What Is Voice Over Internet Protocol?

What is Voice over Internet Protocol

Voice over Internet Protocol, voice-over-IP, or simply VoIP, is a form of Internet telephony technology that manages the delivery of voice communications over the Internet or intranet. Voice-over-IP technology converts voice to digital data and then transmits it in discrete packets over the Internet, as opposed to using traditional circuit-committed protocols, as is the case with public switched telephone network (PSTN) service. One of the most recognized benefits of VoIP and IP telephone is the ability to reduce (or eliminate) the costly toll charges billed by the local phone company.

VoIP is a derivative of the VoIP forum, a joint effort of many leading hardware providers to market the use of ITU-T H.323 (the standard of sending audio and video over the Internet).

Besides IP, Voice-over-IP harnesses the real-time protocol, or RTP, to make certain that digital packets are delivered quickly and without compromise. For most, it is hard to guarantee Quality of Service (QoS) when using public networks; however, it is possible to mitigate this with services sent across private networks, like those managed by a provider of Internet telephony services, also called VoIP solutions providers or ITSP.

Glossary of VoIP terms

Asynchronous transfer mode (ATM)

A switching technology that organizes digital data and transmits it over a digital signal

Audio menu

A recorded menu, audio choice menus are common in auto-attendants, IVRs and fax-on-demand systems. These types of audible menus prompt caller input.

Audio response unit (ARU)

A digital telephony system that incorporates voice storage and forward technology. ARUs play messages based on the input received from callers.

Conference bridge

A device used to connect several parties over the telephone. There are two types of conference bridges, standalone conference bridges and conference bridges built into PBXs.

Differentiated services

The protocol for controlling and specifying traffic on a network by class so that pre-specified traffic gets priority. IE: voice traffic may be prioritized over other traffic.

Digital subscriber line (DSL)

A digital switch that relies on existing copper pairs to connect customer equipment to central office.


The 2.048 Mbps ITU standard for Europe’s 30 channel digital telephone service. Visit the ITU’s website for more information.

Frame relay

A packet switching method that utilizes available bandwidth only when it is required. This is typically efficient enough to transmit voice communications.

Full duplex

refers to the ability for both ends of a communication to send and receive information without compromising quality.

Interactive Voice Response (IVR)

IVR is the application wherein computer information can be accessed over the telephone and utilizes the caller’s touch-tones or voice commands. IE: entering banking information on telebanking.

Internet Protocol

Protocol used to send data from one computer (or phone) to another over the Internet.

Internet Engineering Task Force

(IETF)Body responsible for defining standard Internet operating protocols Visit the IETF.

IP Telephony

used to refer to the technology that leverages IP packet-switched connections to exchange voice, fax and other communications that would traditionally have been carried out over the local telephone networks.


Problems with packet arrival time.


local area network.


The amount of time it takes for data packets to travel from one area to another.

Quality of Service (QoS)

the concept of measuring transmission rates, error rates and other characteristics.

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