OfficeVoIPSolutions' VoIP Dictionary and Guide to Common Telecom Terms

Here's a list of the more common IP telephony acronyms and telecom terms we think you should know when researching and shopping for modern IP PBXs and other IP-based communication systems.

Far from an exhaustive list, but we don't want to make you a "gear head," we just want you to be able to talk the talk.

And if you think we've forgotten an obvious entry, let us know via our Contact Us form!

100Base-T = same as above, allowing for 100MB of bandwidth availability.

802.1p - an IEEE standard for providing QoS (Quality of Service) using three bits to allow switches to reorder packets based on priority.

802.1q - an IEEE standard for providing virtual LAN (VLAN) identification and QoS levels. Three bits are used to allow eight priority levels, and 12 bits are used to identify up to 4,096 VLANs.

ACD - Automated Call Distribution = the ability of a phone system to receive inbound calls and distribute them to other phone extensions and call queues without the need for a human operator.

ANI - Automatic Number Identification = phone function that automatically transmits the billing number of the incoming call (Caller ID)

Asterisk = an open source PBX software, based on Linux, originated by the founder of the company Digium. Asterisk is to PBXs as Linux is to computer operation systems. Thanks to Asterisk, anyone can download the software (for free), install it on their own PC, connect their own IP phones, and voila, you have yourself your own home-grown phone system! Before you get too eager, know that it's NOT easy to build your own Asterisk phone system - you really need to be a Linux technician!

ATA - Analog Terminal Adapter = a device that converts an analog voice signal into IP (most common in residential VoIP services).

BCS - Business Communications System = an unofficial acronym in reference to the general technology, often integrated from various vendors, used by SMBs and enterprises in building their corporate voice and data communications infrastructure.

BLF - Busy Lamp Field = the array of lights/LEDS found on office phones that alert the user to which extensions/lines are on active calls.

BLI - Busy Lamp Indicator = the LED light on phones that shows a certain line is in use.

CDR - Call Detail Records = the statistical call data for inbound, outbound, interoffice, and voicemail calls for all phones on a system (time, date, length, caller number, recipient number, etc.)

CLEC - Competitive Local Exchange Carrier = before the Telecommunications Act of 1996, local phone companies (i.e. Ma Bell) enjoyed a monopoly over the markets they served. For example, by law, only Pacific Bell could deliver local phone service to California. After the act passed, multiple competing telcos could serve the same markets, with the new entrants known as CLECs.

CO - Central Office = acronym used in reference to the telco company's primary hub, or their physical building where their switching equipment is located.

codec - coder/decoder

co-locate = many small businesses do not store their own voice and data hardware within their place of business, and instead hire a hosting service provider to manage and maintain their backend systems at the hosting provider's remote location.

convergence = just years ago, voice and data networks were two different things, two different media. Now, thanks to IP, voice and data applications are melding together on the same network, using the same hardware and software, improving productivity while minimizing costs.

CRM - Customer Relationship Management = not commonly associated with the telecom and VoIP world, but growing more important as phone systems and customer contact information grows more intertwined, especially in call center environments.

CTI - Computer Telephony Integration = an ambiguously used term in reference to the ability for various applications to be accesses and controlled via a desk phone and a computer with the interaction between each being coordinated and integrated.

DID - Direct-inward-dialing = the ability for an outside caller to reach an extension on a PBX by dialing a direct number (310-555-1212) instead of having to dial an extension first (310-555-1000 x212).

DoS - Denial of Service = a type of VoIP security threat launched a malicious external attacker to render a VoIP phone system useless by bombarding it with an overwhelming volume of service requests, thus clogging up the system's resources.

DTMF - Dual-tone Multi-frequency = the type of audio signal created from pressing the keys on a touch-tone telephone (how the phone system differentiates between the 1 and the 2 on the phone keypad).

e911 - enhanced 911 emergency service = a North American (U.S. and Canada) telephone network feature for 911 emergency calling that automatically associates a phone number with a given physical address.

echo = echo in the telecom world is caused by various things (i.e. feedback resulting when a small portion of the caller's voice emitted over the phone handset's speaker feeds back into the same handset's receiver). In the VoIP world hybrid echo is the most common type, and is caused when a device called a hybrid, commonly used by telephone companies to turn a 2 pair wire into a 4 pair wire, has its impedance incorrectly set so that some of the calling parties voice is bounced back, thus distorting the caller's voice in his/her own ear.

Ethernet = frame-based computer networking technology commonly used in office networks (LANs).

FMC - Fixed Mobile Convergence = the acronym in reference to static (fixed) and wireless (mobile) networks evolving to allow seamless transition from one to the other (ex. you can start a business call on your cell phone at home in the morning, and when you arrive in the office, your cell phone will automatically transfer your business call over to the company's phone system via WiFi).

FXO - Foreign Exchange Office = the interface that sends/receives POTS service to the telephone company's central office (CO) that must be connected to the central office equipment (it's what connects POTS lines to IP PBXs!)

FXS - Foreign Exchange Subscriber = the interface that delivers POTS service from the telephone company's central office (CO) that must be connected to the subscriber's equipment (it's what connects regular analog phones to IP PBXs!)

G.711 - most commonly used codec for transmitting VoIP calls that 90KB for the first established call and 64KB for all subsequent calls. Recognized as having the best sound quality.

G.729 - an alternative codec that compresses data transmission so less than 10KB of bandwidth is required for each call. Known to strain the PBX system's CPU resources and has lesser sound quality.

GigE - Gigabit Ethernet = transmission medium allowing up to 1000MB of Ethernet bandwidth

H.323 - an ITU standard for transmitting real-time interactive voice and videoconferencing over networks. Commonly recognized as an obsolete VoIP protocol.

hosted IP = sometimes referred to as IP Centrex. Business class phone service delivered by a service provider that hosts the necessary PBX hardware and software at their colocation premise, so you don't have to own and maintain it yourself.

Internet Telephony = also known as IP Telephony or VoIP, and refers to all the hardware and software systems in place that allow for the transmission of packetized voice of IP networks.

ILEC - Incumbent Local Exchange Carrier = the opposite of CLEC, ILECs are the established legacy phone companies that were spawned from the old AT&T (Ma Bell). Examples include Pacific Bell (which was acquired by SBC which then was renamed AT&T - wow, such irony!), Nynex, GTE, Qwest, and Southern Bell.

IP - Internet Protocol = the standard protocol for transmitting data packets across

IP PBX - Internet Protocol Private Branch Exchange = modern PBX platforms that use IP software-based switching instead of hardware-based switching of legacy key systems and TDM PBXs.

ISDN - Integrated Services Digital Network = a circuit-switched telephone network system designed to allow digital transmission of voice and data over regular copper wires. Still widely in use but considered mostly obsolete.

ITSP - Internet Telephony Service Provider = an Internet service provider offering telephone service over VoIP, usually with the SIP, IAX, or H.323 protocols.

jitter = the sometimes common, but unwanted variation in voice signal clarity resulting from packet loss (voice packets getting lost or arriving out of sequence). Makes the person on the other end of the phone sound like they're underwater!

key system = see KSU below.

KSU - Key System Unit = now recognized as a legacy solution, key systems are multi-line analog phone systems with each phone having an individual button/light for each available line on the system. Known for their reliability, but with a feature list non-existent compared to modern IP PBX phone systems.

LAN - Local Area Network = typically found in office environments, the network of computers, printers, servers, routers, and other IP devices usually linked together via Ethernet or CAt-5e cabling.

latency = the delay in the arrival and assembly of IP voice packets at their destination caused by physical distance, number of hops across network nodes, encryption, and QoS policies. The cause of jitter.

LNP - Local Number Portability = see "number portability" below.

modem - modulator/demodulator

MPLS - Multi-Protocol Label Switching = a robust data transmission method used in the WAN using packet-switched networking to carry a variety of traffic types, including IP, ATM, SONET, and Ethernet.

number portability = remember the days when you had to get a new phone number from the phone company whenever you moved or switched carriers? In the VoIP world service providers and carriers are required to share and transfer a customer's phone number if that customer moves physical addresses or switches to a new carrier.

open source = a simple term with a long history, it originally stems from the "Freeware Summit", a meeting in 1998 of the "godfathers" of the most important open source software projects at the time. After deciding "free software" was misleading, the group decided on the term "open source" to refer to the community principals of accessing and writing software by keeping the source code openly available. Still often confused in the marketplace with being "free," it actually defines if the source code was developed in the open community as opposed to proprietary software being owned and controlled by a private entity.

P2P - Point-to-Point = acronym to describing a direct connection, digital or IP, between two remote office locations.

PBX - Private Branch Exchange = a telephone switching platform commonly used in business locations for connecting internal extensions and outside telephone lines.

POP - Point of Presense = term used in reference to the physical location of a telco company's/service provider's physical building where they keep their switching hardware and IP routers.

POTS - Plain Old Telephone Service = a common acronym in reference to the 100 year old network of copper wires built by good ol' Ma Bell (bless her heart!)

PSTN - Public Switched Telephone Network = the standard professional acronym in reference to the legacy Ma Bell switched-based network that's still alive and well today, and will be for many more years, even given all the VoIP hype.

QoS - Quality of Service = the method used by network routers and switches to prioritize data packets based on type. For example, voice packets take highest priority since their delivery is time sensitive

SIP - Session Initiation Protocol = standardized IP telephony protocol used for establishing and tearing down voice and data communication sessions between IP devices (see SIP Trunk).

SIP Trunk = a dynamic IP circuit that dynamically allocates available bandwidth between voice calls and data/Internet connectivity as needed. Seen as a modern replacement for legacy T1s, where available.

RJ-45 - registered jack = the standardized physical interface for connecting telecommunications equipment, especially phones.

T1 = originally known as DS-1, digital data and/or voice circuit that transmits 1.544 Mbps of data and/or 23 voice channels + 1 data channel.

T3 = originally known as DS-3, big brother to the T1/DS-1, a digital circuit able to carry 44.736 Mbps of data.

UC - Unified Communications = a common term for the integration of different communications systems and media across various devices and applications. For example, voicemail-to-email allows voicemail messages to be sent to an email account as an audio file.

VLAN - Virtual Local Area Network = thanks to IP sub-addresses and DNS proxies, multiple "virtual" networks can be configured on a single LAN. In other words, you do *not* need to run two separate physical cables to have multiple independent networks.

VoIP - Voice over Internet Protocol (commonly pronounced "voh-eep") = method for packetizing voice signals and transmitting them over an IP (Internet Protocol) network.

VPN - Virtual Private Network = the method used to create a secured, encrypted data tunnel or "pipe" between two remote locations. Often required for the use of IP phones in a remote office.

WAN - Wide Area Network = an ambiguously used acronym in reference to any part of the network that lies outside an office itself, or past the telco company's demarcation line.

Wi-Fi - Wireless Fidelity = the wireless technology brand began by the WiFi Alliance, turned into a common term in reference to the IEEE 802.11 wireless standard commonly in use today supporting wireless network applications, such as VoIP and laptop connectivity.

www - world wide web = the globalized commercial domain of networked public IP devices that overlays the Internet.

OfficeVoIPSolutions.com's Homepage