Telecom Terminology and Acronyms
Telecommunications terminology can be confusing, and business telephone definitions can even change from company to company! We want you to understand exactly which service you’re receiving and why, so America’s Phone Guys has put together a glossary of our favorite telecommunications terminology to take the mystery out of the VoIP services we provide. Have any questions about what you’re reading? Give us a call!
Abandoned Cable – Any cabling, from Riser closet to server room to end-user, which is no longer being used, is the wrong cable type (i.e. riser in a plenum ceiling) or not tagged for future use. It is defined as Installed communications cable that is not terminated at both ends at a connector or other equipment and not identified For Future Use with a tag.
Abnormal Termination Report – Monitoring per-user quality-of-service metrics in real-time.
ACD (Automatic Call Distributor) – A system that handles incoming call traffic, sending calls to the first available station within predefined groups. If all stations are busy then a recorded message is played, and the call is put in a queue until a station becomes available.
Acoustic Coupler – A device that allows a conventional telephone handset to feed its signal into a modem, as opposed to direct couplers, which feed the modulated/demodulated signal directly into the phone line.
Acoustic Echo Canceller – All speakerphones have some form of adaptive echo canceller that produces a synthetic replica of the potential echo to subtract from the transmit audio. Most units have a center clipping echo suppressor to remove the residual echo from the transmit signal. The goal of the acoustic echo canceller is to reduce the amount of direct and reverberant loudspeaker coupling to the microphone to prevent echo. To achieve this, the algorithms used in today’s devices require an audio system that is feedback stable.
Acoustic Echo Return Loss – AERL – The minimum loss experienced by a sound in traveling from the loudspeaker to the microphone in a conference room. It is expressed in dB or decibels. A 0-dB loss corresponds to a perfectly reflective room or to very close coupling between loudspeaker and microphone. In practice, AERL figures can range from 0 to -30 dB, with a poor room having the former figure.
Acoustic Echo Return Loss Enhancement – AERLE – The maximum echo cancellation provided by the acoustic canceller. Typical figures will vary from 6 to 18 dB. The larger the number the better. It is important to note whether the figure is quoted with the center clipper enabled or disabled. If quoted with center clipper disabled, it is a true measure of the cancellation provided by the echo canceller rather than the attenuation provided by the center clipper.
Acoustic Modem – A modulator-demodulator unit that converts data signals to telephone tones and back again.
Air Blown Fiber (ABF) – Small, flexible plastic microduct tubing installed prior to the installation of individual or multiple optical fibers that are blown through the microduct using compressed air.
Analog – A transmission method using continuous electrical signals, varying in amplitude or frequency in response to changes of sound, light, position, etc. impressed on a transducer in the sending unit. The opposite of analog is DIGITAL.
Analog-to-Digital – A/D Conversion – The conversion of an analog signal into a digital equivalent. An A/D converter samples or measures an input voltage and outputs a digitally encoded number corresponding to that voltage.
Analog Transmission – Transmission of a continuously variable signal as opposed to a discrete signal. Physical quantities such as temperature are described as analog while data characters are coded in discrete pulses and are referred to as digital.
Asynchronous Transfer Mode (ATM) – Not the money machine! This is an international CCITT standard for high-speed [broadband] packet-switched networks that operates at digital transmission speeds above 1.544 Mbps. This communications protocol specifies how diverse kinds of traffic are transformed into standardized packets, which can be managed uniformly within the network.
Attendant – An operator of a PBX console or telephone switchboard.
Attenuation – A reduction in power or amplitude of the transmitted signal. In cables, it is generally expressed in decibels per unit length.
Audio Bridge – An audio bridge connects the telephones at remote sites, equalizes the noise distortion and background noise for a live audio teleconference.
Audio Teleconferencing – Two-way electronic voice communication between two or more groups, or three or more individuals, who are in separate locations.
Audiographic – Teleconference system which uses narrowband telecommunications channels (telephone lines or subcarriers); transmits audio and graphics. Graphics can be transmitted by facsimile transceivers (transmitter-receiver), computers (text or graphic display), or electronic drawing systems (such as electronic blackboard) which allow a participant to draw or write on an electronic screen which is transmitted to a remote site where participants can see it.
Automatic Ring Back – Normally, when a line is busy, you try redialing every few minutes. With automatic ring back, a code is dialed into the telephone keypad to enable the phone to notify you with a ring when your call goes through. Your phone will ring with a distinctive ring, so you know it’s an automatic ring back. When you pick up the phone, it redials the number, so you can complete your call.
Auxiliary Disconnect Outlet (ADO) – A device usually located within the tenant or living unit used to terminate the ADO cable or backbone cable.
Backbone Cabling – Cable and connecting hardware that comprises the main and intermediate cross-connects, as well as cable runs that extend between telecommunications rooms, equipment rooms, and entrance facilities.
Balance – An indication of signal voltage equality and phase polarity on a conductor pair. Perfect balance occurs when the signals across a twisted-pair are equal in magnitude and opposite in phase with respect to ground.
Balanced Signal Transmission – Two voltages, equal and opposite in phase with respect to each other, across the conductors or a twisted-pair (commonly referred to a tip and ring).
Bandwidth – The relative range of frequencies that can be passed without distortion by a transmission medium. Greater bandwidths mean a higher information-carrying capacity of the transmission circuit. Bandwidth, usually measured in Hertz, is assessed as the number of bits that can be transferred per second.
Basic Rate Interface – BRI – The basic subscriber loop for one or two users, which delivers two 64 kbps B channels and one 16 kbps D channel over a standard twisted-pair loop. Each circuit-switched B channel can transmit voice or data simultaneously. The D channel transmits call control messages and user packet data.
B-ISDN (Broadband integrated services digital network) – An evolving CCITT international standard for the second generation of integrated services digital networks. Broadband ISDN services will be carried on fiber-optic networks that employ packet switching in a standardized fashion to integrate voice, data, monochrome, and color facsimile images and one-way and two-way monochrome and color video for local and long-distance transmission.
Bonding – The permanent joining of metal parts to form an electrically conductive path that will assure electrical continuity and the capacity to conduct safely any current likely to be imposed on it.
Break Test Access – Method of disconnecting a circuit that has been electrically bridged to allow testing on either side of the circuit without disturbing cable terminations. Devices that provide break test access include disconnect blocks, bridge clips, plug-on protection modules, and plug-on patching devices.
Bridge – A device, which interconnects three or more telecommunication channels, such as telephone lines. A telephone conference audio bridge links three or more telephones (usually operated assisted). Usually a meet-me audio bridge or provides a teleconference direct dial access number. Both connect remote sites and equalize noise distortion.
Bridged Tap – The multiple appearances of the same cable pair or fiber at several distribution points. Also known as parallel connections.
Bridges, Gateway, Routers – Devices that convert LANs to other LANs, computers, and WANs by allowing systems running on different media (copper wire, fiber optics, etc.) and protocols (rules to communicate).
Bridging – A means of providing through connections between conductors or pairs that are terminated on connecting blocks. These through connections are commonly provided by means of individual metallic bridging clips or multiple bridging clips that are housed in a plastic insulator.
Bridging Amplifier – An amplifier connected directly into the main trunk of the CATV system. It serves as a sophisticated tap, providing isolation from the main trunk, and has multiple high-level outputs that provide signal to the feeder portion of the distribution network. Synonymous with Bridger and distribution amplifier.
Broadband – Communications channels that are capable of carrying a wide range of frequencies. Broadcast television, cable television, microwave, and satellite are examples of broadband technologies. These technologies are capable of carrying a great deal of information in a short amount of time but are more expensive to use than technologies like telephone, which require less bandwidth.
Broadband (Wideband) distribution systems – A telecommunications medium that carries high-frequency signals; includes television frequencies of 3 to 6 megahertz. Broadband distribution systems work like cable TV, in that up to twenty channels are available from a single coaxial cable. A main trunk cable will originate at the control room and run down the hallways of the viewing area. Smaller cables can tie into the main cable at any point along its length. Any room that is near the main cable run can have access to all the channels on the system. Normal television sets are used, and a variety of channels can be received by simply changing channels on the television set.
Broadband Network – A local area network (LAN) residing on coaxial cable capable of transporting multiple data, voice and video channels.
Building Distributor – The international term for intermediate cross-connect. A distributor in which the building backbone cable(s) terminates and at which connections to the campus backbone cable(s) may be made.
Bundled Cable –An assembly of two or more cables continuously bound together to form a single unit prior to installation (sometimes referred to as loomed, speed-wrap or whip cable construction).
Bus Topology – A linear configuration where all network devices are placed on a single length of cable. It requires one backbone cable to which all network devices are connected.
Busy Override – Allows the calling party to break into an ongoing conversation.
Cabling – A combination of cables, wire, cords and connecting hardware used in telecommunications infrastructure.
Call Logging – This feature captures, records and provides cost information for telephone usage. It can track both inbound and outbound calls, call ring outs, etc.
Call Blocking – The ability to block any phone number or by caller ID.
Call Forwarding on Busy – Allows incoming calls to be redirected to a mobile or other number when your line is busy.
Call Forwarding on Absence – Also known as Forwarding on No Answer – Allows an incoming call to be redirected to a mobile number of other telephone number when you are away from your office phone.
Call on Hold – Allows incoming calls to be suspended and/or retrieve a call placed in suspension.
Call Park – Allows you to put a call on hold at one telephone set and continue the conversation from any other telephone set once you’ve entered the “park code”.
Call Pick-Up – Allows you to answer someone else’s telephone from your extension.
Call Routing – This is a system that can route callers to specific people or departments based on input from callers.
Call Threshold Monitoring – Real-time monitoring of calling or called numbers with large amounts of call attempts.
Call Timer – Clocking phone conversation connection time.
Call Transfer – Sending an existing call to another telephone extension.
Call Waiting – A feature that provides audible or visual indicators to let a single-line-phone user know that there is another call waiting.
Caller ID – Transmits a phone number and possibly name to the called party’s telephone equipment during the ringing signal.
Camera – In television, an electronic device utilizing an optical system and a light-sensitive pick-up tube to convert visual images into electrical impulses. Camera Control Unit # CCU: An electronic device that provides all the operating voltages and signals for the proper set up, adjustment and operation of a television camera.
Camp-On – In PBX and hybrid environments, a method of putting an incoming or outgoing call intended for a busy extension or line into a hold-like state where it remains until a line becomes available.
Campus Backbone – Cabling between buildings that share telecommunications facilities.
Campus Distributor – The international term for main cross-connect. The distributor from which the campus backbone cable emanates.
Card – A flat piece of rigid material bearing electronic components and the printed circuitry that interconnects them. Cards typically have one point where connections to other cards or components are made.
Category – The North American standards for cabling describes mechanical properties and transmission characteristics of unshielded twisted-pair (UTP) cables and screened twisted-pair (ScTP) cables and assigns a unique number classification (Cat 3, Cat 5e, Cat 6).
Category – The international standard for cabling and local standardization documents define cabling component categories based on transmission performance parameters such as attenuation and NEXT loss, over a specified frequency range. Component categories are Cat 5, Cat 6 and Cat 7.
Central Office (CO) – A facility of a telecommunications common carrier where calls are switched. In local area exchanges, central offices switch calls within and between the 10,000-line exchange groups that can be addressed uniquely by the area code and first three digits of a phone number.
Channel – The end-to-end transmission path connecting any two points at which application specified equipment is connected. Equipment and work area cables are included in the channel.
Circuit – Means of two-way communication between two or more points. In communication systems, an electronic, electrical, or electromagnetic path between two or more points capable of providing a number of channels.
Class of Service Restrictions – This feature can prevent callers from placing certain types of calls such as long-distance, international or 900 numbers.
Classification – Application classes for cabling have been identified for the purpose of ISO/IEC 11801 standard:
• Class A: cabling is characterized up to 100kHz
• Class B: cabling is characterized up to 1 MHz
• Class C: cabling is characterized up to 16 MHz
• Class D: cabling is characterized up to 100 MHz
• Class E: cabling is characterized up to 250 MHz
• Class F: cabling is characterized up to 600 MHz
• Optical Class: optical fiber links are characterized from 10 MHz and above.
CLEC (Competitive Local Exchange Carrier) – Your local telephone service provider who is one of the new-generation providers rather than an RBOC or Independent. A CLEC is really just an Independent, albeit one formed after the divestiture of AT&T. See LEC.
CLID – Calling Line Identification. This is the ISDN and SS7 equivalent of Caller ID; I.E. the number of the calling party.
Codec (Coder/Decoder) – a device that transforms analog input into a digitally coded output and transforms digital signals into analog output. They are most commonly found in videoconferencing systems because of videoconferencing’s intensive ISDN usage.
CO Lines – The lines connecting your office to the CO (Central Office or telephone company).
Collapsed Backbone – A centralized network contained in one device. The network is said to be collapsed and made to fit into a box. Individual networks are connected to this central device and can then communicate with one another.
Combination Trunk – A trunk (channel) which can both make and receive calls. This generally refers to analog ground start or loop start trunks, although the term can be applied to ISDN BRI or PRI channels as well. Each combination trunk normally has a telephone number, although they are frequently part of a hunt group and only one number may be published for that group. Also called a Both Way Trunk. This is not the same as a Two-way DID trunk.
Common Carrier – A government-regulated private company offering telecommunications services or communications facilities to the general public.
Computer Conferencing – Allows individuals at different locations to communicate with each other through computers. This could be through a chat room, e-mail, a classroom environment created by software. It might include text, audio, video, or shared work-spaces on which all participants can type or draw.
Conference Call – Having more than 3 people on the same call, depending on the type of business telephone system or Conference Bridge this can be up to hundreds of people.
Consolidation Point – A location for interconnection between horizontal cables that extend from building pathways and horizontal cables that extend into work area pathways.
Consult Hold – Allows you, while on an established call, to place the original call on hold & call any other station inside or outside the telephone system.
Computer Telephone Integration – Voice, dialing, e-mail, web, CM, call information display, phone control (answer, hang up, hold, conference, etc.), phone and data transfers, call center phone control (logging on; after-call work notification). Call recording and fax.
Cross-Connect – A facility enabling the termination of cables as well as their interconnection or cross-connection with other cabling or equipment. Also known as a distributor.
Cross-Connection – A connection scheme between cabling runs, subsystems, and equipment using patch cords or jumpers to attach to connecting hardware on each end.
Crosstalk – Noise or interference caused by electromagnetic coupling from one signal path to another.
CSD (Circuit Switched Data) – A dial-up data communications channel, which, once established, looks like a transparent data pipe. Also, the type of ISDN service required to utilize this capability of an ISDN circuit. In contrast to CSV.
CSV (Circuit Switched Voice) – A dial-up communications circuit for voice-grade communication. Also, the type of ISDN service required to use this capability of an ISDN circuit. In contrast to CSD.
Custom Greetings – Separate greetings for internally originated calls or by caller ID, record & save multiple greetings, voice mail greetings, dialing instructions, out of the office, on vacation, personal greetings, etc. Allowing you to quickly switch default greetings.
Custom ISDN – An ISDN protocol which pre-dates National ISDN-1. In most cases, National ISDN-1 is also available. The Northern Telcom DMS-100 switch supports “Custom DMS ISDN”. The AT&T/Lucent 5ESS switch supports “Custom Point-to-Point” (PTP) and Custom Point-to-MultiPoint (PMP). The ISDN protocol has no relation to where one may call. The Telos Zephyr and TWOx12 do not support PMP.
Data Compression – Techniques to reduce the amount of computer memory space or transmission resources required to handle a given quantity of data usually achieved through the application of mathematic algorithms to the data transformation process.
D Channel – The signaling and data transmission channel (specified in ISDN standards) used to transmit network control signals for setting up phone calls.
Daisy Chain – A way to connect computers – one after another along a single line.
Data Communications – The movement of encoded information by means of electrical or electronic transmission systems. OR The transmission of data from one point to another over communications channels.
Dedicated Line – Leased telecommunications circuits that are devoted to a specific application; a circuit designated for exclusive use by two users; i.e., for interactive portion of a teleconference.
Dedicated System – Videoconferencing equipment, transmission circuits, and teleconferencing facilities that are permanent and used on a regularly scheduled basis as opposed to rented for a one-time or ad hoc event.
Delay Skew – The difference in propagation delay between the fastest and slowest pair in a cable or cabling system.
Demarcation Point (DP or Demarc) – A point at which two services may interface and identify the division of responsibility. Normally the point to which the phone company will deliver service to within a building.
Desktop Click-to-Dial – Computer telephone integration allowing you to click on the person or number in your computer that you wish to call & the call being placed on your telephone.
DHCP / DNS Phone Activation – Management of the phone system via IP Network & Centralized Monitoring.
Dial-Up Teleconferencing – Using public phone line to connect with a teleconference, either with or without operator assistance.
DID Extension or DID Station – A specific phone within a PBX which can be called from the public telephone network without going through an attendant or auto-attendant.
DID Number – A phone number used to route calls from the telephone network to a specific phone in a PBX (the DID extension). DID requires special DID trunks or ISDN PRI “two-way DID” trunks. Blocks of DID numbers (typically 10 or 20) are purchased from the LEC or CLEC for use on the PBX. The number of DID numbers usually substantially exceeds the number of trunks in the system.
DID Trunk – A Direct Inward Dialing Trunk. A trunk (channel) which can only receive calls. A group of telephone numbers (DID numbers) are associated with a given trunk group, however, there is no one-to-one correspondence between the individual channels and these numbers. The PBX uses the DID number given it by the phone company to route the channel to the correct DID extension within the PBX extension. This allows some or all PBX stations to receive calls directly without going through an attendant (or auto-attendant) Note that there are almost always more DID numbers than there are DID trunks.
Digital Switch – Equipment used to set up pathways between users for transmission of digital signals.
Direct Inward Dialing – Call routing directly to the desired telephone extension without the need for an operator or attendant.
Direct Inward System Access – The ability to access internal features from an outside telephone line.
Distributor – The term used for the functions of a collection of components (e.g. patch panels, patch-cords) used to interconnect cables.
Do Not Disturb – Prevents calls from ringing an extension, sending calls directly to voice mail or another phone.
Ducting (Pathway) – A facility (i.e. conduit) for the placement and protection of telecommunications cables – same as raceway.
Duplex – simultaneous transmission in both directions; sometimes referred to as full duplex to differentiate it from half-duplex, which is alternating transmission in each direction. Transmission in only one direction is called simplex transmission.
E-mail/Voice Mail Integration – This function allows you to receive e-mail containing your voice mail messages in sound .wav files.
Encoder/Decoder – A device used to transform signals from an originating terminal into groups of digital pulses representing letters, numerals, or specific symbols, and transform incoming digital pulses into the form required by the receiving terminal.
Entrance Facility – An entrance to a building for both public and private network service cables (including antennae), including the entrance point at the building wall and continuing to the entrance room or space. Entrance facilities are often used to house electrical protection equipment and connecting hardware for the transition between outdoor and indoor cable.
Equipment Cable – A cable or cable assembly used to connect telecommunications equipment to horizontal or backbone cabling.
Equipment Room, Telecommunications – A centralized space for telecommunications equipment that serves the occupants of the building or multiple buildings in a campus environment. An equipment room is considered distinct from a telecommunications room because it is considered to be a building or campus serving (as opposed to floor serving) facility and because of the nature or complexity of the equipment that it contains.
Ethernet – Baseband protocol and technology developed by Xerox and widely supported by manufacturers; a packet technology that operates at 10 Mbps over coaxial cable and allows terminals, concentrators, work stations, and hosts to communicate with each other.
Facilities – Transmission lines, switches and other physical components used to provide telephone service.
Fax – A method of transmitting graphics or text documents over a telecommunications facility. The image is scanned at the transmitter and reconstructed at the receiver to be duplicated on paper.
FC Connector – A type of optical fiber connector identifiable by its round, screw-operated locking nut. It is usually metal. Its ruggedness leads it to be widely used in test equipment.
FDDI Fiber Distributed Data Interface – 1. Transports data up to speeds of 100 Mbps. 2. FDDI is a high-speed (100Mb) token ring LAN.
Fiber Optics – Technology based on thin filaments of glass or other transparent materials used as the medium for transmitting coded light pulses that represent data, image and sound. Fiber optic technology offers extremely high transmission speeds.
Fiber Optic Transmission – A communication scheme whereby electrical data is converted to light energy and transmitted through optical fibers.
Firestop – A material, device, or assembly or parts installed in a cable pathway at a fire-rated wall or floor to prevent passage of flame, smoke or gases through the rated barrier (e.g. between cubicles or separated rooms or spaces).
Floor Distributor – The international term for horizontal cross-connect. The distributor used to connect between horizontal cable and other cabling subsystems or equipment.
Follow-Me – The phone extension is configured with a list of numbers for a person. When a call is received, the call routes to each number on the list until either the call is answered, or the list is exhausted.
Four-Wire Circuit – A circuit that has two pairs of conductors (four wires), one pair for the send channel and one pair for the receive channel; allows two parties to talk and be heard simultaneously.
Frame Relay – A high-speed interface between switches and T1 or T3 multiplexers. Frame relay is a connection-oriented interface that initially will be incorporated into private T1 and T3 multiplexers. T1 and T3 multiplexers equipped with frame relay will provide a packet-oriented, HDLC-framed interface to routers and X.25 packet switches. The packets will be routed to the proper destination by the multiplexers. Minimal protocol processing enables frame-relay multiplexers to achieve high throughput. Initially, permanent virtual circuits will be supported; later, it is likely that switched virtual circuits services may also be provided by frame relay. The major advantage of frame-relay-equipped multiplexers is that only a single connection is required from the customer premises equipment (routers or X.25 packet switches) to the multiplexer. Also, with frame relay support in multiplexers, users contend for bandwidth provided via the multiplexer, and thus line cost efficiencies can be improved.
Gain – An increase in signal power in transmission from one point to another; usually expressed in decibels.
Gateway – A network element interconnecting two otherwise incompatible networks, network nodes, sub-networks or devices.
Ground – A conducting connection, whether intentional or accidental, between an electrical circuit (telecommunications) or equipment and earth, or to some conducting body that serves in place of the earth.
Hands-Free Operation – Using a speaker or microphone built into the phone base instead of the handset.
Headset Options – Hands-free operation using a wired or wireless handset; some include hands-free lifting systems so that you won’t even need to lift the receiver off the phone base.
Hertz – A measure of frequency as defined in units of cycles per second.
Home-Run Cabling – A distribution method in which individual cables are run directly from the horizontal cross-connect to each telecommunications outlet. This configuration is also known as star topology.
Horizontal Cabling – The cabling between and including the telecommunications outlet and the horizontal cross-connect.
Horizontal Cross-Connect – A cross-connect of horizontal cabling to other cabling, e.g. horizontal, backbone or equipment.
Hot Desk (Hotelling) – A method of supporting unassigned seating in an office environment or temporary physical operation of a workspace.
Hub – Equipment that serves as the centralized connection point for a network or portion thereof. Hubs are used for multiplexing, multi-port bridging functions, switching and test access. They can be either passive or active and are not considered to be a part of the cabling infrastructure.
Hunt Group – When a line called is busy, this system sends the call to the next available line. This is used to distribute calls from a single telephone number to a group of phone lines.
Hybrid – A combination of two or more technologies or a multiline business telephone system combining the manual line selection of a key system and the automatic line selection of a PBX system.
Hybrid Cable – An assembly of two or more cables, of the same or different types or categories, covered by one overall sheath.
ILEC (Incumbent Local Exchange Carrier) – A local Exchange Carrier that entered the marketplace before the enactment of the 1996 Telecom act; i.e. a telephone company which is neither an Indie nor an RBOC.
Inbound – The direction of a signal relative to the hub of a local area network (LAN) or other telecommunications system. Inbound signals would be traveling from originating points other than the primary hub in the reverse direction to the hub.
Intelligent Hub – A hub that performs bridging and routing functions in a collapsed backbone environment.
Interbuilding Backbone – Telecommunications cable(s) that are part of the campus subsystem that connect one building to another.
Interconnect – A company or vendor selling customer premises equipment, generally PBXs and other types of office telephone systems. An interconnect company is typically an independent distributor of products from more than one manufacturer.
Interconnection – A connection scheme that provides direct access to the cabling infrastructure and the ability to make cabling system changes using equipment cords.
Interactive Voice Response (IVR) – A generic term for transaction systems allowing phone callers to use an ordinary tone-dialing telephone to interact with a computer through speech or dialed instructions. Each response by the caller triggers another recorded message until the transaction is completed.
Intermediate Cross-Connect – The connection point between a backbone cable that extends from the main cross-connect (first-level backbone) and the backbone cable from the horizontal cross-connect (second-level backbone).
ISDN (Integrated Services Digital Network) – Switched network providing end – to -end digital connectivity for simultaneous transmission of voice and/or data over multiple multiplexed communications channels and employing transmission and out-of-band signaling protocols that conform to internationally defined standards.
Intercom – Two-way talk paths over a phone base speaker with or without announcement, for group announcement or limited public dialogue with everyone in the group.
Intercom Groups – Two-way talk paths over a phone base speaker with or without announcement, for group announcements, or limited public dialogue with everyone in the group.
Inter-Exchange Carrier – IXC – Carriers that can carry inter-LATA traffic. Long-distance telephone companies such as AT&T.
Jack – A connecting device to which a wire or wires of a circuit may be attached, and which is arranged for the insertion of a plug.
Jumper Wire – An assembly of twisted-pairs without connectors on either end used to join telecommunications links at a cross-connect.
Key Telephone System – A multiline telephone system offering a limited range of features; key systems are popular among smaller businesses as their main telephone system. They are also found in large businesses as a form of extension to their big primary phone system. Key systems are characterized by manual selection of outgoing lines, their small size, and relatively low price.
Last Number Redial – Placing a call to the last number dialed by pressing a reduced number of keys.
LATA – Local access and transport area of a telephone company.
Leased Lines – A term used to describe the leased or rented use of dedicated lines from point to point. Lines could include fiber optic cables, telephone cables, microwave or other transmission systems.
LEC – Local exchange carrier of a telephone company. Carriers that can carry only intra-LATA traffic. Local telephone companies such as CenturyTel, Verizon, Integra, etc.
Line – An electrical connection between a telephone service provider’s switch (LEC or CLEC) and a telephone terminal or Key system. An electrical connection between a telephone service provider’s switch and another switch is called a trunk. Note that some type of physical line offers more than one channel. I.E. a BRI circuit has 2 channels, called B channels.
Line Appearance – A button/lamp on the telephone base linked to a phone line that indicates availability. You can see the status of the line by looking at the phone. When the lamps are lit, they indicate lines are in use, on hold, ringing, or available.
Line Appearance – Shared – Allows multiple stations to share line appearance(s), extension number and manage calls as a group. Everyone in the group can see the status of their select incoming lines.
Line Card – The circuit in the Telco switch to which your line is connected. On an ISDN circuit, the line card performs a role analogous to the NT1 in adapting and equalizing the circuit.
Link – An end-to-end transmission path provided by the cabling infrastructure. Cabling links include all cables and connection hardware that comprise the horizontal or backbone subsystems. Equipment and work area cables are not included as part of a link.
Local Area Network (LAN) – A geographically limited data communications system for a specific user group consisting of a group of interconnected computers, sharing applications, data and peripheral devices such as printers and CD-ROM drives intended for the local transport of data, video, and voice.
Local Exchange Carrier (LEC) – The local regulated provider of public switched telecommunications services.
Local Loop – The communications channel, usually a physical line, between the subscriber’s location and his local central office. Also known as the subscriber loop.
Loop Start – A method of demanding dial tone from the central office by completing an electrical pathway between the outbound and return conductors of a telephone line. Single-line telephone instruments employ Loop start, for example.
Main Cross-Connect – A cross-connect for the first level backbone cables, entrance cables, and equipment cables.
Measured Service – Term generally associated with providing local telephone service on a usage-sensitive basis with calls priced based on two or more of the following usage elements: distance, duration, frequency, and time of day. It is the opposite of flat-rate pricing.
Meet-Me Bridge – Meet-Me Teleconferencing – A type of telephone bridge that can be accessed directly by calling a certain access number; provides dial-in teleconferencing. The term “meet-me bridging” refers to the use of this type of bridge.
Message Rate – A form of usage-sensitive pricing for local telephone service where usage charges are figured by counting the calls and multiplying the number of calls made by the established per-call charge. An alternative to flat-rate and measured pricing.
Message Waiting Indicator – A lamp on the telephone set base indicating you have received a phone call and have received a new voice mail message.
Modem (Modulator-Demodulator) – An electronic device that allows computers to communicate over standard telephone lines. It transforms digital signal into an analog signal and transmits to another modem which then reconstructs the digital signal from the analog signal.
Modular Jack / Plug – A telecommunication outlet/connector for wire or cords. Modular jacks can have 4, 6 or 8 contact positions, but not all the positions need to be equipped with contacts.
Multiple Mailbox Greetings – Ability to create separate greetings for internally originated calls and externally originated calls, or by caller ID. You can record and save multiple greetings, welcome greetings, voice mail greetings, dialing instructions, out of the office messages, on vacation notifications, personal greetings, etc.
Multiplexed Channel – A communications channel capable of serving several devices, or users, at once
Multiplexing – An electronic or optical process that combines a large number of lower-speed transmission lines into one high-speed line by splitting the total available bandwidth of the high-speed line into narrower bands (frequency division), or by allotting a common channel to several different transmitting devices, one at a time in sequence (time division). Multiplexing devices are widely employed in networks to improve efficiency by concentrating traffic.
Music On Hold – Playing recorded music or messages to fill the silence for callers placed on hold.
Name Announcement – A method to audibly announce an identified caller. The caller name is determined by making a query to a database with phone numbers and corresponding line owners.
Network – Any system designed to provide one or more access paths for communications between users at different geographic locations that may include designs for voice, data, facsimile images and/or video images.
Network Architecture – A set of design principles defining the protocol, functions and logical components of a network and how they should perform.
Network Demarcation Point – The point of interconnection between the local exchange carrier’s telecommunication facilities and the telecommunications systems wiring and equipment as the end user’s facility. This point is located on the subscriber’s side of the telephone company’s protector or the equivalent thereof in cases where a protector is not required.
Network Interface – The physical point in a telephone subscriber’s home or place of business where the telephone devices and/or inside wiring of the subscriber are connected to the transmission lines of the local telephone service provider.
Night Service – After hours incoming calls are automatically redirected by the switchboard to telephones or central voice mail.
Off-Hook – A telephone set in use – the handset is removed from its cradle, thus sending an electrical signal to the central office that a circuit needs to be opened.
Off-Line – The condition where a terminal or device capable of active connection with the facilities of a computer or communications networks is in the disconnected or idle state.
Off-Premises System – Refers to a teleconferencing room or equipment located outside of a user organization’s facility; e.g., a video teleconferencing room operated by a vendor and available to the public for a fee.
On-Hook – The normal state of the phone in which the handset rests in the cradle and the circuit to the central office conducts no electrical signal.
On-Line – The condition where a terminal or device capable of active connection with the facilities of a communications network or computer is in the active or connected state; a unit functioning under the continual control of a computer.
Outbound – Direction of a signal relative to the hub of a local area network (LAN) or other telecommunications system. Outbound signals would be traveling away from the primary hub in the forward direction to the extremities of the system.
Outbound Caller ID number DID or Company – Feature allows control over what’s displayed on the outbound caller ID with certain types of telephone lines.
Outbound Call Restrictions – Prevents callers from placing certain types of calls such as long-distance, international or 900 numbers.
Outlet / Connector – A connecting device in the work area on which horizontal cable terminates.
PABX – Private Automatic Branch Exchange: A private automatic telephone exchange, usually located at the user’s site, that routes and interfaces the local business telephones and data circuits to and from the public telephone network.
Packet Switched Network – A digital data transmission network that uses packet switching technology.
Packet Switching – A digital data transmission method that divides messages and files into standard-size pieces – called packets – that are switched across networks individually and then reassembled at their destination.
Paging – A service designed to deliver numeric or alphanumeric messaging to a person whose location is uncertain – paging services make use of radio communications.
Patch Cord – A length of cable with connectors on one or both ends used to join telecommunications links at a cross-connect.
Patch Panel – Connecting hardware that typically provides means to connect horizontal or backbone cables to an arrangement of fixed connectors that may be accessed using patch cords or equipment cords to form cross-connections or interconnections.
Plenum – A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
Point-to-Multipoint – A teleconference broadcast from one location to several receiving locations (also known as downlink sites.)
Point-to-Point Teleconference between two locations. Point-to-Multipoint – one location to many sites.
Port – An interface location on a computer or communications system that provides a point of access for peripheral equipment, such as printers, voice mail, C.O. Lines, etc.
POTS Lines (Plain Old Telephone Service Lines) – Basic telephone lines whose primary purpose is the transmission of human speech.
Power Back-Up – Provides power to the phone system during power outages.
PRI – Primary rate interface – PRI is a CCITT-defined ISDN trunking technology that delivers 64 kbps clear channels and standardized out-of-band signaling. PRI can serve customer premise equipment (CPE) such as a PBX, LAN gateway, or host computer or can serve as a trunk interface between central offices.
Private Branch Exchange (PBX) – A private switching system usually serving an organization, such as a business, is located on the customer’s premises. It switches calls both inside a building or premises and outside to the telephone network and can sometimes provide access to a computer from a data terminal.
Prompt – When the host system asks you to do something and waits for you to respond. For example, if you see “login:” it means type your user name.
Propagation Delay – The amount of time that passes between when a signal is transmitted and when it is received at the opposite end of a cable or cabling.
Public Switched Network – Any switching system that provides a circuit-switched to many customers.
Punch Down – A method for securing wire to a quick clip in which the insulated wire is placed in the terminal groove and pushed down with a special tool. As the wire is seated, the terminal displaces the wire insulation to make an electrical connection. The punch down operation may also trim the wire as it terminates. Also called a cut-down.
Queue – A “holding room” for data or voice communications that are waiting to be processed by either the system or human intervention.
Redundancy – Having back-up systems available to provide continuous service in the case of a failure in the main system
Remote Access – Sending and receiving data to and from a computer through communications links such as phone lines.
Remote Call Forwarding – Similar to call forwarding. Calls from a local telephone number can be forwarded to long-distance numbers (in another city for example) without the caller be charged for long-distance fees.
Remote / Duplicate Extensions –Shared line presence on multiple phones with simultaneous ringing.
Remote Location – Ability to use phone system and access phone system features external to the physical phone system location.
Ring Conductor – A telephony term used to describe one of the two conductors in a cable pair used to provide telephone service. This term was originally coined from its position as the second (ring) conductor of a tip-ring-sleeve switchboard plug.
Ring Network – A local area network in which devices are connected in a closed-loop or ring as opposed to a bus network.
Ring Tones – Customizable audible alerts, representing various telephone activities. Allows audible distinguishing of internal calls, external calls, and can be assigned to specific phone numbers or activities.
Secretary Functions – Permits a station user to answer an internal or external incoming call on the Boss’ line, announce, consult, transfer back to the boss or Voice Mail by re-depressing the boss’ line. This is generally used to screen calls.
Serial Transmission – Sending pulses (information) one right after another. The opposite would be a parallel transmission.
Shared Message Boxes – A group mailbox set up so any member of the group, usually the first available, can retrieve the message.
Shielded Twisted-Pair (SSTP) – A cable surrounded by a metallic braid, foil or both and bound in a single plastic sheath containing balanced twisted-pair conductors that are individually shielded.
Singlemode Optical Fiber – An optical fiber that will allow only one mode to propagate; this fiber is typically step-index fiber.
Small Form Factor – An optical fiber connector and adapter that provides for two strands of fiber in a surface area similar to an unshielded twisted-pair (RJ-style) plug and socket.
SMDR (Station Message Detail Reporting) – Information recorded by a computer attached to the phone system, providing cost accounting information such as the number of calls, both local and long-distance, made from an extension during a certain time period.
Special Event Teleconferencing – Teleconference that uses facilities that are temporarily linked for a specific event; implies a temporary satellite network for one-way video and two-way audio.
Speed Dial – A feature on PBX phones allowing users to dial programmed numbers by simply pressing one button (or entering a two or three-digit code).
Speaker Phone – Speaker and microphone built into the telephone base, used for hands-free communication, paging and intercom communication.
Station – Simply another word for the telephone. For example, the telephone station may be one of many extensions on a PBX system.
Station Hunting – A feature allowing an incoming call to a busy phone to be routed to the next idle phone in a pre-determined group of phones.
Station-to-Station – Avoids carrier rate charges, calling internal extensions by pressing a reduced number of keys, usually the last 3 or 4 digits of a DID number.
Structured Cabling – A building or campus telecommunications-cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems.
Switched Line – A circuit, which is routed through a circuit-switched network.
Switching – Connecting the caller to the called party.
T-1 – A digital transmission link capable of handling 1.544 Megabits per second.
T-3 – 28 T-1 lines (See T-1).
Telecommunications – Any transmission, emission or reception of signs, signals, writings, images, sounds or information of any nature y cable, radio, visual, optical or other electromagnetic systems.
Telecommunications Room (TR) – An enclosed space for housing telecommunications equipment, cable terminations, and cross-connect cabling used to serve work areas located on the same floor. The telecommunications closet is the typical location of the horizontal cross-connect and is considered distinct from an equipment room because it is considered to be a floor serving (as opposed to building or campus serving) facility.
Teleconference – A conference, which links people by audio and/or video through telecommunications.
Telephony – The process of converting sounds into electrical impulses for transmission over a connecting medium such as wires, fiber optics or microwave.
Terminal – The point of connection between a telephone line and an operative device. Also, sometimes terminal refers to the operative device, such as a computer terminal.
Tie Line – A telephone line which is dedicated to connecting two points and which requires a minimum human intervention to achieve communication.
Time & Date Display – LCD display of time, date and length of conversation.
Tip Conductor – A telephony term used to describe the conductor of a pair that is grounded at the central office when the line is idle. This term was originally coined from its position as the first (tip) conductor of a tip-ring-sleeve switchboard plug.
Token Ring -A method of controlling which of several work stations in a Local Area Network is transmitting at a particular time.
Toll Restriction – A method of controlling which employees, if any, have access to telephone lines for which a toll may be charged to the employer.
Topology – The physical or logical layout or links and nodes in a network. These include star, ring and bus configurations.
Transfer: Announce / Consult – Allows you to speak with the receiving party before executing a call transfer.
Transfer: Blind / Ringing – Allows you to transfer a call without intervention, without speaking to the receiving party.
Transition Point (TP) – A location in the horizontal cabling subsystem where flat under carpet cabling connects to round cabling.
Trunk – A communication line between two switching systems. The term switching systems typically includes equipment in a central office (the telephone company) and PBXs. A tie trunk connects PBXs. Central office trunks connect a PBX to the switching system at the central office.
Trunk Group – A number of telephone channels, which are functionally related. Most common is the Hunt Group. Other common types include Incoming Trunk Groups and Outgoing Trunk Groups.
Turnkey – A ready-to-go telephone system installed by the vendor, including both hardware and software.
Twin-Axial Cable – Two commonly insulated conductors, covered by a metallic shield and enclosed in a cable sheath.
Twisted Pair – Two copper wires twisted around each other. The twists vary in length and reduce induction.
Two-Way DID Trunk – An ISDN PRI (or T1) line equipped for direct inward dialing. Most trunks are related to a given phone number, either alone or as part of a hunt group. In the case of a “normal” (i.e. analog) DID Trunk a group of phone numbers are associated with that DID trunk (or group of trunks) and incoming calls include the DID Number, so the PBX can route that call to the correct DID Extension. This is exactly how ISDN PRI functions, with the DID information coming in over the D Channel. There is a significant difference between a normal DID Trunk and a Two-way DID trunk over ISDN PRI. For one thing, ISDN PRI is digital. More importantly, you cannot dial out over a true DID trunk and you can dial out over a PRI.
Unshielded Twisted-Pair (UTP) – A cable with multiple pairs of twisted insulated copper conductors bound in a single sheath.
Video Teleconference – A meeting involving at least one uplink and a number of downlinks at different locations. Electronic voice and video communication between two or more locations. It can be a fully interactive voice and video or two-way voice and one- way video. It includes full-motion, compressed, and freeze-frame video.
Voice Mail – Answering machine where messages are digitized and recorded for future retrieval.
Voice Mail System – Voice messages stored in personalized mailboxes associated with the user’s phone number for future retrieval.
VM Message Archiving – Ability to save a voice mail message past the normal retention period.
VM Forwarding – Enables users to forward received messages to another user’s voice mailbox.
VM Remote Access – Accessing your voice mail from another phone or a telephone that is outside your phone system.
VM Time / Date Stamp – System appends time and date messages to received and recorded messages.
Videoconferencing – Video teleconferencing (See teleconferencing).
Voice Digitization – Converting analog signals (voice) into binary bits for storage and transmission.
Voice Mail Broadcasting List – Sends one message to one or more other user’s voice mailboxes.
Voice Mailbox Group – Send or forward voice mail messages to multiple voice mailboxes or a voice mailbox group.
Voice Paging – A one-way path of announcement sent over a phone base speaker or external overhead speaker, with little or no announcement, for individual or group announcement.
Voice Response – A computer allowing users interaction via touchtone telephone. Users navigate the system with the help of digitally read menus.
WAN (Wide Area Network) – A network that extends LANs to other LANs, typically over a wide geographical area using communications lines provided by a common carrier.
WATS Line -Wide Area Telecommunications Service – A type of telephone service in which subscribers pay a base rate rather than a charge per call. An in-WATS line allows anyone in a designated area to phone an 800 number and pay nothing for the call. An out-WATS line allows users to place outgoing long-distance calls.
Work Area Cable – A cable assembly used to connect equipment to the telecommunications outlet in the work area. Work area cables are considered to be outside the scope of cabling standards.
Work Order – Also known as a trouble ticket, this form is what identifies the work to be performed at a customer location by a technician.
Telecom Terminology and Acronyms in Portland OR and Vancouver WA
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