Unified Communications Dictionary

Understanding the phrases and language used by the communications industry can be overwhelming and challenging to follow. So, we decided to put together a collection of definitions to help you navigate the content out there and discover what it means!

0-9     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


1080p resolution:

High-definition video modes characterized by 1080 horizontal lines of vertical resolution

3G / 4G /5G :

Mobile communications networks


Address Resolution :

A method of identifying an IP address of a called endpoint regarding the network.

Address Translation :

The ability of a Gatekeeper to translate an alias address, name or e-mail address, to a transport address.

Algorithm :

Any step-by-step problem-solving procedure.

Application Level Gateway :

Application Level Gateways (ALGs) work as communicators connecting two networks.


Admissions Reject message – Sent by the Gatekeeper to the calling endpoint, rejecting the ARQ.


Admissions ReQuest message – sent by an endpoint placing a call /receiving a call requesting bandwidth & permission to continue setup.


Asynchronous Transfer Mode – A high-speed controlled-delay packet switching and transmission system are integrating multiple data types (voice, video & data).

Authentication :

Verifying the identity of a user attempting to log on to a system, or the sender of a communication.

A/V :


A/V Integration :

A/V Integration service includes the necessary steps essential in creating a tailored visual communication solution for our customers, clients, and partner organizations with an emphasis on proven, reliable technology. Starting with proven video and audio technology, we leverage simple, intuitive controls providing our customers with functional and productive visual communications environments.


B Channel :

Bearer channel – ISDN communications – B channel transmits data or voice at 64 or 56 Kbps.

Bandwith :

The capability of a communications channel.

Bonding :

Bandwidth ON Demand. Increasing the bandwidth of a call by linking two or more B channels of an ISDN line.

Border controllers :

A session border controller (SBC) is a device regularly deployed in Voice over Internet Protocol (VoIP) networks to exert control over the signalling and usually also the media streams involved in setting up, conducting, and tearing down telephone calls or other interactive media communications.

bps :

Bits per second – The unit of measurement of the speed of data transmission.

Bps (or BPS) :

Bytes (8-bit) bytes per second. A unit of measurement of the speed of data transmission.


Basic Rate Interface – ISDN subscriber interface is supporting two bearer B channels and one data D channel.

Bridge :

A connection between three or more conference sites.

Broadband :

A method of sending substantial amounts of data, voice and video than telephony networks allow.

Broadcast :

The transmission of data to everybody on a network.


Call Authorization :

Acceptance or rejection of calls from one H.323 terminal.

Call Control :

Also called Call Processing. The signalling associated with setting up, monitoring, transferring and disconnecting a call.

Cascaded MCU :

The MCU allows you to connect two or more conferences resulting in a larger conference with additional participants. Cascading creates a shared environment helping to reduce the strain on a network.


Common Intermediate Format

Circuit Switching :

A temporary but dedicated connection between two stations regardless of the number of devices switching through data which is routed.

Cisco Proxy :

The Cisco H.323 Proxy is a device that acts as a Gateway and relays H.323 data between H.323 zones.

The Cloud :

In cloud computing, the word cloud (also phrased as “the cloud“) is used as a metaphor for “the Internet,” so the phrase cloud computing means “a type of Internet-based computing,” with different services — such as servers, storage and applications. The cloud is a virtual means of accessing the internet, collaborating with colleagues and storing data via remote locations, without direct ties to physical infrastructure. 

Cloud Collaboration :

Cloud collaboration is a networked connection of people across the planet, connecting over voice and video from many devices

Cloud Infrastructure:

The hardware and software components — such as servers, storage, a network and virtualization software — that are needed to support the computing requirements of a cloud computing model

Cloud Video :

Video hosted via the Cloud.

Collaboration infrastructure :

Collaboration infrastructure usually involves: endpoints, video services (recording, streaming, conferencing), video network services (call control, gateways), management, network (router, switch, firewall)


COder / DECoder. Hardware/ software that converts sound, speech or video signals from analogue to digital code and vice versa.

Compression :

A technique for reducing the bandwidth or bit rate required, so it occupies less space on a transmission.

Conference scheduling and production :

Conference scheduling and production means: Scheduling and confirming your conferences, Event pretesting to ensure readiness, A dedicated technician to welcome participants and ensure all parties are connected to the meeting, Live assistance and event management, Audio add-on and meeting recording, Connection/Disconnection of conferences, Conferencing reporting


D Channel :

Data signalling channel of an ISDN line.

Default Extension :

Any endpoint on the network that has been defined an alternative destination for incoming calls routed by a Gateway

Delay :

The time taken for a signal to pass through a video conference from sending to receiving.


Data Encryption Standard.

Desktop Video Conferencing :

Video conferencing on a personal computer.


Dynamic Host Configuration Protocol.


Direct Inward Dialing.

Direct Mode :

Routing of the Call Setup channel (Q.931) and the Control channel (H.245) to form a direct connection between two endpoints without Gatekeeper intervention.

Distance learning :

A method of studying in which lectures are broadcast or lessons are conducted by correspondence, without the student needing to attend a school or college.


Domain Name Server.


Echo-Cancellation :

Eliminating the acoustic echo effect on video conference calls.

End user :

The ultimate consumer of a finished product.


A term that suggests that the supplier of an application program or system will provide all the hardware and/or software components and resources to meet the customer’s requirement and no other supplier need be involved.

Endpoint :

Endpoints are devices or nodes connected to a network, accepting communication back and forth.

Endpoint management :

The approach to securing and controlling desktop computers, laptops, smartphones and tablets in a connected, cohesive manner from a single console.

Ethernet :

A LAN physical and data link protocol running over the lowest two layers of the OSI Reference Model at speeds of up to 10 or 100Mbps.


Firewall :

A barrier device placed between two separate networks that serves a network security purpose.

Flow Control :

Hardware/ Software/ Procedure for controlling the transfer of IP packets between two points on a network.

Frame Rate :

The rate at which individual video frames run in a sequence.

Fully managed video estate :

An end-to-end managed service that enables organizations to enjoy the full benefits of their video communications technology, with increased reliability, flexibility and cost savings.


Gatekeepers :

Gatekeeping is when information is filtered for dissemination, whether for publication, broadcasting, the Internet, or some other mode of communication.

Gatekeeper Zone :

A group of endpoints together with their Gatekeeper constitute a zone.

Gateway :

A Gateway is a network object which implements a bridge between networks.


Gatekeeper Confirm Message.

Global support :

Collaborative technology experts help with end-user assistance, warranty & maintenance for your hardware, and training material. Pinnaca’s global support capability enables us to help whenever, wherever you need us.

Globally-hosted locations :

Cloud infrastructure provided from multiple different points around the globe.


H.225.0 :

H.225.0 specifies the procedures and messages applicable to Gatekeepers, including the RAS protocol for Registration, Admission and Status.

H.235 Security :

H.235 Security ensures the authentication of each endpoint and the integrity of messages. The basis of the security process is the shared secret between the endpoint and the Gatekeeper.

H.239 :

ITU-T standard for role management and additional media channels for H.300 – series terminals.

H.245 :

The ITU-T standard used for the Control Protocol for Multimedia Communication.

H.248 :

The ITU-T standard for signalling and control between circuit-switched PSTNs and VoIP networks.

H.264 :

The ITU-T standard for compression that allows higher quality calls to pass over a lower bandwidth for advanced video coding in generic audiovisual services.

H.261 :

H.261 supports CIF and QCIF resolutions.

H.263 :

H.263 offers improved compression over H.261 and transmits video with QCIF support.

H.320 :

The ITU-T standard for video conferencing over digital networks such as ISDN.

H.323 :

A binary-based standard developed by the International Telecommunication Union to support rich-media communications over IP networks that was initially focused on video conferencing, but now includes audio and video conferencing.

H.324 :

The ITU-T standard for video conferencing over analogue telephone lines using modems.

H.350 :

ITU-T standard for directory services architecture for multimedia conferencing.

HIPAA compliance

Companies that deal with protected health information (PHI) must have physical, network, and process security measures in place and follow them to ensure HIPAA Compliance.


Infrastructure management :

A service that consists of designing, managing and supporting video collaboration infrastructure.

Instant Messaging (IM) :

A message service that permits you to create a private chat with another individual to talk in real time over the Internet.

Interoperability :

The ability of computer systems or software to exchange and make use of information. For example, the ability to communicate with Skype from legacy video Conferencing Hardware.

Intranet :

A local or restricted communications network, especially a private network created using World Wide Web software.

IP Address :

The unique address of a computer attached to a TCP/IP network.

IP Network :

A network that uses the TCP/IP protocol.

IP Telephony :

A set of technologies that enables voice, data and video collaboration over existing IP-based LANs, WANs and the Internet.


Information Request Message – A message in which the Gatekeeper asks the endpoint for its current status.


Information Request Response Message – A message that the Gatekeeper sends to the calling endpoint, rejecting the IRQ.


Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.

ISO27001 :

The specification for an information security management system (ISMS). An ISMS is a framework of policies and procedures that includes all legal, physical and technical controls involved in an organisation’s information risk management processes.


Interactive Voice Response is a two-stage incoming call routing method supported by the Gateway. It enables DID to a LAN terminal, even when the ISDN lines do not have multiple numbers allowing direct dialling to an endpoint.


Jitter :

The result of a change in latency or the tendency towards lack of synchronisation caused by mechanical or electrical changes.

Jitter Buffer :

A portion of memory allocated explicitly to storing IP packets awaiting transmission, or to saving received IP packets.


kbps :

Kilobits per second. One thousand bits per second.



Local Area Network. The internal communications network of an organisation.

LAN/WAN Connectivity :

Layer protocols to support services that make a remote access device an active link between LANs and WANs.

Latency :

A measure of accumulated waiting time or delay, describing the length of time required for information to pass through a network.


Managed Services :

Managed services means bringing in experts to manage, produce and/or support your collaborative technology.

Mbps :

Megabits per second. One million bits per second.


Multipoint Control Unit – A device that is used to moderate a videoconference of three or more end points, an end point being one or more users in a single location.

MPEG-4 :

Moving Pictures Experts Group. MPEG-4 provides the standardised technological elements for the integration of interactive graphics applications and interactive multimedia.

MPLS interconnects :

MPLS Inter-Carrier Interconnect (MPLS-ICI) Technical Specification IP/MPLSForum 19.0.0. Page 1. MPLS Inter-Carrier Interconnect.

Multipoint :

Communication configuration in which several terminals or stations are connected. Contrast with point-to-point.

Multipoint Video Conference :

Video conference with more than two sites. The sites must connect via a video bridge.

Multi-Unicast :

Transmission of duplicate data streams, one to each user. In multi-unicast, multiple users request the same data from the same server at the same time. Contrast with IP multicast, unicast.



Network Address Translation – NAT devices translate IP addresses so that users on a private network can see the public network, but public network users cannot see the private network users.

Network :

A group of stations (computers, telephones, or other devices) connected by communications infrastructures for exchanging information.


Network Specific Facility – The Network Specific Facility Information Element (NSFIE) feature enables system administrators to coordinate their network and service requirements with Service Providers.


Operator (concierge) services :

There are a number of operator service options available including scheduled call launches; scheduled meet and greet, and scheduled operator-attended video conferences.

Operator-attended Service :

An Operator-Attended service consists of launching all video and audio participants into an MCU or  Virtual Room, Verifying audio and video quality from each participant, ensuring the correct screen layout is on screen, establishing content is working, securing the room and muting participants.


Packet :

A block of data used for transmission in packet-switched systems.

Packet Loss :

The discarding of data packets in a network when a device is overloaded and cannot accept incoming data at a given moment.

Packet Re-Ordering :

Ensuring that all packets reach their destination in the correct sequential order.

Packet Switching :

A networking technology that breaks up a message into smaller packets for transmission and switches them to their required destination.

Point-To-Point :

Communication configuration in which communication is between two stations only


Point of Presence – The point at which a line from a long distance carrier connects to the line of the local telephone company, or to the user if the local company is not involved.

Port :

A pathway into and out of a computer or a network device, such as a switch or router.


Plain Old Telephone Service.

Professional Services :

Professional services means bringing in experts to assist in all areas of designing, developing and supporting your collaborative technology.


Coming soon

Are we missing something?  Request a missing definition at the bottom of the page.



Resource Available Indication / Resource available Confirmation – A function that manages load balancing on the network.


A protocol for Registration, Admission and Status. In an H.323 audio or video system, the RAS is a control channel over which H.225.0 signalling messages are sent.


Registration ConFirm message. A RAS message that a Gatekeeper sends to the calling endpoint accepting the RRQ.

Real-Time :

The processing of information that returns a result so rapidly that the interaction appears to be instantaneous. Video conferencing is an example of a real-time application.

Redundancy :

See Gateway Redundancy.


Return on Investment.



Session Initiation Protocol (SIP) is a communications protocol for signaling and controlling multimedia communication sessions in applications of Internet telephony for voice and video calls.

Slave :

The side in communications which response to session commands. The ‘master’ is the other side that initiates and controls the session.


Simple Network Management Protocol – A widely used network monitoring and control protocol.


Sub Quarter Common Intermediate Format. A video format with dimensions of 88 x 72 pixels.

Sub-Addressing :

Sub-addressing is a one-stage DID dialling mechanism in which a phone sends two numbers. One number is for routing on the circuit-switched network.

Sub-Conference :

The current version of the Radvision MCU allows the creation of audio sub-conferences to which selected participants in an existing conference can be temporarily diverted.

Subnet :

A subnet is a portion of an IP network defined by a subnet mask. Devices on the same subnet have the same subnet mask.


Telehealth :

The remote diagnosis and treatment of patients by means of telecommunications technology.

Telemedicine :

The remote diagnosis and treatment of patients by means of telecommunications technology.

Telecommunication :

The transmission of messages, words, writings, images and sounds by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology.

Transcoding :

Auto transcoding is the conversion of audio transmissions to achieve different audio quality levels at reduced bandwidth levels.



Unregistration ConFirm Message – A message that a Gatekeeper or an endpoint sends accepting the URQ.

Unregistered Endpoint

An endpoint that is not online/ registered with a Gatekeeper.


The address of a World Wide Web page.

User adoption :

The change between an old system and a target system. Adoption happens in several phases, each phase the system is a little closer to being fully adopted by the company.


Vendor agnostic :

We work with multiple technology vendors, so you get the right solution for your needs.

Video Bit Rate :

The speed at which bits are transmitted.

Video Bridge :

A computerised switching system that allows multipoint video conferencing.

Video Collaboration :

Video collaboration is a live, visual connection between two or more people residing in separate locations for the purpose of communication. At its most sophisticated, it provides transmission of full-motion video images and high-quality audio between multiple locations.

Video Conferencing :

Telecommunication in the form of a videoconference.

Video Conferencing as a Service (VCaaS) :

A global, always-available virtual meeting space used for collaboration with customers, colleagues, partners, suppliers, and more.

Video Infrastructure Service :

A global, always-available, video infrastructure deployed in NA, EMEA and AsiaPac that includes most vendor technologies such as Cisco, Polycom and next-generation platforms from Acano, PEXIP and Vidyo.

Video network operations center (VNOC) :

VNOC is staffed by teams of highly knowledgeable professionals responsible for providing customers with a best in class service and support capability for video communications and collaboration, 24x7x365.

Virtual expert :

Virtual Expert is a comprehensive set of consulting services that are designed to address the full lifecycle of an organization’s visual communications and collaboration strategy.

Virtual room :

A video meeting space located in the cloud.


Voice over IP



Wide Area Network – A network spread over a wide area.

Webcasting :

To broadcast (an event) on the Internet.


Coming soon

Are we missing something?  Request a missing definition at the bottom of the page.


Coming soon

Are we missing something?  Request a missing definition at the bottom of the page.


Coming soon

Are we missing something?  Request a missing definition at the bottom of the page.