A form of electronic information transmission that is accomplished using signals of varying frequency or amplitude. Voice and radio have traditionally been analog forms of communication. Modems are devices used to convert analog information into digital form for transfer over computer networks.


An analog telephone adaptor (ATA) is a device used to connect a standard telephone to a computer or network so that the user can make calls over the Internet. Internet-based long distance calls can be substantially cheaper than calls transmitted over the traditional telephone system, and ATAs are typically cheaper than specialized VoIP phones that connect directly to a computer's USB port.

Automatic callback

A PBX feature that lets employees calling from outside the office avoid long-distance charges. The employee places a short call to the PBX, which calls the individual back using an inexpensive (VoIP) calling plan. Confusingly, the term also refers to a feature that sets a phone to make multiple attempts to reach an unavailable number, alerting the caller when a connection is finally made.

ACD (Automatic Call Distributor)

An ACD manages incoming calls and handles them based on the number called and an associated database of handling instructions. Many companies offering sales and service support use ACDs to validate callers, make outgoing responses or calls, forward calls to the right party, allow callers to record messages, gather usage statistics, balance the use of phone lines, and provide other services.

ANI (Automatic Number Identification)

A service that provides the receiver of a telephone call with the number of the calling phone. The method of providing this information is determined by the service provider (such as AT&T, Verizon, Sprint, and so forth). The service is often provided by sending the digital tone multi frequency (DTMF) tones along with the call. Home users of ANI can screen callers. Emergency center dispatchers use ANI to save the caller having to report the information and, when necessary, to help locate callers. A telephone company's 9-1-1 service to a public safety point usually includes the ANI feature.

Auto attendant

A telephony feature that transfers incoming calls to the appropriate destination (an extension, voice mail, or recording, for example) without human intervention, by prompting callers to press buttons on their phone keypads or give voice responses such as "yes" or "no." An AA may also be called a virtual receptionist. Most AAs can route calls to landline phones, mobile phones, VoIP devices or other AAs.


The width of a communications channel. In analog communications, bandwidth is typically measured in Hertz. In digital communication, bandwidth is measured in bits per second (bps).


A short-range wireless connection standard. Its aim is to link a wide range of computers, electronics and telecoms devices. The technology uses a low-power, two-way radio link, which is built into a microchip. The Bluetooth standard is allowing for greater wireless Internet capability in the office and for consumers.


A type of communications transmission medium that has sufficient bandwidth to carry multiple voice, video or data channels at once.


The width of a communications channel. In analog communications, bandwidth is typically measured in Hertz. In digital communication, bandwidth is measured in bits per second (bps).


A short-range wireless connection standard. Its aim is to link a wide range of computers, electronics and telecoms devices. The technology uses a low-power, two-way radio link, which is built into a microchip. The Bluetooth standard is allowing for greater wireless Internet capability in the office and for consumers.


A type of communications transmission medium that has sufficient bandwidth to carry multiple voice, video or data channels at once.

Call Center

A physical place where customer and other telephone calls are handled by an organization, usually with some amount of computer automation. Typically, a call center has the ability to handle a considerable volume of calls at the same time, to screen calls and forward them to someone qualified to handle them, and to log calls.

Call Forwarding

Call forwarding is a telephone service that automatically routes the user's incoming calls to another number. The process may involve use of a virtual phone number. In a find me / follow me service, call forwarding may allow calls to be routed to the user at any location or to route calls through a number of different phone numbers or other applications, such as voice e-mail or text messaging.

Call logging

(also known as call recording or call monitoring) The practice of listening to, recording and assessing interactions between call center agents and callers. Used for staff training and development, customer quality control and liability protection. Contact center applications that use call recording include order verification, security and safety, customer service. Contact centers that implement call recording, logging and monitoring often see an increase in productivity, improved AHT (average handle time) and better customer relations.

Call Processing

The sequence of operations performed by a switching system from the acceptance of an incoming call through the final disposition of the call.

Caller ID

Permits the recipient of an incoming call to determine, even before answering, the number from which the incoming call is being placed.

Carrier Network

The proprietary network infrastructure belonging to a telecommunications service provider such as Verizon, AT&T or Sprint. Telecom carriers are authorized by regulatory agencies to operate telecommunications systems. Carrier networks are made up of large, complex configurations of hardware interconnected to provide communications services to people spread over large geographic areas.

CPE (Customer Premise Equipment)

A CPE device is telecommunications hardware located at the home or business of a customer (PBXs, phones, answering machines, etc.), which live on the customer’s premises.

Cloud Service

A cloud service is any resource that is provided over the Internet. The most common cloud service resources are Software as a Service (SaaS) Platform as a Service (PaaS) and Infrastructure as a Service (IaaS).


Any method of transmitting information through a binary system of zeros and ones.

DISA (direct inward system access)

Service provided by PBX systems that lets authorized personnel dial into the PBX from external phones, so they can, for example, place calls through the PBX.

Direct Inward Dialing (DID)

Direct Inward Dialing (DID) is a service of a local phone company or local exchange company that provides a block of telephone numbers for calling into a company's PBX system. Using DID, a company can offer its customers individual phone numbers for each person or workstation within the company without requiring a physical line into the PBX for each possible connection.

Find Me/Follow Me

Find me and follow me are two call forwarding services that are commonly used in conjunction with each other. Find me service allows the user to receive calls at any location; follow me service allows the user to be reached at any of several phone numbers. When that number is dialed the system routes the call through a user-defined list of numbers. The numbers may be called simultaneously or sequentially, either in a preferred order or in accordance with the user's scheduled activities and locations. Once the list has been called and no connection made, the system may route the call to voice mail. In a unified messaging system (UMS), find me / follow me may route messages among VoIP, voice email, fax and text messaging applications.

Hosted Service

A technology service that is offered over the web, rather than as a product (either software or hardware) that resides at the customer's premises.

HD Voice

A technology that provides better audio quality by delivering at least twice the sound range (wideband) of a traditional (narrowband) telephone call.

Instant Messaging (IM, IMing or AIM)

Instant messaging, often shortened to simply "IM" or "IMing," is the exchange of text messages through a software application in real-time. Generally included in the IM software is the ability to easily see whether a chosen friend, co-worker or "buddy" is online and connected through the selected service. Instant messaging differs from ordinary e-mail in the immediacy of the message exchange and also makes a continued exchange simpler than sending e-mail back and forth. Most exchanges are text-only, though popular services, such as AOL, MSN Messenger, Yahoo! Messenger and Apple's iChat now allow voice messaging, file sharing and even video chat when both users have cameras. For IMing to work, both users must be online at the same time and the intended recipient must be willing to accept instant messages, as it is possible to configure the IM client to reject chat sessions. An attempt to send an IM to someone who is not online, or who is not willing to accept IMs, will result in notification that the transmission cannot be completed. If the online software is set to accept IMs, it alerts the recipient with a distinctive sound, a window that indicates that an IM has arrived and allowing the recipient to accept or reject it, or a window containing the incoming message.

Interactive Voice Response (IVR)

The part of the auto attendant system that interacts with callers, gathers information and routes calls to the appropriate recipient. An IVR accepts a combination of voice telephone input and touch-tone keypad selection and provides appropriate responses in the form of voice, fax, callback, e-mail and perhaps other media.

Interexchange Carrier (IXC)

An interexchange carrier (IXC) is a telephone company that provides connections between local exchange s in different geographic areas. They're commonly referred to as "long-distance carriers."

ISDN (Integrated Services Digital Network)

An international communications standard that allows ordinary copper phone lines to transmit digital data very quickly. ISDN is generally a costly service and much faster than DSL.

IP PBX (Internet Protocol Public Branch Exchange)

Technology that provides a business with voice-over-Internet protocol (VoIP) services. An IP PBX converts analog voice input into digital signals to be sent over the Internet then converts digital voice input back into analog signals.

IP Multimedia System

The IP Multimedia Subsystem (IMS) is a concept for an integrated network of telecommunications carriers that would facilitate the use of IP (Internet Protocol) for packet communications in all known forms over wireless or landline. Examples of such communications include traditional telephony, fax, e-mail, Internet access, Web services, Voice over IP (VoIP), instant messaging (IM), videoconference sessions and video on demand (VoD).

IP Phone

A telephone handset that is specially designed for a VoIP phone system. IP Phones are not connected to traditional phone lines but instead have ports to connect to a broadband Internet connection. IP Phones are designed to support the many unique features that a VoIP network makes possible.

IP Telephony

Voice communications in which voice is converted into digital data packets and sent over the Internet using the Internet protocol.

Local Number Portability (LNP)

Local Number Portability (LNP) is the ability of a telephone customer in the U.S. to retain their local phone number if they switch to another local telephone service provider.

Plain Old Telephone Service (POTS)

A term sometimes used in discussion of new telephone technologies in which the question of whether and how existing voice transmission for ordinary phone communication can be accommodated. For example, ASDL and ISDN connections provide some part of their channels for "plain old telephone service" while providing most of their bandwidth for digital data transmission.


On the Internet, a point-of-presence (POP) is an access point from one place to the rest of the Internet.

Presence information

Information provided by a phone system to let users know if their contacts are available and via what method (by phone, e-mail, IM, and so forth).

Presence Technology

Presence technology is a type of application that makes it possible to locate and identify a computing device wherever it might be, as soon as the user connects to the network. IM is a common example.


Private Branch Exchange Digital or analog telephone switchboard located on the customer premises and used to connect private and public telephone networks.


All the tasks necessary to provide a user or an organization with telecommunications service; may be automated, so as to function with no assistance from a person.


(public switched telephone network) The world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned. It's also referred to as the Plain Old Telephone Service (POTS). It's the aggregation of circuit-switching telephone networks that has evolved from the days of Alexander Graham Bell ("Doctor Watson, come here!"). Today, it is almost entirely digital in technology except for the final link from the central (local) telephone office to the user.

Road Warrior

A contemporary term for professionals who spend a great deal of time traveling to work. Often applied to salespeople, managers, consultants and other workers who spend a great deal of time working outside of the office.

SIP (session initiation protocol)

A set of IP telephony signaling conventions, mostly used for VoIP, but usable for electronic delivery of any multimedia type.

SIP Trunking or Session Initiation Protocol (SIP) trunking

The use of voice over IP (VoIP) to facilitate the connection of a private branch exchange (PBX) to the Internet. In effect, the Internet replaces the conventional telephone trunk, allowing an enterprise to communicate with fixed and mobile telephone subscribers worldwide. (SIP is an IETF standard for initiating interactive multimedia user sessions; a trunk is a line or link that can carry many signals at once, connecting major switching centers or nodes in a communications system.) In order to take advantage of SIP trunking, an enterprise must have a PBX that connects to all internal end users, an Internet telephony service provider (ITSP) and a gateway that serves as the interface between the PBX and the ITSP. One of the most significant advantages of SIP trunking is its ability to combine data, voice and video in a single line, eliminating the need for separate physical media for each mode. The result is reduced overall cost and enhanced reliability for multimedia services. With SI


(software telephone) An application program that enables voice over Internet Protocol (VoIP) telephone calls from computing devices. In the enterprise, softphones are sometimes referred to as soft clients. Most softphone applications work in conjunction with a headset and microphone, a specialized VoIP Phone sometimes called a hardphone) or by using a device called analog telephone adapter which enables VoIP calling from a standard telephone handset.


A type of data connection that can transmit at 1.544 megabits per second – that is, very fast. Large companies often have a T1 line between their various locations to link large computer networks.


A teleconference is a telephone meeting among two or more participants involving technology more sophisticated than a simple two-way phone connection. At its simplest, a teleconference can be an audio conference with one or both ends of the conference sharing a speakerphone. With considerably more equipment and special arrangements, a teleconference can be a conference, called a videoconference, in which the participants can see still or motion video images of each other.

Trunk lines

The generally high-bandwidth communications links connecting two switching systems, such as the one at the telephone company central office and a PBX or between PBX systems. A trunk line carries many voice and data signals simultaneously.


An IP PBX's process of merging data from multiple calls into a single set of packets to reduce transmission overhead.

Unified Communications

According to the International Engineering Consortium, unified communications is an industry term used to describe all forms of call and multimedia/cross-media message-management functions controlled by an individual user for both business and social purposes. This includes any enterprise informational or transactional application process that emulates a human user and uses a single, content-independent personal messaging channel (mailbox) for contact access. Example: Unified messaging focuses on allowing users to access voice, e-mail, fax and other mixed media from a single mailbox independent of the access device.

Unified Messaging

Unified messaging (sometimes referred to as the unified messaging system or UMS) is the handling of voice, fax, and regular text messages as objects in a single mailbox that a user can access either with a regular e-mail client or by telephone. The PC user can open and play back voice messages, assuming their PC has multimedia capabilities. Fax images can be saved or printed. A user can access the same mailbox by telephone. In this case, ordinary e-mail notes in text are converted into audio files and played back. Unified messaging is particularly convenient for mobile business users because it allows them to reach colleagues and customers through a PC or telephone, whichever happens to be available. Some services offer worldwide telephone access.

Video Conference

A videoconference is a live connection between people in separate locations for the purpose of communication, usually involving audio and often text as well as video. At its simplest, videoconferencing provides transmission of static images and text between two locations. At its most sophisticated, it provides transmission of full-motion video images and high-quality audio between multiple locations.


Voice-to-text is a type of speech recognition program that converts spoken to written language.

VoIP/voice-over-Internet protocol

A system of computer software and hardware that allows voice communication to be delivered over the Internet, rather than over traditional copper telephone lines. Voice inputs are translated into data then delivered over the Internet to a receiving program that translates the data back into voice. This enables voice services to be combined and integrated with other data services. It can also reduce or eliminate the costs of long-distance phone charges over traditional telephony lines.

VoIP Phone

A VoIP phone is a telephone set designed specifically for use in a voice over IP (VoIP) system by converting standard telephone audio into a digital format that can be transmitted over the Internet, and by converting incoming digital phone signals from the Internet to standard telephone audio. A VoIP phone allows the user to take advantage of VoIP technology without involving a personal computer, although an Internet connection is required.

Web Conferencing

A form of real-time communications RTC in which multiple computer users, all connected to the Internet, see the same screen at all times in their Web browsers. Web conferencing allows users to carry on business meetings and seminars, make presentations, conduct demonstrations, provide online education and offer direct customer support. Control of the session can be passed among users so that any attendee can act as the main presenter. The most effective Web conferencing solutions require high-speed Internet connections at all user sites.

WAN (Wide Area Network)

A network of computers and other data devices that spans a much larger geographic area than a LAN or VLAN.

Wired network

A network of computers connected using hardware: physical cables and wires. Data such as instructions and information is transmitted between the connected devices over the wires.

Wireless network

A network of computers connected without using physical cables and wires. Computers and devices connected through a wireless network