Glossary of Terms

Support :: Glossary of Terms

We've compiled a list of common telecom and data terms to make it easy for you to find the definition you need.

Advance Replacement:

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A continuous electrical signal that varies in amplitude and/or frequency in response to changes of sound, light, heat, position or pressure. The sound of your voice causes an analog signal to be sent to the card via a telephone set. The voice signal is digitized by a CODEC chip located on a line card.

Aries I (NON-INL):

Telephones that require a power board and transformer when adding an add-on module.

Aries II (INL):

Telephones with INL have enhanced displays and a built-in power board.

Automatic Call Distribution (ACD):

Provides a means to distribute incoming calls among a number of answering positions in such a way that the calls are served in the order of their arrival and the work load presented to each ACD position is approximately equal.


The maximum amount of data that a network cable can carry, measured in bits per second (bps).

Catalyst Switch:

Series of Cisco workgroup switches that enhance the network performance of Ethernet client/server workgroups.

Central Office (CO):

Site where the telephone company terminates customer lines and locates the switching equipment interconnecting those lines.

Channel Service Unit (CSU):

Converts between one communications technology and another by providing the interface between the two. The CSU regenerates the signals received from the network.


Signals made up of discontinuous (on/off) pulses whose information is contained in the pattern of pulses. The digital signal is usually represented graphically as a square wave. This means that information internal to the system is relayed via digital signals. Voice signals must be converted from analog to digital and from digital to analog. The voice signal is digitized by a CODEC chip located in the set itself.


A 2 or 4 wire TIE line.


Baseband LAN specification invented by Xerox Corporation and developed jointly by Xerox, Intel and Digital Equipment Corporation. Ethernet networks use CSMA/CD and run over a variety of cable types at 10 Mbps. One of the most popular baseband LANs in widespread use. It is a carrier service multiple access collision detect (CSMA/CD) system using coaxial cable. Introduced in 1979, Ethernet Version II is compatible with the IEEE 802.3 CSMA/CD standard.

Fast Ethernet:

Any of a number of 100 Mbps Ethernet specifications. Fast Ethernet offers a speed increase ten times that of the 10BaseT Ethernet specification, while preserving such qualities as frame format, MAC mechanisms and MTU.


The ability to talk on the telephone without lifting up the handset.

In-line power (INL, Aries II):

Telephones with INL have enhanced displays and a built-in power board.

Level 1 Router:

Device that routes traffic within a single DECnet or OSI area.

Level 2 Router:

Device that routes traffic between DECnet or OSI areas. All Level 2 routers must form a contiguous network.

Local Area Network (LAN):

A short-distance data communications network (typically within a building or campus) used to link together computers and peripheral devices under some form of standard control.


Manufacturer Suggested Retail Price

Non-inline power (NON-INL, Aries I):

Telephones that require a power board and transformer when adding an add-on module.


Telephone with a speakerphone.

Primary Rate Interface (PRI):

In the United States, Canada and Japan, the PRI transmits data at a rate of 64 Kb/s over 23 B channels and sends signaling information at a rate of 64 Kb/s over one D.

Private Branch Exchange (PBX):

General term for a telephone system installed on the premise of a business customer to interconnect internal calls and calls from the outside.


Includes testing, cleaning, sanitizing, plastic recoating and painting-to certified specifications as good or better than OEM specs. After a final test, phones are repackaged with a new literature pack, coil cord, base cord and handset.


We offer Black Box Resale Services certified repair service for most Nortel, Avaya/Lucent, Executone, Siemens and Aspect products. For more information, please contact your sales representative.

Soft Keys:

The keys located by the display used to toggle through the display menus.


Digital service, 24 channels of 64 Kbps each.


TIE trunks connect two PBXs. TIE trunks may be incoming only, outgoing only or two-way combination.

Wide Area Network (WAN):

Data communications network that serves users across a broad geographic area and often uses transmission devices provided by common carriers. Frame Relay, SMDS and X.25 are examples of WANs. Compare with LAN and MAN.

Wide Area Telecommunications Service (WATS):

Tariffed voiceband direct distance dialing service with which a subscriber has separate options for inward and outward service between his location and specified geographic areas.

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Glossary of Terms

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