VoIP and Asterisk Glossary

Listing of common VoIP, IP-PBX and Asterisk terms along with their definitions.

Terms & Definitions

API Application Programming Interface (API) – is a set of functions, procedures, methods or classes that an operating system, library or service provides to support requests made by computer programs.
Asterisk – Open source PBX, telephony engine, and telephony applications toolkit.
Asterisk Appliance – A stand-alone embedded Asterisk-based PBX
Asterisk Boards Asterisk compatible telephony boards
Asterisk BRI Asterisk system compatible with BRI
Asterisk Cards Telephony – cards used to integrate existing analogue telephone handsets and analogue lines into the Asterisk PBX.
Asterisk Distribution – Method to access Asterisk products.
Asterisk FXO – Asterisk compatible Foreign Exchange Office.
Asterisk FXS – Asterisk compatible Foreign Exchange Services.
Asterisk Hardware – Computer components designed for use with Asterisk
Asterisk IP-PBX – An open source communications platform based on IP (Internet Protocol) PBX (Private branch exchange) as a business telephone system.
Asterisk ISDN – Asterisk compatible Integrated Services Digital Network (ISDN). This telephone system network integrates speech and data on the same lines while adding features that were not available in the classic telephone system.
Asterisk PBX – An open source communications platform based on PBX (Private branch exchange) as a business telephone system.
Asterisk Server – Asterisk’s platform upon which equipment providers can build a network infrastructure. The server supports a mix of traditional and VoIP telephony services, enabling new telephone systems to be built, or slowly convert existing systems to new technologies.
Asterisk Solutions – Products and services designed for use with Asterisk.
Asterisk System – See Asterisk
Asterisk Telephony – See Asterisk
Asterisk VoIP – Open source telephony platform and tool kit with Voice Over Internet Protocol (VoIP) capabilities.
Astribank – A USB channel bank especially designed for Asterisk Open Source PBX systems.
Audiocodes – Manufacturer of VoIP (Voice Over IP) technologies and products.
BRI – Basic Rate Interface (BRI) is an Integrated Services Digital Network (ISDN) channel consisting of two 64 kbit/s “bearer” channels (B channels) and one 16 kbit/s “delta” channel (D channel). The B channels are for voice or user data. The D channels are for control and signaling and/or networking. The two B channels can be bonded together.
BRI Channel Bank – A channel bank with BRI ports.
BRI ISDN – ISDN with BRI ports.
Call Manager – A system which organizes the shared lines for incoming and outgoing telephone calls.
Channel Bank – A device that performs multiplexing or demultiplexing of a group of communications channels into one channel of higher bandwidth or higher digital bit rate.
CLEC – Competitive Local Exchange Carriers. A telecommunications carrier/service provider that competes with other, already established carriers.
Cyber-Attack – When referencing IP-PBX, refers to unauthorized use of the IP phone network, typically for purposes of toll fraud.
DAHDI – Digium Asterisk Hardware Device Interface. See Zaptel
Demultiplexing – The reverse of multiplexing.
Digium – The creator and primary developer of Asterisk, the industry’s first open source telephony platform. Asterisk is the basis for all Xorcom products.
Elastics – Common misspelling for Elastix.
Elastix – An appliance software that integrates tools available for Asterisk based PBXs into a single interface.
Elastix Appliance – See Elastix above.
Embedded Asterisk – Platforms created with Asterisk built-in.
EPABX – Electronic Private Automatic Branch Exchange. See PBX
FXO Foreign Exchange Office (FXO) – An FXO is any device that sends and receives voice frequency signals, accepts ringing signals, can “on-hook” and “off-hook”. FXO interfaces are also available for computers and networking equipment.
FXO Card – Card with an FXO interface.
FXS Foreign Exchange Station (FXS) – This is a telephone interface which generates ringing voltage, provides battery power, sends a dialtone, understands when the phone goes on-hook or off-hook, and sends and receives voice signals. An example of this would be the phone jack, unless plugged in, calls can’t be made.
FXS Card – Card with an FXS interface.
High Availability – A characteristic of a system, in this case IP-PBX, which describes the duration (length of time) for which the system is operational. High availability is specifically desirable in businesses which depend on communication for their livelihood.
iPBX , IPBX , IP-PBX IP (Internet Protocol) PBX (Private branch exchange) – business telephone system designed to deliver voice over a data network and interoperate with the normal Public Switched Telephone Network (PSTN).
ISDN – Integrated Services Digital Network (ISDN). This is a telephone system network which integrates speech and data on the same lines. Additional features advance this system as compared to the traditional telephone system.
Multiplexing – The process where several analog message signals or digital data streams merge into one signal over a shared medium.
PABX – Private Automatic Branch Exchange. See PBX
PBX – Private branch exchange (PBX) is a telephone exchange system used by business offices. Users of the PBX share a certain number of external lines for making telephone calls as opposed to connecting an external telephone line to every telephone in the organization.
PCI – Card The Peripheral Component Interconnect (PCI) is used to attach peripheral devices to a computer motherboard.
PRI – Primary Rate Interface (PRI) is an access interface to the ISDN.
R2 – R2 is an access interface to the ISDN, primarily popular in Latin America.
SBC – Session Border Controller. Hardware or software usually located between a public network (“untrusted”) and a service provider network in the enterprise (“trusted”). Historically, SBC was used to solve SIP NAT-related problems, but nowadays SBC governs voice traffic on the SIP network.
SIP – Session Initiation Protocol is a communications protocol for signaling and controlling multimedia communication sessions. SIP is used widely in Internet telephony for voice and video calls over IP networks.
SMB – Small and Medium-sized Business(es). Also known as SME – Small and Medium-sized Enterprise(s).
SMP – Symmetric multiprocessing. In this computer-architecture two or more identical processors connect to one shared main memory.
Soft Phone – A software program used for making telephone calls over the Internet via computer. The program is designed to function like a traditional phone.
SOHO – Small Office / Home Office
VoIP – Voice Over Internet Protocol (Voip) is used to transmit audio/voice through the Internet or other packet-switched networks.
Zaptel – An open computer telephony hardware driver API. The name has recently been changed to DAHDI.