VoIP Glossary of Terms and Definitions

A VoIP glossary of definitions and terms used by VoIP providers follows. Please feel free to contact us if you have a question or would like for us to add a term to this list.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Analog:
A method of representing voice signals through a variation in the amplitude, frequency, or phase of an electrical signal. POTS telephone lines originally used analog transmission to gain access to the public telephone network.

Analog Telephone Adapter (ATA):
A piece of hardware that changes the analog signals from a regular phone into a format to transmit over the internet and vice versa at the receiving end. The ATA is normally used for most residential VoIP services.

Area code:
A three-digit code that represents a specific geographic calling area in North America.

Asymmetric Digital Subscriber Line:
(ADSL) is the most widely used form of DSL today. 'Asymmetric' meaning that data moves faster when downloading information than from uploading information.

The way the ADSL technology works is that it divides the available frequencies in a line based on the theory that users download more information than they upload. Therefore the connection speed from the internet to the user is three times or more faster than the speed from the user to the internet. As a result the user will benefit the most.

ADSL offers rates of 1.5 to 9 Mbps when downloading data and from 16 to 640 Kbps when sending. Data rates differ significantly depending on the distance from the telephone exchange, line quality and other factors.

Asynchronous Transfer Mode (ATM):
High bandwidth, low delay cell relay that uses fixed-size packets also know as cells. Used for numerous service types (such as data, voice, or video). ATM is the standard for fixed-length cell switching.

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B

Bandwidth:
A measure of the amount of data that can be transmitted during a set period of time. The bandwidth of a communications channel is often expressed in Kbps (kilobits per second) or Mbps (megabits per second).

Bit:
Binary digit, the smallest amount of information in a binary system, a 0 or 1 condition.

Bit Rate:
The number of bits that a communications channel can transmit in a fixed interval, typically measured in kilobits (1000 bits) per second (Kbsp).

Broadband:
A communications channel capable of transmission speeds equal to or greater than 256kKbps. Broadband describes two popular services (DSL and cable modem) that connect consumers and businesses to the internet.

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C

Cable modem:
A form of broadband service that runs over the consumer's cable television network transport line to provide access to the internet.

Caller Identification (ID):
A protocol through which a caller is identified to the recipient of the call.

Call Forwarding:
Forward calls to your cell, work or whatever phone you would like. Most VoIP providers allows you to change your call forwarding option through your web account. Some also allows the ability to change forwarding via your phone.

Call Waiting:
Allows you to accept a second call while you are on the line. You are notified by a tone that a second call is incoming. You can put the first caller on hold and accept the call or forward the caller to voicemail.

Central Office:
(CO) Telephone company facility where subscribers' lines are joined to switching equipment for connecting other subscribers to one another, locally and long distance.

Centrex:
A telephone service offered by a local telephone company from a local central office. Centrex is a single line telephone service delivered to individuals desks with many additional PBX like features such as call transfer, call forwarding, call hold, etc.

Circuit switching:
The conventional way of transporting a phone call over the PSTN. Numerous devices know as switches are employed by the carriers to create paths, or circuits, over which phone calls may be carried between a caller and a receiver.

Class 5 switch:
Telephone company switch.

Codec (coder/decoder):
A method used to compress and decompress speech or audio signals.

Competitive Local Exchange Carrier (CLEC):
Before the Telecommunications Act of 1996, the term

Computer Telephony:
Computer telephony represents the cooperative merger between telephony and data communications. It is a form of telecommunication that concentrates on the movement of both encoded and voice-related information from one point to another for automating transactions between machines and humans, or between machines.

Customer Premises Equipment (CPE):
Terminal equipment, supplied by either the telephone common carrier or by a competitive supplier, which is connected to the nationwide telephone network and resides on the customer's premises.

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Data Communications:
A form of telecommunications that concentrates on the movement of encoded information from one point to another. This information is readable by machines, such as modems, computers and fax machines as opposed to telephony, which is readable by the human ear.

Digital:
A fast, efficient method of representing voice signals through high and low pulses.

Digital Subscriber Line (DSL):
A common form of broadband service that converts a normal phone line into a high speed internet connection.

Digital Telephony:
An industry in which telephone calls are processed, routed, or sent digitally as opposed to through analog.

DS-O:
Digital Service, level 0. It is 64,000 bps, the worldwide standard speed for digitizing one voice conversation. There are 24 DS- channels in a DS-1.

DS-1:
The standard for 24 DS0 channels having an aggregate bandwidth of 1.536 Mbps A DS1 line is also known as a T1 line.

DS-3:
The standard for 672 DS0 channels having an aggregate bandwidth of 45 Mbps. ADS3 is also known as a T3 line.

DTMF:
Dual Tone Multi Frequency. A fancy term for describing push button or touch-tone dialing. In DTMF, when you touch a button on a push button dial, it makes a tone, which is actually the combination of two tones, one high frequency and one low frequency.

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E911:
An enhanced form of the standard number for emergency telephone calls made over the traditional PSTN in North America. E911 automatically provides, to the 911 call center agent, the caller's contact information, including name, address, and telephone number.

Email:
Electronically transmitted mail.

Ethernet:
The most popular packet based transmission protocol used for establishing data networks. Primarily used by corporations for LAN networking.

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Fax:
An electronically transmitted document

Feature:
Additional uses or applications of the telephone, the telephone line, or the network that carries the telephone call. Voice mail, call forwarding are examples of traditional features. VoIP telephony has all the traditional calling features plus a new generation of features that use the telephone and the network. For a list of the features click here.

Feature cost:
Charges associated with the implementation of calling features. Calling features have a cost associated with them, typically as additional monthly charges.

Firewall:
Hardware and software which limits the exposure of a computer or group of computers to an attach from an external location.

Frame:
A group of data bits in a specific format, with a flag at each end to show the beginning and end of the frame. The defined format enables network equipment to recognize the meaning and purpose of specific bits.

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Gateway:
Hardware that converts network packets or date from one network to a viable form for another network.

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Hard phone:
A VoIP enabled phone that has a RJ-45 LAN interface port to connect it to the Ethernet LAN.

Hosted VoIP:
A managed VoIP service similar in concept to the traditional Centrex mode.

Hypertext Transfer Protocol (HTTP):
The protocol used to transmit Web pages and their content including graphics, sounds, etc. across the web.

Hybrid fiber-coaxial:
HFC. The CSI that supports cable television, broadband services, and VoIP through cable modem and POTS telephony through a POTS telephone and adapter.

Hub:
Hub is a junction or common connection point where data arrives from one or more devices in a network and is sent out in one or more directions.

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IEEE 802.16:
The standard defining a form of WiFi known as WiMax designed to handle higher bandwidths over greater distances.

Incumbent Local Exchange Carrier (ILEC):
Carriers who owns the conventional, regulated cabling infrastructure in any given LATA.

In-state toll:
One of four traditional regulated toll carrier service categories, also known as intrastate.

Internet:
A global, publicly accessible, nonregulated, nonsecure network accessible from all five CSIs.

Internet Protocol (IP):
Method about how data is sent from one computer to another on the internet. Individual computers each has an IP address that identifies it from other computers on the internet.

Internet service providers (ISP):
An entity that provides internet service to end users.

International:
One of four traditional regulated toll carrier service categories.

Interstate toll:
One of four traditional regulated toll carrier service categories, also known as long distance.

Intrastate toll:
One of four traditional regulated toll carrier service categories, also known as in-state toll.

Intralata toll:
One of four traditional regulated toll carrier service categories, also known as local toll. Refers to calls in which the caller and receiver are in the same local access and transport area (LATA).

Intranet:
An internet-like network within a private organization. Those outside the network can gain access through a firewall or gateway if configured to allow such access.

IP soft phone:
Software the enables a computer to function as a VoIP telephone.

IP Telephony (Internet Protocol Telephony):
Technologies that allow voice calls to be converted into data packets and transmitted over a LAN or internet. Also know as VoIP, broadband and IP phone service.

ISDN:
Integrated Services Digital Network. A collection of standards which define interfaces for, and operation of, digital switching equipment, developed by carriers, equipment manufactures, and international standards organization. ISDN transports are capable of integrating data, voice, and video applications, but run slower than other transports available today.

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Kilo-bits per second (Kbps):
The number of one thousand bits transferred during one second. Used as a unit of measure to determine the transfer rate from one devise to another.

Kilo-Hertz (KHz):
A frequency measurement equal to 1000 cycles per second.

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Mega-bits per second (Mbps):
Millions of bits transferred during a second.

Mega-Hertz (MHz):
A frequency measurement equal to 1 million cycles per minute.

Modem:
Equipment that converts digital signals from a computer's serial port to the analog signals required for transmission over traditional telephone lines, and vice versa. Modem stands for modulator/demodulator.

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Network:
Computer networks connect all types of computers and computer-related things together -- terminals, printers, modems, etc..

Network Interface Card (NIC):
Provides the network device, such as a computer or a VoIP telephone, the means for connecting to a network.

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OC network:
Optical carrier network: One of the five CSIs, the OC network is implemented through fiber-optic cabling and extremely high bandwidth data transfers.

OC3:
An OC CSI transport that provides 155 Mbps of digital bandwidth.

OC12:
An OC CSI transport that provides 622 Mbps of digital bandwidth.

On-net:
In VoIP telephony, refers to calls carried on the customer's network.

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Packet:
A bundle of data, usually in binary form, organized in a specific way for transmission.

Packet Switching:
Sending data in packets through a network to a remote location. The data are subdivided into individual packets of data, each with a unique identification and individual destination address. This way each packet can take a different route and may arrive in a different order than it was shipped. The packet ID allows the reassembling of date in the proper sequence.

PBX:
Private Branch eXchange. A PBX is a small version of the phone company's larger central switching office. Used by larger companies to manage POTS-PSTN telephony services and calling features.

Phone Adaptor:
A piece of hardware that changes the analog signals from a regular phone into a format to transmit over the internet and vice versa at the receiving end. Also know as an analog telephone adaptor (ATA). The ATA is normally used for VoIP service.

Point-to-Point Protocol (PPP):
Point-to-point protocol (PPP) is a connection oriented protocol that is established between two communication devices that encapsulate data packets (such as Internet packets) for transfer between two communication points. PPP allows end users (end points) to setup a logical connection and transfer data between communication points regardless of the underlying physical connection (such as Ethernet, ATM, or ISDN).

PRI:
Primary Rate Interface. The ISND equivalent of a T-1 circuit. The PRI interface (that which is delivered to the customer's premises) provides 23Bchannels and one 64-Kbps D channel.

Public Switched Telephone Network (PSTN):
Also called the Plain Old Telephone Service (POTS). The oldest and largest communications network in the world and is controlled by telephone companies everywhere.

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Packet:
A bundle of data, usually in binary form, organized in a specific way for transmission.

Packet Switching:
Sending data in packets through a network to a remote location. The data are subdivided into individual packets of data, each with a unique identification and individual destination address. This way each packet can take a different route and may arrive in a different order than it was shipped. The packet ID allows the reassembling of date in the proper sequence.

PBX:
Private Branch eXchange. A PBX is a small version of the phone company's larger central switching office. Used by larger companies to manage POTS-PSTN telephony services and calling features.

Phone Adaptor:
A piece of hardware that changes the analog signals from a regular phone into a format to transmit over the internet and vice versa at the receiving end. Also know as an analog telephone adaptor (ATA). The ATA is normally used for VoIP service.

Point-to-Point Protocol (PPP):
Point-to-point protocol (PPP) is a connection oriented protocol that is established between two communication devices that encapsulate data packets (such as Internet packets) for transfer between two communication points. PPP allows end users (end points) to setup a logical connection and transfer data between communication points regardless of the underlying physical connection (such as Ethernet, ATM, or ISDN).

PRI:
Primary Rate Interface. The ISND equivalent of a T-1 circuit. The PRI interface (that which is delivered to the customer's premises) provides 23Bchannels and one 64-Kbps D channel.

Public Switched Telephone Network (PSTN):
Also called the Plain Old Telephone Service (POTS). The oldest and largest communications network in the world and is controlled by telephone companies everywhere.

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Real-time Transport Protocol (RTP):
A protocol for transmitting digital (voice, audio, video) real time over a network. Normally operates at the TCP/IP application layer.

RJ-11 connection:
A six conductor modular jack that is typically wired for four conductors, (i.e. four wires). The RJ-11 jack is the most common telephone jack in the world.

RJ-45 connection:
The RJ-45 is the 8-pin connector used for data transmission over standard telephone wire.

Router:
A network device that translates frame traffic into packetized traffic for the WAN or the Internet.

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User Datagram Protocol (UDP):
A method of communicating between computers which does not guarantee that every bit arrives at its end destination.

Unified Messaging:
The storage of different types of messaging formats in a single database for retrieval using a messaging system.

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Voicemail:
A system of recording self-consistent voice messages and storing them for retrieval and processing.

Voice over IP (VoIP):
A network service that supports carrying telephone calls over packetized networks.

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Wide Area Network (WAN):
A large network that connects more than one LANs using dedicated transport lines.

WiFi:
Also know as wireless fidelity. Wireless networking as specified in the IEEE 802.11 series of standards.

WiMax:
Wireless networking as defined in the IEEE 802.16 standard. Worldwide interoperability for microwave access. WiMax is demonstrating speeds in excess of 70 Mbps (more than six times the maximum speed of WiFi) over much greater distances (up to 30 miles).

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