, and video.

BSC

Binary synchronous communication. A character-oriented data-link protocol for half-duplex applications. Often referred to simply as bisync.

CCITT

Consultative Committee for International Telegraph and Telephone. An international organization responsible for the development of numerous communications standards. Now called the ITU-T.

CCS7: CCSS7: SS7

Common Channel Signaling System 7 – process by which network signaling routing information is communicated over high speed data channels external to the voice network.

CIR

Committed Information Rate. The rate at which a Frame Relay network agrees to transfer information under normal conditions, averaged over a minimum increment of time. CIR, measured in bits per second, is one of the key negotiated tariff metrics.

CO

Central Office. A local telephone company office to which all local loops in a given area connect and in which circuit switching of subscriber lines occurs.

CODEC

Coder-Decoder. A device that typically uses PCM to transform analog voice into a digital bit stream and vice versa.

CPE

Customer Premises Equipment. Terminating equipment, such as terminals, telephones, and modems, supplied by the telephone company, installed at customer sites, and connected to the telephone company network.

Cross Talk

Interfering energy transferred from one circuit to another.

CSU

Channel Service Unit. A digital interface device that connects end-user equipment to the local digital telephone loop.

CTI

Computer Telephony Integration. A combination of hardware and software enabling a telephone system and computer system to be linked and integrated.

D4 Framing

Framing format used on most existing 1.544-Mbps facilities.

DID

Direct Inward Dialing.

Dial-up Line

Communications circuit that is established by a switched-circuit connection using the telephone company network.

Divestiture

Term used to describe the break-up and regrouping of the Bell System as a result of the suit brought against Western Electric and AT&T by the department of Justice.

DLCI

Data Link Connection Identifier. A Frame Relay value that identifies a logical connection.

DNS

Domain Name System. A system used in the Internet for translating names of network nodes into addresses.

DS0

Digital Service level 0 - Carries 1 voice conversation.

DS1

Digital Service level 1 - Carries 24 conversations at a time.

DS3

Digital Service 3 – Carries 672 conversations at a time (28 DS1’s).

DSU

Data Service Unit. A device used in digital transmission for connecting DTE, such as a router, to DCE or to a service.

DSX-1

Cross-connection point for DS-1 signals.

DTMF

Dual Tone Multi-Frequency-Touch tone service.

E & M Signaling

Standard signaling method used over interoffice and toll trunks.

EBCDIC

Extended Binary Coded Decimal Interchange Code. An 8-bit character code developed by IBM for data representation in their large mainframe computer systems.

EIA

Electronic Industries Association. A group that specifies electrical transmission standards.

End Office

A central office to which a telephone subscriber is connected.

Equal Access

All long distance carriers must be able to be accessed by dialing "1", not a string of digits.

FDDI

Fiber Distributed Data Interface. An ANSI-defined standard specifying a 100-Mbps token-passing network using fiber-optic cable, with transmission distances of up to 2 km. Uses a dual-ring architecture to provide redundancy.

Frame Relay

A protocol used across the interface between user devices (for example, hosts and routers) and network equipment (for example, switching nodes). Frame Relay is more efficient than X.25, the protocol for which it is generally considered a replacement.

HDLC

High-Level Data Link Control. Popular ISO-standard, bit-oriented, link-layer protocol derived from SDLC. HDLC specifies an encapsulation method of data on synchronous serial data links.

In-Band Signaling

Tones that are carried along the same circuit path as the voice path that is being established by the signals.

IP

Internet Protocol. A network layer protocol that contains addressing information and some control information that allows packets to be routed.

IPX

Internetwork Packet Exchange. The Novell network layer (Layer 3) protocol that is similar to XNS and IP, and that is used in NetWare networks.

ISDN

Integrated Services Digital Network. Communication protocols proposed by telephone companies to permit telephone networks to carry data, voice, and other source material.

IVR

Interactive Voice Response. An Interactive Voice Response unit contains hardware and software to provide callers with the ability to enter information through their telephone key pad when prompted by programmed voice scripts stored in the IVR

IXC

Inter Exchange Carrier – All OCC’s and AT&T.

LAN

Local-Area Network. A network covering a relatively small geographic area (usually not larger than a floor or small building). Compared to WANs, LANs are usually characterized by relatively high data rates and relatively low error rates.

LATA

Local Access and Transport Area – The geographical areas which a local telephone company offers telecommunications services – local or long distance.

Leased Line

A transmission line reserved by a communications carrier for the private use of a customer. A leased line is a type of dedicated line.

LEC

Local Exchange Carrier – Either one of the 23 Bell operating companies or one of the 1400+ independent operating companies offering local phone service.

Line Conditioning

The use of equipment on leased voice-grade channels to improve analog characteristics, thereby allowing higher transmission rates.

Loopback Test

A test in which signals are sent and then directed back toward their source at some point along the communication path. Loopback tests are often used to test network interface usability.

Modem

Modulator-Demodulator. A device that converts digital signals into a form suitable for transmission over analog communication facilities and vice versa.

Multidrop Line

A communications line having multiple cable access points. Sometimes called a multipoint line.

NPA-NXX

Number Plan Area (area codes) – Exchange (codes within each area codes). Your area code and exchange (or prefix).

OSI

Open System Interconnection. An international standardization program created by ISO and CCITT (now ITU-T) to develop standards for data networking that facilitate multivendor equipment interoperability.

Packet

A logical grouping of information that includes a header containing control information and (usually) user data. Called a PDU by the OSI. The terms datagram, frame, message, and segment are also used to describe logical information groupings at various layers of the OSI reference model and in various technology circles.

Packet Switching

Networking method in which nodes share bandwidth with each other by intermittently sending packets. Contrasts with circuit switching and message switching.

PBX

Private Branch Exchange. A telephone switchboard on the user premises.

PCM

Pulse Code Modulation. Transmission of analog information in digital form through sampling and encoding the samples with a fixed number of bits.

PIC

Primary Interstate Carrier – Your choice of Long Distance Carrier.

POP

Point of Presence. The physical access point to a long distance carrier interchange.

POTS

Plain Old Telephone Service – Point of Terminating Service.

PRI

Primary Rate Interface. ISDN interface to primary rate access. Primary rate access consists of single 64-kbps D channel plus 23 B channels for voice or data.

PSC

Public Service Commission – State commissions regulating intrastate communications.

PUC

Public Utilities Commission – State commissions regulating intrastate communications.

PVC

Permanent Virtual Circuit. Generally, a virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and tear down in those situations where certain virtual circuits must exist all the time.

Quality of Service - A measure of performance for a transmission system that reflects its transmission quality and the availability of service.

RBOC

RJ-11

Standard 4-wire connectors for telephone lines.

RJ-45

Standard 8-wire connectors for IEEE 802.3 StarLAN networks. Also used as telephone lines in some cases.

RS-232

Popular physical layer interface. Now known as EIA/TIA-232.

SDLC

Synchronous Data Link Control. IBM bit-synchronous data link layer protocol that has spawned numerous similar protocols, including HDLC and LAPB.

SNMP

Simple Network Management Protocol. The Internet network management protocol.

SONET

Synchronous Optical Network. High-speed (up to 2.5 Gbps) synchronous network designed to run on optical fiber. Approved as an international standard in 1988. 

Tandem

A switching arrangement in which the trunk from the calling office is connected to the called office through an intermediate point.

TCP/IP

Transmission Control Protocol/Internet Protocol. The common name for the suite of protocols developed by the U.S. DoD in the 1970s to support the construction of worldwide internetworks. TCP and IP are the two best-known protocols in the suite. TCP corresponds to the transport layer (Layer 4) of the OSI reference model and provides reliable transmission of data. IP corresponds to the network layer (Layer 3) of the OSI reference model and provides connectionless datagram service.

Trunk Group

A group of circuits with the same type of protocol connecting two companies together (either switches or switch to CO).

Twisted Pair

Two insulated wires arranged in a regular spiral pattern. The wires can be shielded or unshielded.  UTP, Unshielded Twisted Pair.  Twisted pair is very common in voice and data networks.

UPS

Uninterrupted Power Source – An auxiliary power unit for a telephone system our computer system that will provide continuous power if you should lose commercial power.

WAN

Wide-Area Network. A network spanning a wide geographic area.