Unified Communications Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing unified communications and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

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  • #

    .Tel

    .Tel is a top-level domain (TLD) intended for universal text naming and navigation in Internet-based communications... (Continued)

  • 4K video resolution

    4K video resolution is high-definition (HD) video that has four times the resolution of 1080p HD video.

  • A

    analog telephone adapter (ATA)

    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.

  • Avaya

    Avaya is an American technology company that specializes in business communications services, such as unified communications (UC), and contact center (CC).

  • C

    call admission control (CAC)

    Call admission control (CAC) is the practice or process of regulating traffic volume in voice communications, particularly in wireless mobile networks and in VoIP (voice over Internet Protocol, also known as Internet telephony)... (Continued)

  • call control

    Call control is a process that is used in telecommunications networks to monitor and maintain connections once they have been established.

  • call deflection

    Call deflection is a feature of voice over IP (VoIP) that automatically redirects a call from the called endpoint to another endpoint (usually a voice mailbox) when the called endpoint is busy.

  • call detail record (CDR)

    A call detail record (CDR) in voice over IP (VoIP) is a file containing information about recent system usage such as the identities of sources (points of origin), the identities of destinations (endpoints), the duration of each call, the amount billed for each call, the total usage time in the billing period, the total free time remaining in the billing period, and the running total charged during the billing period.

  • call forwarding

    Call forwarding is a telephone service that automatically routes the user's incoming calls to another number.

  • call signaling

    Call signaling is a process that is used to set up a connection in a telephone network.

  • Carrier Sensitive Routing (CSR)

    Carrier Sensitive Routing (CSR) is a network solution that allows Voice over Internet Protocol (VoIP) subscribers to determine and manipulate the routing of individual calls... (Continued)

  • centrex (central office exchange service)

    Centrex (central office exchange service) is a service from local telephone companies in the United States in which up-to-date phone facilities at the phone company's central (local) office are offered to business users so that they don't need to purchase their own facilities.

  • Cisco Webex

    Cisco Webex is a cloud-based collaboration suite comprised of Webex Meetings, Webex Teams and Webex Devices.

  • CLEC (competitive local exchange carrier)

    In the United States, a CLEC (competitive local exchange carrier) is a telephone company that competes with the already established local telephone business by providing its own network and switching.

  • click-to-talk (CTC)

    Click-to-call (CTC), also called click-for-talk, is a technology that converts Web traffic into voice telephone connections using VoIP (Voice over IP)...(Continued)

  • cloud telephony (cloud calling)

    Cloud telephony, also known as cloud calling, is a type of unified communications as a service (UCaaS) that offers voice communication services through a third-party host.

  • codec

    A codec is either a hardware device or a software-based process that compresses and decompresses large amounts of data used in voice over IP, video conferencing and streaming media.

  • CoIP (communications over Internet Protocol)

    CoIP (communications over Internet Protocol) is a set of standards defining the transmission of multimedia over the Internet. CoIP can be considered an expansion of VoIP (voice over Internet Protocol) to include text, images, video and other forms of digital data as well as voice information... (Continued)

  • communication portal

    A communication portal is a service that allows individuals, businesses, schools and government agencies to share information from diverse sources using unified communications (UC) media. The most common modes are e-mail, texting, Voice over IP (VoIP) and conventional telephone services... (Continued)

  • communications platform as a service (CPaaS)

    Communications platform as a service (CPaaS) is a cloud-based delivery model that allows organizations to add real-time communication capabilities, such as voice, video and messaging, to business applications by deploying application program interfaces (APIs).

  • communications-enabled business processes (CEBP)

    Communications-enabled business processes (CEBP) is the integration of communications capabilities into software-enabled business procedures, applications and technologies... (Continued)

  • D

    data transfer rate (DTR)

    Data transfer rate (DTR) is the amount of digital data that is moved from one place to another in a given time.

  • dedicated line

    A dedicated line is a telecommunications path between two points that is available 24 hours a day for use by a designated user (individual or company).

  • dial peer (addressable call endpoint)

    A dial peer, also known as an addressable call endpoint, is a device that can originate or receive a call in a telephone network.

  • dial peer hunting

    Dial peer hunting is a feature of voice over IP (VoIP) systems in which the device at the originating router attempts to find an alternative addressable call endpoint if it cannot establish a connection to the intended endpoint.

  • Distributed Universal Number Discovery (DUNDi)

    Distributed Universal Number Discovery (DUNDi) is a peer-to-peer system for translating phone numbers and internal extensions to voice over IP (VoIP) addresses.

  • E

    E911 (Enhanced 911)

    In the United States, E911 (Enhanced 91 is support for wireless phone users who dial 911, the standard number for requesting help in an emergency.

  • ear and mouth (E&M)

    Ear and mouth (E&M) is a technology in voice over IP (VoIP) that uses a traditional telephone handset with an earphone (or earpiece) for listening to incoming audio and a microphone (or mouthpiece) for transmitting audio.

  • eavesdropping

    Eavesdropping is the unauthorized real-time interception of a private communication, such as a phone call, instant message, videoconference or fax transmission.

  • Erlang B

    Erlang B is a modeling formula that is widely used in call center scheduling... (Continued)

  • Erlang C

    Erlang C is a traffic modeling formula used in call center scheduling to calculate delays or predict waiting times for callers... (Continued)

  • Ethernet/IP (Ethernet Industrial Protocol)

    Ethernet/IP (Ethernet Industrial Protocol) is a network communication standard capable of handling large amounts of data at speeds of 10 Mbps or 100 Mbps, and at up to 1500 bytes per packet.

  • F

    find me / follow me

    Find me and follow me are two call forwarding services that are commonly used in conjunction with each other... (Continued)

  • G

    G.711

    G.711 is the default pulse code modulation (PCM) standard for Internet Protocol (IP) private branch exchange (PBX) vendors, as well as for the public switched telephone network (PSTN).

  • G.722

    G.722 is a standard for high-quality digital voice communications that is expected to lead to increased use in Voice over Internet Protocol (VoIP)... (Continued)

  • G.723.1

    G.723.1 is a standard for digital communications that employs 16-bit pulse-code modulation (PCM) at 5.3 or 6.3 kilobits per second (Kbps) with an input sample rate of 8 kilohertz (kHz)... (Continued)

  • G.729

    G.729 is a standard for Internet Protocol (IP) private branch exchange (PBX) vendors, as well as for the public switched telephone network (PSTN)... (Continued)

  • gatekeeper

    A gatekeeper is a management tool for H.323 multimedia networks.

  • greenfield deployment

    In networking, a greenfield deployment is the installation and configuration of a network where none existed before, for example in a new office.

  • H

    H.245

    H.245 is a protocol for the transmission of call management and control signals in packet-based networks using H.323 equipment.

  • hairpinning

    In general telecommunication, hairpinning is returning a message from an origin endpoint back in the direction it came from as a way to get it to its destination endpoint.

  • hop off

    Hop off is a term used in telecommunications that refers to a point at which a signal or call leaves a network and moves to another network.

  • hop on

    In telecommunications, hop on refers to a point at which a signal or call enters a network from another network.

  • hundred call second or centum call second (CCS)

    The hundred call second -- also known as the centum call second (CCS) -- is a unit of telecommunications traffic density that is the equivalent of one call (including call attempts and holding time) in a specific channel for 100 seconds in an hour.

  • hyperconnectivity

    Hyperconnectivity is a state of unified communications (UC) in which the traffic-handling capacity and bandwidth of a network always exceed the demand... (Continued)

  • I

    IAX (Inter-Asterisk Exchange Protocol)

    IAX (Inter-Asterisk Exchange Protocol, pronounced "eeks") is a communications protocol for setting up interactive user sessions... (Continued)

  • ILEC (incumbent local exchange carrier)

    An ILEC (incumbent local exchange carrier) is a telephone company in the U.S. that was providing local service when the Telecommunications Act of 1996 was enacted.

  • inbound call

    An inbound call is one that a customer initiates to a call center or contact center... (Continued)

  • inbound call center

    An inbound call center is one that exclusively or predominately handles inbound calls (calls initiated by the customer) rather than outbound calls... (Continued)

  • Indefeasible Right of Use (IRU)

    In telecommunications, Indefeasible Right of Use (IRU) is the effective long-term lease (temporary ownership) of a portion of the capacity of an international cable.

  • instant messaging (IM)

    Instant messaging, often shortened to IM or IM'ing, is the exchange of near real-time messages through a stand-alone application or embedded software.

  • Internet Protocol

    The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet.

  • IP PBX (private branch exchange)

    An IP PBX is a private branch exchange (telephone switching system within an enterprise) that switches calls between VoIP (voice over Internet Protocol or IP) users on local lines while allowing all users to share a certain number of external phone lines.

  • IP telephony (Internet Protocol telephony)

    IP telephony (Internet Protocol telephony) is a general term for the technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, and other forms of information that have traditionally been carried over the dedicated circuit-switched connections of the public switched telephone network (PSTN).

  • J

    Jingle protocol

    Jingle is a family of signaling protocols for initiating and managing peer-to-peer (P2P) media sessions over the Internet. 

  • jitter

    Jitter is the time variation between when packets leave one system and reach another, affecting real-time communications like VoIP and video conferencing.

  • jitter buffer

    In voice over IP (VoIP), a jitter buffer is a shared data area where voice packets can be collected, stored, and sent to the voice processor in evenly spaced intervals.

  • K

    keyphone (K/P or key station)

    Commonly used by a company within its private automatic branch exchange (PABX) telephone system, a keyphone (abbreviated as K/P, sometimes called a key station) is a telephone with the extra buttons and the intelligence to allow incoming calls to be transferred to other extensions.

  • L

    layer 3

    Layer 3 refers to the Network layer of the commonly-referenced multilayered communication model, Open Systems Interconnection (OSI).

  • leased line

    A leased line is a bidirectional telephone line that has been rented for private voice, data exchange or telecommunication use.

  • long-distance carrier

    A long-distance carrier is a telephone company that provides connections between local exchanges in different geographic areas.

  • M

    media gateway

    A media gateway is any device, such as a circuit switch, IP gateway, or channel bank that converts data from the format required for one type of network to the format required for another.

  • Message Session Relay Protocol (MSRP)

    Message Session Relay Protocol (MSRP) is a protocol for exchanging a series of related instant messages across an IP network in the context of a session.

  • Microsoft Teams

    Microsoft Teams is cloud-based team collaboration software and part of the Office 365 software suite.

  • N

    National Call Fee Access (NCFA)

    In the U.K., National Call Fee Access (NCFA) is a Number Translation Service (NTS) that enables a caller that calls a non-geographic telephone number beginning with 0870 or 0871 to be charged what is known as the national call rate.

  • O

    off-peak

    Off-peak, in a call center context, describes a time period with fewer calls than are handled in a busy period... (Continued)

  • Open Settlement Protocol (OSP)

    Open Settlement Protocol (OSP) is a client-server protocol that manages access control, accounting, usage data and inter-domain routing to make it easier for Internet service providers to support IP telephony.

  • Optivity Telephony Manager (OTM)

    Optivity Telephony Manager (OTM) is an application that provides single-point analysis, configuration, and management of telephony networks using a Web browser or graphical user interface (GUI).

  • ORTC (Object Real-Time Communications)

    ORTC (object real-time communications) is an open source component of WebRTC that enables mobile endpoints to talk to servers and Web browsers with real-time communications capabilities. ORTC is under development by a W3C community group that is supported by vendors including Hookflash, Google and Microsoft.

  • outbound call center

    An outbound call center is one in which call center agents make outbound calls to customers on behalf of a business or client... (Continued)

  • P

    packet loss concealment (PLC)

    Packet loss concealment (PLC) is a technology designed to minimize the practical effect of lost packets in digital communications... (Continued)

  • podcasting

    Podcasting is the preparation and distribution of audio files using RSS to the computers of subscribed users. These files may then be uploaded to digital music or multimedia players like the iPod. A podcast can be easily created from a digital audio file. The podcaster first saves the file as an MP3 and then uploads it to the Web site of a service provider. The MP3 file gets its own URL, which is inserted into an RSS XML document as an enclosure within an XML tag.

  • Premium Rate Service (PRS)

    In the U.K., Premium Rate Service (PRS) is a telephone service that provides recorded information or live conversation for callers similar to 1-900 number service in the U.S. Callers are charged a higher rate on their phone bill, which is then split between the service provider and the network operator who leases the PRS number to the provider.

  • presence leveraging

    Presence leveraging refers to any technology that supports and expands presence, the ability of a network subscriber to locate and identify any other user's computing device as soon as the other user connects to the network... (Continued)

  • 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... (Continued)

  • private branch exchange (PBX)

    A private branch exchange (PBX) is a telephone system within an enterprise that switches calls between users on local lines, while enabling all users to share a certain number of external phone lines.

  • Q

    Q signaling (QSIG)

    Q signaling (abbreviated QSIG), a protocol for Integrated Services Digital Network (ISDN) communications based on the Q.931 standard, is used for signaling between digital private branch exchanges (PBXs).

  • Q.931

    Q.931 (also called Q93 is a signaling protocol for Integrated Services Digital Network (ISDN) communications that is used in voice over IP (VoIP).

  • QoS (quality of service)

    Quality of service (QoS) refers to any technology that manages data traffic to reduce packet loss, latency and jitter on the network.

  • R

    R-value

    R-value is a number, or score, that is used to quantitatively express the subjective quality of speech in communications systems, especially digital networks that carry voice over IP (VoIP) traffic, or for which VoIP service is under consideration.

  • real-time application (RTA)

    A real-time application (RTA) is an application program that functions within a time frame that the user senses as immediate or current. The latency must be less than a defined value, usually measured in seconds... (Continued)

  • real-time communications (RTC)

    Real-time communications (RTC) is any mode of telecommunications in which all users can exchange information instantly or with negligible latency. In this context, the term 'real-time' is synonymous with 'live.'

  • real-time communications dashboard (RTCD)

    A real-time communications dashboard (RTCD) is an application designed to facilitate efficient, convenient real-time communications (RTC) in a business environment. RTC is any mode of telecommunications in which all users can exchange information instantly or with negligible latency... (Continued)

  • Real-Time Transport Control Protocol (RTCP)

    Real-Time Transport Control Protocol (RTCP) is a protocol that works with Real-Time Protocol (RTP) to monitor data delivery on large multicast networks, mainly for streaming media, telephony and video conferencing.

  • regional Bell operating company (RBOC)

    Regional Bell operating company (RBOC) is a term describing one of the U.S. regional telephone companies (or their successors) that were created as a result of the breakup of American Telephone and Telegraph Company (AT&T, known also as the Bell System or "Ma Bell") by a U.S. Federal Court consent decree on December 31, 1983. The seven original regional Bell operating companies were Ameritech, Bell Atlantic, BellSouth, NYNEX, Pacific Bell, Southwestern Bell, and US WEST. Each of these companies owned at least two Bell operating companies (Bell operating company).

  • registration, admission, and status (RAS)

    Registration, admission, and status (RAS) is a component of a network protocol that involves the addition of (or refusal to add) new authorized users, the admission of (or refusal to admit) authorized users based on available bandwidth, and the tracking of the status of all users.

  • rich presence technology (RPT)

    Rich presence is an enhanced form of presence awareness in which participants can determine if other users are online and if so, observe to a limited extent what they are doing and how they are doing it... (Continued)

  • RoundTable

    Microsoft RoundTable is a videoconference device designed to simulate in-person meetings... (Continued)

  • S

    scalable video coding (SVC)

    Scalable video coding (SVC) is an extension of the H.264 (MPEG-4 AVC) video compression standard for video encoding.

  • SDP (Session Description Protocol)

    SDP (Session Description Protocol) is a set of rules that defines how multimedia sessions can be set up to allow all end points to effectively participate in the session. In this context, a session consists of a set of communications end points along with a series of interactions among them... (Continued)

  • Session Announcement Protocol (SAP)

    Session Announcement Protocol (SAP) is a protocol used to define the format and describe the information that will be exchanged during a multicast conferencing session. 

  • Session Initiation Protocol (SIP)

    Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, modifying and terminating real-time sessions that involve video, voice, messaging and other communications applications and services between two or more endpoints on IP networks.

  • Signalling Connection Control Part (SCCP)

    Signalling Connection Control Part (SCCP) is a portion of International Telecommunication Union (ITU) recommendation Q.711, which is the routing protocol for Signalling System 7 (SS7), a set of protocols used to set up calls in telephony networks.

  • SIP trunking (Session Initiation Protocol trunking)

    Session Initiation Protocol (SIP) trunking is a service offered by a communications service provider that uses the protocol to provision voice over IP (VoIP) connectivity between an on-premises phone system and the public switched telephone network (PSTN).

  • Skinny Client Control Protocol (SCCP)

    Skinny Client Control Protocol (SCCP) is a Cisco proprietary standard for terminal control for use with voice over IP (VoIP).

  • Skype for Business

    Skype for Business, formerly known as Microsoft Lync Server, is a unified communications (UC) platform that integrates common channels of business communication and online meetings, including instant messaging (IM), presence, voice over IP (VoIP), video conferencing, file transfer, web conferencing, voicemail and email.

  • Skype protocol

    Skype protocol is a peer-to-peer Internet telephony protocol used to move encrypted voice over IP (VoIP) traffic between Skype members' computers (peers).

  • softphone (soft client telephone)

    A softphone (software telephone) is 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.

  • speech technology

    Speech technology is a type of computing technology that enables an electronic device to recognize, analyze and understand spoken word or audio.

  • SPIT (spam over Internet telephony)

    SPIT (spam over Internet telephony), sometimes known as vam (voice or VoIP spam), is unsolicited bulk messages broadcast over VoIP (Voice over Internet Protocol) to phones connected to the Internet.

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