Communication Tower


ATA - Analog Telephone Adaptor

An ATA is a piece of hardware that converts audio, data and video signals into Internet Protocol (IP) packets that can then be transferred over the internet. It can be used to connect a standard telephone to a high bandwidth line to make voice calls using Voice over Internet Protocol (VoIP). ATAs also process the required connection and input conversions needed to manage the call. Multi-format ATAs, which handle audio, data and video, are also known as Integrated Access Devices (IADs) and Multimedia Terminal Adaptors (MTAs).

Audio Encoding

Audio codecs encode or decode digital audio data packets, and can be a piece of software or a hardware device. Session Initiation Protocol (SIP) is codec-agnostic and accepts all audio codecs the International Telecommunication Union (ITU) connects with the H.323 recommended standard.


Bandwidth says how much data can be transferred in a given period of time, i.e. a data transfer rate, and is usually measured in bits per second (Bps). Analog devices’ bandwidth is measured in Hertz (Hz), or cycles per second.

Broadband Telephony

A communications protocol for transmitting telephone calls over a broadband internet network. Other terms commonly associated with Broadband Telephony are IP telephony, Internet telephony, and broadband phone service.


A codec converts the data stream of a piece of software or a hardware device, in order for it to be sent, received, used, stored or encrypted. They are especially useful for video streaming and video conferencing. Codecs are so called because they both compress or decompress and encode or decode data packets.

Data Network

Data networks allow computers, acting as network access points known as nodes, to send and receive data packets across network connections, and for multiple users to access, use, store or encrypt data. Data networks can vary greatly in size and complexity, but generally use system controls, data switches, and network links or data connections.


Enhanced 911, or E911 for short, is a voice communication system dedicated to connecting mobile and internet phone users to the emergency services.


Ethernet refers to industry standard IEEE 802.3 and is the internet-like system behind a Local Area Network (LAN), transmitting data packets according to various protocols within a private network. Ethernet transmission rates are measured in bits per second (Bps), and speeds are moving from Mbps to Gbps using fibre optic technology.

Gateway in VOIP Systems

Voice over Internet Protocol (VoIP) systems use gateways to convert voice calls and fax communications received from a Public Switched Telephone Network (PSTN), so they can be sent as digital packets over an Internet Protocol (IP) network.

Internet Telephony / IP Telephony / VoIP Telephony

Used interchangeably, Internet Telephony, IP Telephony and Voice Over Internet Protocol (VoIP) all refer to voice communications sent and received over the internet. Communications can be transmitted PC-to-PC directly over the internet, and from phone-to-PC, PC-to-phone and phone-to-phone via the internet, using a gateway to go between analog and digital networks. All-digital PC-to-PC communications are the closest to providing real time communications.

Internet Phone / IP Phone / SIP Phone / VoIP Phone HOME / GLOSSARY ITEM / INTERNET

Various names are used for any hardware device or piece of software that allows packets of voice data to pass over the internet between users, and enables voice calls and communications. H.323 or Session Initiation Protocol (SIP) can guide the data packets; gateways convert audio data and codecs convert video data. IP phones that bypass any Public Switched Telephone Network (PSTN) do not require gateways. Voice over Internet Protocol (VoIP) telephony offers low to zero-cost call rates.

Internet Phone / IP Phone / SIP Phone / VoIP Phone

Various names are used for any hardware device or piece of software that allows packets of voice data to pass over the internet between users, and enables voice calls and communications. H.323 or Session Initiation Protocol (SIP) can guide the data packets; gateways convert audio data and codecs convert video data. IP phones that bypass any Public Switched Telephone Network (PSTN) do not require gateways. Voice over Internet Protocol (VoIP) telephony offers low to zero-cost call rates.

IP – Internet Protocol

Internet Protocol (IP) is a communications system that uses formats and rules to route data packets or datagrams from one computer to another over the internet.

IP Address

An Internet Protocol (IP) address is a fixed or dynamic number ranging from to associated with every internet-enabled device. IP numbers are an essential piece of information for connecting different devices over the internet, for voice and data communications.

IPBX / IP-PBX – Internet Protocol Private Branch Exchange HOME / GLOSSARY ITEM / IPBX / IP-PBX – INTERNET PROTOC

An Internet Protocol Private Branch Exchange (IPBX) is a telephone exchange, local to a building or area, whose calls are managed and processed within an Internet Protocol (IP) network, such as a Local Area Network (LAN). Access to and from both internal IPBX systems, and external telephone networks, including the Public Switched Telephone Network (PSTN), is controlled by a network device referred to as a gateway (see above). IPBX systems offer call transfer, PC phone integration, speed dialing, and voicemail, as well as privacy and control to its owners. H.323, MEGACO (an upgrade to MGCP), and SIP are all examples of IPBX standards.

ISP – Internet Service Provider

Internet Service Providers (ISPs) are companies that offer internet access for residential and/or commercial customers, with optional services such as email accounts, fax capability, audio and video communications and site hosting available. Generally, agreements are subscription-based, i.e. a monthly or annual fee, and users pay more for higher bandwidth and faster internet. Local ISPs connect to regional ISPs, which in turn provide access to the internet backbone and to peer-to-peer Metropolitan Area Exchanges (MAEs) or Network Access Points (NAPs). Routers, servers and modems are essential components of the internet infrastructure at each level.

ITSP – Internet Telephony Service Provider

Internet Telephony Service Providers (ITSPs) allow users to use their existing internet connection to operate an internet, IP, SIP or VoIP phone. By combining voice and data on the same digital infrastructure, ITSPs can offer Unified Communications (UC) across multiple devices. Gateways can convert voice calls and fax communications from a Public Switched Telephone Network (PSTN) for phone-to-PC calls.

LAN – Local Area Network

Local Area Networks (LANs) connect computers to each other within an isolated environment, such as an office, school or home, and use either ethernet or token ring architecture to transmit data within the private network. LANs offer very fast communication speeds, usually via coaxial, fiber optic or twisted-pair cables.


Although data communications can be measured in milliseconds and nanoseconds, there is always some delay between a data request and data transfer result. This delay is called latency and the closer transmission speeds come to zero, the better the latency between communicating devices is considered to be. Technically, the speed of light (3×108 m/s) rather than zero represents perfect latency.

P2P – Peer-to-Peer

Peer-to-Peer (P2P) refers to the shared use of files, power, bandwidth, etc., by two or more computers. A P2P network makes optimum use of all resources available across connected computers (acting as nodes) with each computer having network capabilities and responsibilities. This compares to client-server architecture, where certain machines are designated to serve other machines on the network.

PBX / PABX – Private Branch Exchange / Private Automatic Branch Exchange

A Private Branch Exchange (PBX) or Private Automatic Branch Exchange (PABX) systems replaces the traditional telephony switchboard, with a private telephone network exchange. PBX phone systems offer additional features such as caller greetings, conference calling, call holding or extension routing.

POP – Point of Presence

A Point of Presence (POP) is a carrier facility, found within digital communications infrastructure, which lets devices or networks connect to the internet. Internet Service Providers (ISPs) usually manage several POPs, often distinguishing between user groups and providing a direct connection for business customers.

POP – Post Office Protocol

Post Office Protocol (POP) is an application-layer internet standard for receiving email. POP3, a client-server protocol, is the most recent version of the POP standard, and lets a server hold any email until a client requests access.

Proxy Server

A proxy server is an intermediary device used to connect, for example, all computers on a Local Area Network (LAN) to the internet. The same LAN can host the proxy server, or it can be located on an external network. Proxy servers generally treat one device as client, the other as a server, depending on data requests and resources.

POTS Line - Plain Old Telephone Service

Short for plain old telephone service, which refers to the standard telephone service that most homes use. In contrast, telephone services based on high-speed, digital communications lines, such as ISDN and FDDI, are not POTS. The main distinctions between POTS and non-POTS services are speed and bandwidth.

PSTN – Public Switched Telephone Network

​The Public Switched Telephone Network (PSTN) is a collection of all the world’s telephone carriers, both private and public, and including all local, long-distance and international networks.

Service Provider

Service providers offer services for payment, on an ad-hoc or ongoing basis. In computing, this can be a business that hosts network or storage servers. Internet and Internet Telephony Service Providers (ISPs and ITSPs) respectively offer connection to the internet and voice communications.

SIP – Session Initiation Protocol

Session Initiation Protocol (SIP) is an industry standard application-layer protocol that can initiate, manage and terminate Peer-to-Peer (P2P) communications and multimedia, including voice, video, email and instant messaging. SIP is similar to H.323 packet protocol, and originates in RFC 2543 of the Internet Engineering Task Force (IETF). SIP is increasingly being used in telephony, online gaming, and the growing virtual reality industry.

SIP Phone

A SIP phone uses Session Initiation Protocol (SIP) to initiate, manage and terminate voice communications sent and received as data packets via the internet. As a Voice over Internet Protocol (VoIP) solution, SIP phone users can often call other SIP, IP, internet and VoIP users for free, and call at low rates to landline and mobile phone numbers on the Public Switched Telephone Network (PSTN).

SIP Trunking

SIP Trunking is a Voice over IP phone solution that uses a trunk to connect an IP-enabled PBX or VoIP Gateway to the internet. SIP Trunking uses cloud-based technology to take advantage of shared lines, such as a company’s existing internet connection, to combine voice and data onto one network.

Soft Switch

A soft switch is the software equivalent of a physical telephone switchboard. Internet-based telephony and a growing number of traditional telecommunication networks use soft switches to manage the connection of phone calls.


A softphone is a piece of software for desktop, laptop or tablet computers that provides a functional Voice over Internet Protocol (VoIP) telephone service. Softphones receive inputs from a microphone and outputs through the computer’s speakers or a set of headphones. Voice communications are sent and received as data packets over the internet.


Telephony can refer to the use, technology or provision of voice communications between two or more people some distance from each other. All telephony relies on the conversion of audio inputs into a form that is more suitable to be sent long distance across a particular medium, be it copper wire or fiber optics, and the subsequent conversion to an audio output at the destination.

Termination - Call Termination

Call termination, also known as voice termination, refers to the routing of telephone calls from one telephone company, also known as a carrier or provider, to another. The terminating point is the called party or end point. The originating point is the calling party who initiates the call.


A communications circuit that interconnects switches. As such, multiple users and multiple transmissions can share a trunk on a pooled basis, with contention for trunk access managed by an intelligent switching device. There are many types of trunks. Tie trunks connect Private Branch Exchange (PBX) switches in a private network, Central Office Exchange (COE) trunks connect PBXs to telephone company central office exchange switches, and interoffice trunks interconnect central office exchange switches. Trunks traditionally are directional in nature, with the options being one-way outgoing (originating), one-way incoming (terminating), or two-way (combination).

Virtual Phone Number

An additional phone number assigned to an existing phone line in order to save a caller long distance fees. For example, a virtual number with a Brazil country code can be assigned to a phone line in Portugal or to a phone line in most cities in the world. The caller pays no long distance charges and thinks the party being called is local.

VoIP – Voice over Internet Protocol

Voice over Internet Protocol (VoIP) refers to software or hardware that use the internet or a private Internet Protocol (IP) network in some way for voice communications. Analog signals, such as from a traditional telephone, need to be converted using a gateway. VoIP systems process digital signals as data packets, using routing information to identify the destination device, which then decodes these data packets into audible communication.


A Voice over Internet Protocol (VoIP) gateway is used to compress, packetize, route, signal and decompress analog voice and fax communications from Public Switched Telephone Networks (PSTNs) into digital form that can be sent over a public or private Internet Protocol (IP) data network.

VoIP PBX – Voice over Internet Protocol Private Branch Exchange

A Voice over Internet Protocol Private Branch Exchange (VoIP PBX) is a telephony switching system for internal calls that use Internet Protocol (IP), which also offers a number of traditional phone lines to be shared by users on the private network. 

Web Server

A web server is a computer system that stores and processes web page data, and which responds to client requests (i.e. inputs of the web page user) using Hypertext Transfer Protocol (HTTP). The World Wide Web relies on a vast network of servers to collect and transmit information.

Wi-Fi Hotspot

A Wi-Fi hotspot maintains a Wireless Local Area Network (WLAN) that permitted users can connect wireless devices to for internet access. Wi-Fi hotspots are becoming more common in public, retail, hospitality and commercial spaces, allowing devices without mobile internet to get online, while saving data minutes for 3G and 4G mobile, smartphone and tablet users.

Wi-Fi Phone

Wi-Fi phones can provide voice and data communications over the internet whenever a wireless signal is available. Residential customers with an Internet Service Provider (ISP) can use a Wi-Fi phone as a house phone, and also as a mobile phone usable at the office or at a Wi-Fi hotspot. Wi-Fi phones offer the advantages of free or affordable call rates, and no mobile subscription or bills.

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