Find Out Telephony Jargon From A to Z

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Access Point
A station that transmits and receives data (sometimes referred to as a transceiver). An access point connects users to other users within the network and also can serve as the point of interconnection between the wireless LAN and a fixed wire network. Each access point can serve multiple users within a defined network area; as people move beyond the range of one access point, they are automatically handed over to the next one. A small wireless LAN may only require a single access point; the number required increases as a function of the number of network users and the physical size of the network. Access points operate on Wi-Fi or on the more recently approved DECT standard.
ACD (Automated Call Distribution)
Commonly used in Call Centers. The device that automatically answers all incoming calls, sends the calls to the first available agent, or, if all agents are busy, plays a recorded message and places the call into a queue until an agent becomes available.
Air Plenum Return
Newer building construction uses the open air space between the roof and a drop ceiling for circulating return air back to the heating/cooling system. This gives a tremendous savings over using traditional ducted returns. The down side is you must use Plenum Rated Cable within this space. Plenum Rated Cable costs roughly 3x that of non-plenum. If unsure of the return type, please check with your heating/cooling contractor to know the correct type of air return before you start cabling.
Analog Phone Line
Traditional telephone service whereby phone lines are delivered to the customer via copper wires. Each phone line requires two wires, and this service is typically associated with residential service or businesses that have fewer than 6 phone lines terminated into a Key System. This is also commonly called "POTS" for Plain Old Telephone Service.
ATA (Analog Telephone Adapter)
Device placed between an internet connection and a standard analog phone which turns a traditional telephony device into an IP device. Allows the user to utilize a traditional analog phone in a VoIP environment. On a VoIP system this is also known as a FXS port.
Automated Attendant (Auto Attendant)
A system that answers calls and provides the caller with enough information to chose who they need to speak with and then transfers the call to that group or individual. Some companies use this technology to make their business look larger and others use it as a backup to live answering.
Avaya is an industry leader in telephone systems from their small to medium business IP Office (or IPO for short) to very large enterprise in the Communication Manager (CM) solution.
A term used to define a headset type with two ear pieces. It usually has a headband attaching the two earpieces. This type is usually used in noisy environments when you want to block out everything except the telephone conversation.
A wireless technology that pairs Bluetooth enabled products. Extremly useful for headsets. For added convenience look for a dual purpose Bluetooth headset that connects to your office phone and cell phone at the same time.
Call Announce
This business feature allows an employee to call a specific phone and announce a caller or some other information. Most systems also feature Hands Free Response which allows the announced individual to respond back via speakerphone without even having to touch the phone.
Caller ID (CID)
The "called from" name and number that is transmitted and displayed over telephone lines. The caller has the ability to block delivery of this information by dialing 67 before dialing the destination number.
Cat 5 Cable (Category 5)
Category 5 cable includes four twisted pairs in a single cable jacket. This use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of interference is called crosstalk). It is most commonly used for 100 Mb/s networks. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge copper wires within the cables. Cat 5E is an enhancement which yields data rates of 155 Mb/s. Cat 5 or better cable should be used for all VoIP systems.
CLEC (Competitive Local Exchange Company)
Telephone Company that competes for business in the local telephone market against the incumbent telephone company (such as AT&T, Verizon, Qwest, Embarq & Windstream).
Data Bus
A collection of wires through which data is transmitted from one part of a computer to another. You can think of a bus as a highway on which data travels within a computer.
DECT (Digital Enhanced Cordless Telecommunications)
A digital wireless telephone technology that is expected to make cordless phones much more common in both businesses and homes in the future. Formerly called the Digital European Cordless Telecommunications standard because it was developed by European companies, DECT's present name reflects its global acceptance. Like another important wireless standard, Global System for Mobile communication (GSM), DECT uses time division multiple access (TDMA) to transmit radio signals to phones. Whereas GSM is optimized for mobile travel over large areas, DECT is designed especially for a smaller area with a large number of users, such as in cities and corporate complexes. A user can have a telephone equipped for both GSM and DECT (this is known as a dual-mode phone) and they can operate seamlessly.
DHCP (Dynamic Host Configuration Protocol)
A protocol for assigning dynamic IP address automatically to devices when they connect to the network. Dynamic addressing simplifies network administration because the software keeps track of IP address rather than requiring an administrator to manage the task. This is particularly helpful for laptops or other "visiting" devices when they want to connect to the Internet. Multiple DHCP Hosts is a common problem to troubleshoot on your LAN. For instance if you have a LAN set up and running a DHCP Host and you add a Wi-Fi router solely for the purpose of wireless access, you've just set up a conflict because these devices by default have DHCP Host enabled.
Dial Plan
A set of rules used by SIP devices to determine what digits are actually sent to the switch and what number are restricted. The simple Linksys PAP2 and SPA2100 have a single dial plan string that you can edit to allow 7 digit dialing in your local area and block 1-900 calls.
Dial Tone
The tone you receive when you lift the receiver and are connected to a telephone line. The tone is typically provided by the Telephone Company on traditional phone systems. In the case of IP, the telephone usually generates an imitation tone so the operation feels familiar to the user.
DID (Direct Inward Dial)
Inbound-only phone number assigned to a group of phone lines that allows a phone system to route to a unique location or person. A group of DIDs is often assigned to a single trunk group. This is typically offered on digital PRI lines or SIP lines and is the method that gives individual employees their own number. A PRI that can handle 23 simultaneous calls may have hundreds of DIDs pointing to this group, but the maximum number of inbound and outbound calls at any given time is still 23.
DNC (Do Not Call)
Make those nasty telemarketing calls go away!!! National registry created to let consumers block incoming telemarketing calls. If you choose to add your phone number to this list, it shows up on the registry by the next day. Telemarketers have up to 31 days to remove your number from their call lists. The Do-Not-Call Improvement Act of 2007 is now in place so you no longer have to register annually; your registration is permanent.
To register your numbers please visit
DSL (Digital Subscriber Line)
A generic name for digital lines that are provided by telephone companies to their local subscribers and that carry voice and high speed data simultaneously. DSL usually features higher download than upload capability since most home and small business use is surfing the web rather than uploading large files.
DSS/BLF (Direct Station Selection/Busy Lamp Field)
Buttons on a key telephone that can be programmed for an individual station so that pressing the button intercoms the station (DSS) and when the station is busy the button will light (BLF).
DTMF (Dual Tone Multi Frequency)
When using a touch tone dial pad you generate a sound made up of two separate tones at different frequencies. The Telephone Company recognizes these tones and dials the appropriate number or code. Supposedly the human voice cannot produce dual tones at different frequencies which is why AT&T adopted this standard; it prevents you from causing the phone to dial while you speak.
A set of related programs, located at a network gateway server that protects the resources of a private network from users from other networks. Basically, a firewall, working closely with a router program, examines each network packet to determine whether to forward it toward its destination. A firewall also includes or works with a proxy server that makes network requests on behalf of workstation users. A firewall is often installed in a specially designated computer separate from the rest of the network so that no incoming request can get directly at private network resources.
An analog port or external gateway on an IP system that allows for the connection of traditional analog telephone lines.
An analog port or external gateway on an IP system that allows for the connection of traditional analog devices such as a traditional analog telephone or fax.
A device that connects to the network and converts a signal to be transmitted via IP. In telephony the classic use of a gateway is to convert POTS or analog lines to IP. As an example, we use a gateway to bring SIP Trunks into an xBlue Key System.
A term that represents 1 Billion Bytes per second of data throughput on a network.
Handset Cord
The coiled wire that connects the handset to the telephone. Usual modular and may be replaced by any modular make or color.
A business feature where a call is temporarily held by the KSU or Server and the caller typically hears music or an announcement during this time. Hold is used while sending the caller to another extension, while setting up a conference call, or while answering another call or simply when looking up information.
Home Run
No, this is not what Alex Rodriguez hits on a daily basis for our Yankees! It is a wiring structure where each device has a wire run all the way back to the KSU or Server. Traditional TDM and Digital phone system require home run wiring. Our IP solution and our xBlue do not.
Hunt Group
Series of telephone lines organized so that when the first line is busy, the next line is "hunted" and so on until a free line is found. This is the principal differentiator between residential and business service with Hunt being a business feature.
The term used for the local independent companies that sell, install and support telephone systems. The better interconnects have a dealership with the products they represent and have trained technicians. These are very useful if you do not have the knowhow to install or manage your LAN.
IP (Internet Protocol)
A protocol that specifies the way data is broken into packets and the way those packets are addressed for transmission. Unlike traditional telephone lines which create a straight path from caller to recipient; IP uses the best available path at any given moment to move data packets between point A & point B. The beauty of IP is that the sending end and receiving end communicate success in sending and receiving to insure all data packets are delivered. A really great concept of IP is that of self healing. If a route is broken and the data packets cannot be delivered an alternate route is automatically selected.
ISDN (Integrated Services Digital Network)
In the telephony world, ISDN was a set of standards introduced for digital lines (trunks). ISDN comes in two flavors, PRI (Primary Rate Interface) which is transported over a T1 (group of 24 digital trunks) where the channels 1-23 are utilized for voice, and the 24th channel is utilized for call control between the PBX and the Telephone Company (23B+D). The second is BRI (Basic Rate Interface) which is transported over a single pair of wires and give 2 voice channels and the 3rd channel utilized for call control (2B+D). PRIs a commonly used in the US and countries that follow the US while BRIs are commonly used outside the US as a substitute for POTS Lines.
KSU (Key Service Unit)
The traditional control unit for a Key Systems. Usually consisting of a central processor and card support for telephone lines and proprietary digital key stations.
A multi-line phone system that does not have a central controller like a KSU or PBX. These phones are usually found in the SOHO environment. They use the line voltage of the telephone line to determine if the line is idle or in use (voltage sensing). These are basic system that are generally sold as a single phone with multiple lines.
LAN (Local Area Network)
The components that make up the data transfer mechanism for your office. The components include the cabling, the switches or hubs, routers, gateways, WiFi and servers.
A synonym for delay is an expression of how much time it takes for a packet of data to get from one designated point to another. In most usages latency is measured by sending a packet that is returned to the sender and the round-trip time is considered the latency. 150ms is the generally accepted maximum latency target for successful VoIP. You can measure latency by pinging any address from your CMD prompt. In the below example I pinged and after 4 returns see an average latency of 63ms. You may alternatively ping a specific IP address.
The acronym for "Liquid Crystal Display". The most commonly used technology for numeric/text or graphical displays.
Line Cord
The straight modular cord that connects the phone to the wall jack. The standard phone line cord typically only has 2 conductors and an RJ11 plug. On an IP telephone the term "patch cord" is generally used as this is a data grade cord with 8 conductors and an RJ45 plug.
A term used to define a headset type with only one ear piece. It usually has a headband attached to the single earpiece. This type is usually used in a quiet office so the user can also carry on conversatons while not on the telephone.
MPLS (Multiprotocol Label Switching)
Newer networks utilize this protocol to speed traffic and better control of QOS and management. This protocol adds switching labels to the packets for faster movement between sites. Works with a variety of transport types.
Network Switch
A hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model. Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub. VoIP traffic requires the use of Networks Switches. Hubs are not acceptable.
Noise Cancelling
A technology used in headsets to reduce the ambient noise that a sensative headset microphone would otherwise pick up. You must pick a headset that specifically states NC or Noise Cancelling.
This business feature allows an employee, using the handset of their phone, to make an announcement or "page" the rest of the company via the speakers in inactive phones or via overhead speakers or via a combination of both. This is generally a one way conversation only. Page is typically used when you don't know exactly where to find someone.
Similar to hold except the call is held by the Server or KSU and to retrieve the call you need to know the Park Number or have Park buttons on the phone. Typically used in a larger PBX system when a receptionist does not know where to find an individual, in this case the receptionist would Park and then Page the individual.
Patch Panel
A wiring device that connects individual Cat5 cable runs to a modular RJ-45 Jack providing for easy connection between the cable plan and network devices such as the Ethernet Switch, Router and Server. Simple patch cords are used to interconnect these devices to the cable plan. We also do wiring and this is one area that you may want Telco Depot to handle.
Phantom Ringing
The annoying ring back you get when a telephone line rings and you answer to find nobody there. This occurs after you hang up on a line and the telephone company does not recognize the signal as a disconnect but instead places a call on

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