Vehicle Location Tracking Device. See Location Tracking.


Very Low Frequency. That portion of the electromagnetic spectrum having continuous frequencies ranging from about 3 Hz to 30 kHz.


Novell Virtual Loadable Module network client architecture uses packet burst technology, so ample packets are sent without waiting for packet acknowledgement . VLM support (compared with the old IPX) improves transfer times, especially for compressible files, since there is no waiting for acknowledgement.


Visitors' Location Register. A wireless telecommunications term . A local database maintained by the cellular provider in whose territory you are roaming. When you place a call in a roaming scenario, the local provider queries the HLR (Home Location Register) over the SS7 network through the use of a REGNOT (REGistration NOTification). The HLR is maintained by your cellular provider of record in order to verify your legitimacy and to secure your profile of features. The HLR responds to the REGNOT with a "regnot" (lower case), and transfers the necessary data. This information is maintained by the local provider as long as you remain an active roamer within that area of coverage. This process of query and download is accomplished via SS7 links between SCPs (Signal Control Points). SCPs typically are associated with MSCs (Mobile services Switching Centers), also known as MTSOs (Mobile Traffic Switching Offices) for registering visiting mobile station users. VLRs and HLRs are employed in a variety of cellular networks, including AMPS, GSM and PCS. See also AMPS, GSM, HLR, MSC and PCS.


Very Large Scale Integration. The art of putting hundreds of thousands of transistors onto a single quarter-inch square integrated circuit. Compare with LSI and ULSI.


  1. Voice Mail, Voice Messaging or Virtual memory. See Virtual Storage and Voice Mail.

  2. Virtual Machine. IBM's mainframe operating system.

  3. Virtual Machine. See Java Virtual Machine.


Acronym for "VersaModule-Eurocard." A one through 21 slot, mechanical and electrical bus standard originally developed by the Munich, Germany division of Motorola in the late 70s. VME uses most of the bus structure from then current Motorola's VersaBus board standard along with the newly developed DIN 41612 standard pin-in-socket connector for enhanced reliability. After years of work, VME was finally adopted by the ANSI/IEEE in 1987 (as ANSI/IEEE-1014). VME is known in Europe as the IEC 821 bus. This makes it an open standard. The VME backplane runs at 80 Mbytes per second. It is the most common bus on big open computers (i.e. ones larger than the PC). As of writing, there were over 300 vendors offering more than 3,000 off-the-shelf VME products. The IEEE standard is soon to lapse and be replaced by an extended VME64 specification, now in ANSI ballot being conducted by VITA. See also VMEBus and VXI.


An enhanced VME bus standard which includes multiplexed address and data cycles with 40 and 64 bit address modes and 64 bit data transfer modes allowing up to 80 MB/s transfer speed. This standard is under the ANSI ballot process conducted by VITA. See VME.

VME64 Extensions

A VITA draft standard that provides extra functionality to VME64 including 5 row J1/P1 and J2/P2 connectors that support live insertion on both 3U and 6U VME boards . Other features: 3.3V power, more grounds, ETL (slew rate) drivers, geographic addressing (slot ID) as well as support for parity, a serial diagnostic bus, JTAG test support and lots of user I/O. Some mechanical features: locking extractors , RFI gasketing, and ESD chassis discharge strips . See VME.


VersaModule-Eurocard BUS. A 32-bit bus developed by Motorola, Signetics, Mostek and Thompson CSF. Used widely in industrial, commercial and military applications with over 300 manufacturers of VMEbus products worldwide. VME64 is an expanded version that provides 64-bit data transfer and addressing.


Voice Messaging Educational Committee. An organization formed by voice messaging manufacturers and service providers to promote a better understanding of voice mail and its business benefits, and to help business implement voice mail systems in ways that meet the needs of callers and mailbox owners alike. See VME.


Validation Message Fraud


Voice Messaging Interface.


Validation Message Fraud


David Hester wrote to me: "I work for an ISP. We buy dial up service from providers in areas where we do not have our own POPs. We call these POPs Vendor Managed Networks or VMNs. We used to call them Other Peoples' Networks, or OPNs, but that term has been depricated by VMN. I think that the term VMN is a more descriptive term and could be useful to others in the telecom field."


Violation Monitoring and Removal. The process of removing a violations which are detected , so that violations do not propagate beyond the maintenance span.


Virtual Memory System

VMS OSI Transport Services

VOTS. A Digital Equipment Corp. software product that modifies Digital's DECnet transport layer to conform to the International Standards Organization (ISO) Transport Protocol Class Four (TP4).


Voice Messaging User Interface Forum. A standards body formed by voice messaging end users, service providers and manufacturers to define a minimum set of common human interface specifications for voice messaging systems.


Voice Message Exchange. One day in 1979, Gordon Matthews came back from lunch and noticed that he had received the usual half dozen messages that had been randomly written down semi-correctly by a harried receptionist . Already a noted inventor , Matthews saw an opportunity to build an adjunct device to the company phone system which would allow these messages to be recorded by the caller without an intermediary (i.e. a harried secretary) and would allow the recipient to electronically store these messages, forward them to others or to directly reply to them if they were generated from another internal extension. He called this device the Voice Message Exchange, and the company later became VMX, which later got bought by Octel, which later got bought by Lucent, which hasn't been bought by anyone , yet.


Virtual private NETwork. An MCI (now MCI Worldcom) term for a service it offers to customers who want to join geographically dispersed switches (typically PBXs). Instead of private lines joining the PBX, Vnet uses fast switched lines.


Via Net Loss. A loss objective for trunks, the value of which has been selected to obtain a satisfactory balance between two data terminals for the duration of the call. Loss value in db assigned to a circuit to compensate for it's added propagation delay, terminal delay or loss variability. Example: VNL for Satellite channels is 4db; VNL for Microwave channels is 0.0015 x route miles; All other terrestrial is +0.4db.


Voice News Network.


See Virtual Network Operator.


Virtual Network Services. A VPN (Virtual Private Network) term, referring specifically to a range of international VPN services, including voice, data, Internet and multimedia. Providers of traditional VNS include AT&T, MCI, Qwest and Sprint. During the recent past, groups of international carriers have formed multilateral affiliations to provide VNS seam- lessly, providing identical feature content and functionality across national borders, regardless of the affiliated country of origination or termination. Some of these ventures have failed.


Verification Office.


Variable Optical Attenuator.


Voice over ATM. Voice Over ATM. Voice over ATM enables an ATM switch to carry voice traffic (for example, voice telephone calls and faxes) over an ATM network. When sending voice traffic over ATM, the voice traffic is encapsulated using AAL1/AAL2 ATM packets.


Voice Over Broadband.


Voice Over BroadBand.


In February, 1996 a newspaper called, Investor's Business Daily, ran a story entitled "Is Your Office at Home Making You Sick?" It said that more than 20 million American workers are telecommuting , with another 20 million owning home based businesses. "Experts are finding that home based offices outfitted with the latest fax machines, photocopiers, laser printers and personal computers often foster unhealthy environments. Office machinery emits air pollutants called volatile organic compounds , or VOCs, which can make your head hurt and irritate your eyes, nose and throat. VOCs are also known to cause more serious health problems, including kidney and liver damage, experts say."

Vocabulary Development

Development of specific word sets to be used for speaker independent recognition applications.


Voice coder . A device that synthesizes speech. Vocoders use a speech analyzer to convert analog waveforms into narrowband digital signals. They are used in digital cellular phones as well as in the entertainment business (e.g., the voice of Darth Vader in Star Wars). Vocoders are an early type of voice coder, consisting of a speech analyzer and a speech synthesizer. The analyzer circuitry converts analog speech waveforms into digital signals. The synthesizer converts the digital signals into artificial speech sounds. For COMSEC purposes, a vocoder may be used in conjunction with a key generator and a modulator -demodulator device to transmit digitally encrypted speech signals over normal narrow- band voice communication channels. These devices are used to reduce the bandwidth requirements for transmitting digitized speech signals. There are analog vocoders that move incoming signals from one portion of the spectrum to another portion.


Video On Demand. At one stage it was considered a gigantic potential money maker for the phone companies who were real interested in getting into this market. Now it doesn't seem so hot. See NVOD and Video on Demand.


Voice Operated Device Anti-Sing. A device used to prevent the overall voice frequency singing of a two-way telephone circuit by ensuring that transmission can occur in only one direction at any given instant.


Experts recommend using vodka as a cleaning solution for diamond jewelry .


Voice over a DSL line ” Digital Subscriber Line. Voice phone calls over DSL. It's making a voice phone call over a digital subscriber line. See DSL.


Voice over Frame Relay is the transmission of voice over a Frame Relay network, VoFR is one of a family of "Voice over Packet" technologies that includes VoATM (Voice over ATM) and VoIP (Voice over Internet Protocol). Frame Relay was developed specifically for LAN-to-LAN internetworking across a WAN (Wide Area Network), and works quite well in support of such traffic. LAN traffic has no expectations in terms of QoS (Quality of Service) ” meaning it may be delayed by more important voice calls ” and Frame Relay inherently offers none. Voice, on the other hand, is quite demanding in terms of QoS, and that poses a problem. In order to provide some reasonable level of performance for voice. Therefore, VoFR employs several mechanisms.

First, manufacturers have developed routers that allow carriers to offer various levels of service through non-standard priority queuing mechanisms. VoFR frames can be marked as high priority and, therefore, have priority in the queuing buffers on both the inbound and outbound router ports. Frames carrying traffic of lower priority (e.g., LAN and SDLC data traffic) would be marked as such, and would have lower priority in the queuing buffers. While these mechanisms can be fairly effective, they are "best effort" in nature, offering no QoS guarantees .

Second, VoFR employs voice compression algorithms in order to improve performance. Voice, of course, always is analog in its native form. To support voice over a digital network of any sort , including Frame Relay, it first is converted to PCM (Pulse Code Modulation) format, according to the ITU-T G.711 standard. PCM takes several forms. In North America, u Law (actually mu Law, but my text editor won't support the symbol for "mu"), which is based on the Nyquist Theorem, is the choice. In Europe and internationally, A Law, which is based on Shannon's Law, is used. The two approaches are similar in concept, but different enough to be incompatible. Nonetheless, each is used to encode an analog voice stream of 4 KHz into a digital format requiring bandwidth of 64 Kbps. The analog voice signal is sampled 8000 times a second, with each sample coded into an 8- bit byte (8,000 x 8 = 64,000) at very precise intervals of 125 microseconds (millionths of a second). As each byte is formed, it is sent in a time slot across a channelized digital circuit in the form of T-carrier (North America) or E-carrier (Europe and international). On the receiving end, the process is reversed and the analog signal is reconstructed. This approach works perfectly, but requires that circuit-switches be in place to support perfectly committed connectivity. As a packet data technology, Frame Relay will not support the precise pace demanded by PCM-encoded voice. Even if each voice byte were encapsulated into a frame and the frames were sent into the network 8000 times a second at the precise pace of every 125 microseconds, the Frame Relay network couldn't provide any guarantees that they would make it through the network and to the other end at the same pace. In fact, I can guarantee you that they wouldn't. A good compression algorithm addresses the problem in several ways. First, compression reduces the pressure on bandwidth through the various switches and routers, and across the circuits that interconnect them. Second, the delay imposed on the voice traffic by the very process of decompressing a voice frame provides the receiving VFRAD (Voice Frame Relay Access Device) with a few milliseconds (thousandths of seconds) of time to seize the next voice frame and blend them together. The compression techniques employed also include various predictive techniques that enable them to predict the essence of the voice data contained in subsequent frames based on the voice data contained in previous frames. This capability is based on the fact that voice data flows in a fairly smooth pattern of amplitude (i.e., volume) and frequency (i.e., pitch) that is highly predictable. That allows the stretching and blending of voice data in the event that a subsequent frame is lost, errored or excessively delayed as it transits the network. While proprietary compression algorithms were developed by some manufacturers and are used by some carriers, the Frame Relay Forum specified several standard approaches in its FRF.11 IA (Implementation Agreement). Early implementations of VoFR were based on PCM, which clearly is an unsatisfactory approach. Subsequently, ADPCM (Adaptive Differential Pulse Code Modulation), standardized by the ITU-T as G.726 and included in FRF.11, gained favor. ADPCM is a popular and well understood technique that is used in some traditional PSTNs (Public Switched Telephone Networks) to yield 2:1 (twoto-one) compression, thereby requiring only 32 Kbps for "toll quality" voice. In VoFR implementations it variously compresses PCM voice to 40, 32, 24, and even 16 Kbps. As the compression rate increases , the bandwidth required decreases proportionately, but the reconstructed voice quality suffers. ADPCM does not include any predictive capability. The predictive algorithm included in FRF.11 is CS-ACELP (Conjugate Structure-Algebraic Code Excited Linear Predication), standardized by the ITU-T as G.729. CS-ACELP yields an 8:1 compression rate, which requires only 8 Kbps for voice, with some degradation in the quality of the reconstructed voice signal. Although they are not included in FRF.11, other standard compression algorithms also are used in support of VoFR. Those algorithms include Dual Rate Speech Coder for Multimedia Communication, which runs at rates of 6.3 and 5.3 Kbps, and is specified in G.723; and LD-CELP (Low Delay-Code Excited Linear Prediction), which runs at 16 Kbps, and is specified in G.728.

Third, various mechanisms have been developed to select different paths through the network. Most significant among these is MPLS (MultiProtocol Label Switching), which was standardized by the IETF (Internet Engineering Task Force) and which is based on Cisco's proprietary Tag Switching protocol. MPLS is capable of selecting a high bandwidth, low latency path through the network in support of VoFR. In addition to priority queuing and compression mechanisms, VoFR benefits from plenty of bandwidth in the Frame Relay network core. This responsibility is entirely the carrier's. If the switches or circuits along a particular VoFR path in the network core are overloaded or undersized, VoFR performance will suffer considerably. VoFR also depends on the CIR (Committed Information Rate), which is a contractual bandwidth commitment between the end user and the carrier. If the CIR is under- sized by the end user organization in consideration of economics, VoFR performance will suffer. Finally, VoFR frames must be prioritized by the transmitting FRAD in terms of Discard Eligibility (DE). Clearly, the VoFR frames must not be marked as DE. If they are so marked, the network will discard them first in the event of congestion. Now, you must be asking yourself why anyone would even consider VoFR. I asked that question. Long distance rates over the circuit-switched PSTN are today in the range of 2-7 cents per minute, depending on how big your company is and how good a negotiator you are. VoIP is getting all of the attention. VoFR seems like a lot of trouble for voice of highly uncertain quality. Well, the reason people use it for voice is that it's free or can be free ” if you've got a Frame Relay network in place, there is some capacity available at the moment within the CIR, and the network is not advising you of any congestion at the moment, you can compress some voice and send it between two corporate sites on the Frame Relay network for free. Frame Relay is priced on the basis of port speed, local loop speed, CIR speed, and occasionally some other elements. There is no usage-sensitive element to the pricing algorithm. The quality usually is pretty good, although it sometimes gets to be pretty bad during the course of a call. You would never install a Frame Relay network specifically for voice. You install it for data, and voice rides for free from time-to-time. That's the whole story. See also ACELP, ADPCM, CELP, CIR, Compression, CS-ACELP, DE, Dual Rate Speech Coder for Multimedia Communication, FRAD, Frame Relay, LD-CELP, MPLS, PCM, Tag Switching, VoATM, and VoIP.


Voice-Operated Gain Adjusting Device. A voice-operated compressor circuit that is designed to provide a near-constant level of output signal from a range of input amplitudes. Such a circuit has a fast attack time with a relatively slow release time to avoid excess volume compression at the system output.


Voice over HDLC

Voice Activated Dialing

A feature that permits you to dial a number by calling that number out to your cellular phone, instead of punching it in yourself. See Voice Activated Video.

Voice Activated Switching

Used in multipoint video conferencing so all sites automatically see the video of the person speaking.

Voice Activated Video

A microphone/camera that is activated in response to voice. Imagine you're watching a videoconference going on in four locations. You can hear what everyone is saying. What you need is to be able to see the person who is speaking the loudest, and therefore, presumably the principal speaker ” the person whose attention everyone should be focused on. In voice activated video, the videoconferencing system senses who's speaking the loudest and throws that person's face up on everyone's screen.

Voice Activity Compression

VAC. A method of conserving transmission capacity by not transmitting pauses in speech.

Voice Activity Detection

See VAD.

Voice Application Network

A third-party provider of call-center integration. These networks typically offer clients network and voice recognition infrastructure, charging for time the application is used. Further, they allow organizations to offer their customers self-service access to voice-activated applications. For example, insurance companies can use a Voice Application Network to allow agents and customers to easily access the status of a bill payment or a claim. See also Voice Portal, VXML.

Voice Applications Program

System software providing the necessary logic to carry out the functions requested by telephone system users. It is responsible for actual call processing, making the various voice connections and providing user features, such as Call Forwarding, Speed Dialing, Conference, etc.

Voice Board

Also called a voice card or speech card. A Voice Board is an IBM PC- or AT-compatible expansion card which can perform voice processing functions. A voice board has several important characteristics: It has a computer bus connection. It has a telephone line interface. It typically has a voice bus connection. And it supports one of several operating systems, e.g. MS-DOS, UNIX. At a minimum, a voice board will usually include support for going on and off-hook (answering, initiating and terminating a call); notification of call termination (hang-up detection); sending flash hook; and dialing digits (touchtone and rotary ). See Voice Bus and VRU.

Voice Body Part

An X.400 term. A body part sent or forwarded from an originator to a recipient which conveys voice encoded data and related information. The related information consists of parameters which are used to assist in the processing of voice data. These parameters include information detailing the duration of the voice data, the voice encoding algorithm used to encode the voice data, and supplementary information.

Voice Browser

Pick up a phone, call a VoxML-enabled Web site, ask it questions using your voice and what's known as "natural voice commands" (such as "When is my plane leaving?") and hear responses to your questions. This uses an upcoming technology called Voice Markup Language (VoxML), which several manufacturers plan to develop as an open platform and submit to the World Wide Web Consortium for standards approval. The idea is to VoxML-enable your Web site so it can respond to voice recognition.

Voice Bulletin Boards

These are voice mailboxes which contain pre-recorded information that can be updated as frequently as the provider of the mailboxes desires and can be accessed by the public 24 hours a day. Voice bulletin boards can be used by city or county departments which receive a large number of calls asking for routine information, e.g., summer programs for kids as listed by a parks and recreation department; jobs currently open in the city as listed by the personnel departments; etc.

Voice Bus

Picture an open PC. Peer down into it. At the bottom of the PC, you'll see a printed circuit board containing chips and empty connectors. That board is called the motherboard. Fatherboards are inserted into the connectors on the motherboard. These fatherboards do things on the PC ” like pump out video to your screen or material to your printer or your local area network. The motherboard controls which device does what WHEN by sending signals along the motherboard's data bus ” basically a circuit that connects all the various fatherboards through their connectors. That data bus was not designed for voice. For voice you need another bus. Several voice processing manufacturers have addressed that need by creating a voice bus at the top of their PC-based voice processing cards. They have tiny pins sticking out of their cards. You attach a ribbon cable from one set of pins on one voice processing card to the next set on the adjacent card and then the next. There are several voice bus "standards." Two come from Dialogic. One is called AEB, Analog Expansion Bus. And one is called PEB, PC Expansion Bus (a digital version). One comes from a consortium of companies and is called MVIP. There are many advantages to having a voice bus. It gives you enormous flexibility to mix and match voice processing boards, like voice recognition, voice synthesis, switching, voice storage, etc. You can build really powerful voice processing systems inside today's fast '386 and '486 PCs with the great variety of voice processing now available. For more information on this exciting field, read TELECONNECT Magazine. 212-691-8215. See MVIP.

Voice Call

A telephone call established for the purpose of transmitting voice, rather than data.

Voice Calling

One manufacturer describes this as allowing a phone user to have calls automatically answered and connected to his phone's loudspeaker. Nortel defines voice calling as somewwhat differently. It says this feature allows a voice announcement to be made, or a conversation to begin, through the speaker of another telephone in the system.

Voice Carry Over

VCO. A reduced form of TRS (Telecommunication Relay Service) where the person with the hearing disability speaks directly to the other end users. The Communications Assistant then types the response back to the person with the hearing disability. The Communications Assistant does not voice the conversation.

Voice Channel

A channel suitable for transmission of speech, analog or digital data, or facsimile .

Voice Circuit

A circuit able to carry one telephone conversation or its equivalent, i.e. the typical analog telephone channel coming into your house or office. It's the standard subunit in which telecommunication capacity is counted. It has a bandwidth between 300 Hz and 3000 Hz. The U.S. analog equivalent is 3 KHz. The digital equivalent is 56 Kbps in North American and 64 Kbps in Europe. This is not sufficient for high fidelity voice transmission. You'd probably need at least 10,000 Hz. But it's sufficient to recognize and understand the person on the other end.

Voice Coil

The element in a dynamic microphone which vibrates when sound waves strike it. The coil of wire in a loudspeaker through which audio frequency current is sent to produce vibrations of the cone and reproduction of sound.

Voice Commerce

See V-Commerce.

Voice Compression

Process of reducing a voice signal to use less bandwidth during transmission. That's the obvious meaning. In telecommunications where voice was originally encoded digitally at 64 Kbps using PCM, voice compression now means to compress a voice channel to obtain a channel of 32 Kbps or fewer, nowadays to under 10 Kbps. See VoIP.

Voice Connecting Arrangement

VCA. A device that, once upon a time, was necessary for connecting your own phone system to the nation's switched telephone network. Most phones now meet FCC (and other) safety standards, so VCAs are no longer necessary. Most phone systems (as opposed to phones) do have internal protection circuitry, as shown by the "F" (for fully protected) in their FCC registration number. The VCA was once called a Protective Connecting Arrangement (PCA).

Voice Coupler

An interface arrangement once provided by the telephone company to permit direct electrical connection of customer-provided voice terminal equipment to the national telephone network. No longer needed because of the FCC's Registration Program.

Voice Data

An SCSA definition. Encoded audio data.

Voice Dialing

The ability to tell your phone to dial by talking to it. Say, "Call Police" and it will automatically dial the police. This feature has enormous benefits for handicapped people. It will have greater benefits for normal people when the technology of voice recognition improves.

Voice Digitization

The conversion of an analog voice signal into binary (digital) bits for storage or transmission.

Voice Driver

A Dialogic product that comes for MS-DOS, OS/2 and UNIX. In MSDOS, it is a terminate and stay resident (TSR) program which acts as a central server for MS-DOS based applications. It provides all of the services required to support installable device drivers for each hardware component and for the application. See also Device Driver.

Voice DTMF Forms Applications

This Voice DTMF (DUAL TONE MULTIPLE FREQUENCY) application allows a use of a voice mail system to take specific information from its customers 24 hours a day. By prompting callers to respond by speaking or pressing the keys of their touchtone phones, a city department, for example, could plan service calls, building inspections or send out appropriate forms.

Voice Extensible Markup Language


Voice Frame

See VFRAD and FRF11.

Voice Frequency

VF. Any of the frequencies in the band 300-3,400 Hz that are transmitted in telephony systems to reproduce human speech voice with reasonable fidelity. Some Oriental languages have less than satisfactory results with this narrow a band, and emerging ISDN implementations are increasing it for them. See Voice Frequencies.

Voice Frequencies

VF. Those frequencies lying within that part of the audio range that is employed for the transmission of speech. In telephony, the usable voice frequency band ranges from a nominal 300 Hz to 3400 Hz. In telephony, the bandwidth allocated for a single voice frequency transmission channel is usually 4 KHz, including guard bands.

Voice Frequency Telegraph System

A telegraph system permitting use of up to 20 channels on a single voice circuit by frequency division multiplexing.

Voice Grade

A communications channel which can transmit and receive voice conversation in the range of 300 Hertz to 3000 Hertz.

Voice Grade Channel/Voice Grade Facility

VGF. A line suitable for voice, low-speed data, facsimile, or telegraph service. Generally , it has a frequency range of about 300-3000 Hz.

Voice Grade Wiring

The term generally refers to analog lines with the bandwidth required to transmit human voice, typically about four thousand Hertz (4KHz).

Voice Hogging

See Voice Switched.

Voice Integration

Allows computer fax solutions to be store and forward hubs for both image as well as voice communication. Many of these products work on PC-based systems and offer all the capabilities of a message center.

Voice Interface Card

See VIC.

Voice Logger

A device that companies use to record their employees ' phone calls. A voice logger is typically used in a brokerage firm or a call center. It attaches to your phone system and allows you to find calls in many ways ” from which person, which extension, which incoming trunk, what time of day, what 800 line, etc. See also DID.

Voice Jail

A poorly designed voicemail system that has so many submenus one gets lost and has to hang up and call back. Also called Voice Mail Jail.

Voice Mail

Voice Mail allows you to receive, edit and forward messages to one or more voice mailboxes in your company or in your universe of friends . With voice mail, employees can have their own private mailboxes. Here's an explanation of how it works: You call a number. A machine answers. "Sorry. I'm not in. Leave me a message and I'll call you back." It could be a $50 answering machine. Or it could be a $200,000 voice mail "system." The primary purpose is the same ” to leave someone a message. After that, the differences become profound. a voice mail system lets you handle a voice message as you would a paper message. You can copy it, store it, send it to one or many people, with or without your own comments. When voice mail helps business, it has enormous benefits. When it's abused ” such as when people "hide" behind it and never return their messages ” it's useless. Some people hate voice mail. Some people love it. It's clearly here to stay.

In the fall of 1991, the Wall Street Journal carried a story negative on voice mail. Les Lesniak, Rolm's Senior VP Marketing disagreed. His reply published in the Journal is one of the finest explanations of voice mail's virtues:

"The writer's observations ignore the way today's voice communication technology is making communication between people easier and more convenient , and is elevating the level of service savvy companies provide their customers. Manufacturers use it to take orders after hours and on weekends. Financial services companies use it to provide account information to customers on a 24- hour basis. Colleges use it to register students. A retail executive uses it to broadcast messages to her staff. And a lawyer uses it to respond to calls when traveling.

"Voice messaging keeps calls confidential, simplifies decision making, saves time and money, eliminates inaccurate messages and "telephone tag," allows people to use their time more productively. In short, it keeps communication crisp, clear and constant. The writer's line of thinking would demand that people remain at their desk 24 hours a day. If they don't, the phone goes unanswered, a receptionist answers the phone and takes a message, or an answering machine records the message and cuts off the caller at will. None of these scenarios is ideal.

"To be successful, voice mail technology must be understood by users and supported by top management, And it must meet the needs of the customer. Training for all employees must be mandatory and the system must be administered and managed properly. 'Must answer' lines and greetings that are changed daily are only two ideas that make voice mail not just helpful, but essential to customer service and an enhanced company image.

"Contrary to the writer's view, voice mail contributes to effective business communication and is far superior to an unanswered phone call, a misplaced message or an answering machine." here are some statistics which add weight to voice mail's logic:

  • 75% of all business calls are not completed on the first attempt.

  • This can easily waste $50 to $150 per employee per month in toll charges.

  • Half of the calls are for one-way transfers of information.

  • Two thirds of all-phone calls are less important than the work they interrupt.

  • The average length of a voice mail message is 43 seconds. The average long distance call is 3.4 minutes. Voice mail is 80% faster. Here are the standard benefits of voice mail:

    1. No more "telephone tag." Voice mail improves communications. It lets people communicate in non-real time.

    2. Shorter calls. When you leave messages on voice mail, your calls are invariably shorter. You get right to the point. Live communications encourage "chit chat" - wasting time and money.

    3. No more time zone/business hour dilemma. No more waiting till noon (or rising at 6 A.M.) to call bi-coastally or across continents.

    4. Reduce labor costs, Instead of answering phones and taking messages, employees are free to do more vital tasks .

    5. Fewer callbacks. In some cases, as many as 50%.

    6. Improved message content. Voice mail is much more accurate and private than pink slips. Messages are in your own voice, with all the original intonations and inflections.

    7. Less paging and shorter holding times.

    8. Less peakload traffic.

    9. 24-hour availability.

    10. Better customer service.

    11. Voice mail allows work groups to stay in contact - morning, noon and night.

    12. Voice mail reduces unwanted interruptions. See also Voice Mail Jail and Voice Mail System.

Voice Mail Jail

What happens when you reach a voice mail message and you try and reach a human by punching "0" (zero) and you get transferred to another voice mail box and you try again by punching "0" or some other number you're told to punch...and you never reach a human. You're stuck forever inside the bowels of a voice mail machine, being instructed to go from one box to another, never reaching a real human. You're in voice mail jail.

Voice Mail System

A device to record, store and retrieve voice messages. There are two types of voice mail devices ” those which are "stand alone" and those which profess some integration with the user's phone system. A stand alone voice mail is not dissimilar to a collection of single person answering machines, with several added features. You can instruct the machines (voice mail boxes) to forward messages among themselves . You can organize to allocate your friends and business acquaintances their own mail boxes so they can dial, leave messages, pick up messages from you, pass messages to you, etc. You can also edit messages, add comments and deliver messages to a mailbox at a pre- arranged time. Messages can be tagged "urgent" or "non-urgent" or stored for future listening. The range of voice mail options varies among manufacturers.

An integrated voice mail system includes two additional features. First, it will tell you if you have any messages. It does this by lighting a light on your phone and/or putting a message on your phone's alphanumeric display. Second, if your phone rings for a certain number of rings (you set the number), the phone will transfer your caller automatically to your voice mail box, which will answer the phone, deliver a little "I am away" message and then receive and record the caller's message.

There are other levels of integration. You might have a phone which has "soft" buttons and an alphanumeric display. That display might label your phone's soft buttons like those on a cassette recorder ” forward, reverse, slow, fast, stop, etc. so you can go through your messages any way you like. Telenova has such a phone. It's very impressive.

There are pros and cons to voice mail systems. Some employees will hide behind them, forwarding calls from their customers into voice mail boxes and never returning them. Some employees will make good use of them. They dial in for their messages, research what the customer wants and return the voice mail calls quickly. Many voice mail systems are being combined with automated attendants. Many are being combined with interactive voice processing systems, including sophisticated tie-ins to mainframe databases. Some people hate voice mail systems. Others love them. It all depends on how the system is used, managed and sold. See also Voice Mail, Audiotex, Automated Attendants, Information Center Mailboxes, Enhanced Call Processing and Voice Processing.

Voice Management

Voice Management is a fancy term for managing the health and performance of a corporation's voice network. Real-time processing of voice call data enables these systems to actively calculate performance metrics such as trunk occupancy , port capacity on phone items like the corporation's main phone system, its IVR (interactive voice response), its voicemail, its ACD (automatic call distributor), etc. Voice management system administrators establish acceptable thresholds for performance and are notified (via page, email etc.) when their voice network does not meet these standards. Voice Management systems often provide a customized browser interface with one or more display panels to let you see how your network is performing. Views include:

  1. Trunk Performance: Displays the percent of circuits in a trunk group that are currently being utilized so technicians can determine if the group is under or over utilized, and optimize accordingly .

  2. Route Analysis: A panel that displays how inbound and outbound calls route through the network. For instance by watching how inbound calls are transferred from auto attendant ports, a technician can determine if certain toll-free numbers are correctly reaching the final appropriate extension. Outbound route analysis helps optimize Least-Cost Routing Systems by making sure that each call goes out over the appropriate route.

  3. Voice Over IP: By evaluating specific calling patterns, managers can determine the economic viability of implementing VoIP. Information provided also allows them to determine appropriate bandwidth requirements, based on volumes of traffic.

  4. Call Stats: A department manager can see a real-time display of call activity within their department, even from multiple remote sites. Sales Managers particularly like this functionality.

  5. System Alarms: Specific calls (i.e., 911) can be displayed at a receptionist's desk to direct emergency personnel where the call was originated. Technicians can be alerted to high trunk or port capacity conditions and quickly reroute calls to avoid an all-trunks-busy condition.

A Voice Management platform also manages the financial performance of a voice network as well. Budget warnings: Voice Management systems allows CFOs to allocate various telecom expenses across the enterprise and forecast upcoming year's budget requirements. Scheduled delivery of reports show variances of actual expenses compared to budgeted amounts.

Carrier tariff analysis: By analyzing existing carrier costs by specific call type (i.e. intralata, interstate), Voice Management systems enable users to compare alternative carrier plans to evaluate cost saving strategies.

Total Cost Of Ownership: The voice network now includes cell phones, pagers , DSL etc. Voice Management systems consolidate and report these expenses by cost centers so that executives can evaluate the total cost of ownership of their network

Jon A. Giberson of www.callaccounting.com helped compile this definition.

Voice Markup Language

See Voice Browser.

Voice merging

The oral tradition of African American preachers using another's words. See also Plagiarism.

Voice Message Service

A leased service typically over dial up phone lines which provides the ability for a phone user to access a voice mail system and leave a message for a particular phone user. See Voice Mail System

Voice Message Exchange

See VMX.

Voice Messaging

Recording, storing, playing and distributing phone messages. Essentially voice messaging takes the benefits of voice mail (such as bulk messaging) beyond the immediate office to almost any phone destination you select. Voice messaging is often done through service bureaus. At one point, Nynex (now called Verizon) saw voice messaging as four distinct areas:

  1. Voice Mail, where messages can be retrieved and played back at any time from a user's "voice mailbox";

  2. Call Answering, which routes calls made to a busy/no answer extension into a voice mailbox;

  3. Call Processing, which lets callers route themselves among voice mailboxes via their touchtone phones; and

  4. Information Mailbox, which stores general recorded information for callers to hear.

Voice Modem

A new type of modem which handles both voice and data over standard analog phone lines. A voice modem is the classic computer telephony device, since it applies intelligence to the making and receiving of normal analog phone calls. Such voice modem might be a full-duplex speakerphone and an answering machine / voice mail device. Such modem might be able to detect incoming and outgoing touchtone and other signals, such as Caller ID. Such modem might also include music on hold, pager dialing, bong and SIT tone detect, line break detect, local phone on / off detect, extension off hook detect, remote ring back detection and VoiceView. The thrust towards voice modems is coming from chip manufacturers, including Sierra Semiconductor, Rockwell and Cirrus Logic. Some standards bodies are working on voice modems. Two standards are emerging ” IS-101 and PN-3131.

Voice of God

You're about to give a speech. Someone has to introduce you. Suddenly, over the speakers you hear " Please welcome, all the way from New York, Mr. Harry Newton." That introduction is what's called, in that business, "the Voice of God."

Voice On The Net Coalition

An organization formed to stop regulatory attempts to stifle the growth of voice on the Internet. See VON Coalition. 802-878-9884 and www.von.org

Voice Operated Relay (VOX) Circuit

A voice-operated relay circuit that permits the equivalent of push-to-talk operation of a transmitter by the operator.

Voice Over

A feature on a phone system ” namely that while you are speaking to someone on the phone, your operator can talk to you "over" the conversation you're having. What happens is that you hear your operator in your telephone's handset receiver, but the person you're speaking with can't. You can reply to the operator (telling him/her you'll be one minute, please call back, etc.) by hitting a DND/MIC (Do Not Disturb/Microphone) button on your phone. Voice Over has major benefits. It saves on long distance calls you don't have to return. It closes deals that can't wait. And it gives customers immediate answers. In short, it improves corporate efficiency and customer satisfaction.

Voice over Frame Relay

See VoFR.

Voice over IP

VoIP. A VoIP (Voice over Internet Protocol) phone call is transmitted over a data network. The "Internet Protocol" is a catchall for the protocols and technology of encoding a voice call that allow the voice call to be slotted in between data calls on a data network. Such data network may be the public Internet, a corporate Intranet, or a managed network used by long, long distance and international traditional providers. VoIP phone calls, if properly engineered, sound just as good as a circuit switched TDM phone call ” the ones we make and receive every day. There are three main benefits to VoIP phone calls:

First, they may potentially be cheaper. Since the data network is typically charged on a flat rate and thus the marginal cost of making a VoIP is zero, how cheaper depends on

  1. The cost of terminating the VoIP call into the traditional phone network. Figure a penny a minute.

  2. The price of a standard circuit switched TDM call. They've been getting cheaper over the years.

  3. How much tax is levied on both. Taxes are horrendous on traditional circuit switched long distance calls. They aren't so big, yet, on VoIP calls, which are classified by some regulatory agencies as "information services," not voice phone calls. And therefore they escape most taxes.

Second, you may achieve benefits of managing a voice and data network as one network. If you have IP phones, moves, adds and changes will be easier and cheaper. IP phones are basically networked computers. They have individual numbers, with memories, user profiles. Their software upgrades are typically centrally managed using standard computing systems. In short, they're "user friendly" to manage and can largely be managed remotely.

Third, ” and the key attraction of IP telephony ” is added (and integrated) new services, including integrated messaging, voice emails, number portability, caller ID with name , call waiting, call forwarding, take your area code with you, plug into the Internet anywhere and make free calls from anywhere in the world. And best of all you can typically manage your phone via a Web site on the Internet, which will tell you which calls you made and received, etc. A VoIP phone is typically a much better animal than today's circuit switched phone. As I write this definition in early 2004, I'm about to switch all my phone calling over to a VoIP phone from Vonage. See Internet, Internet Protocol, Network Border Switch, Packet Switching, Skype and Vonage.

Voice over Multiservice Broadband Network


Voice Paging Access

Gives attendants and phone users the ability to dial loudspeaker paging equipment throughout the building. An unbelievably useful feature, if your people are prone to wander.

Voice Portal

Call a phone number, have an interactive voice response system answer you, respond to your words with speech recognition, read your emails or the news with text-to-speech skills, perhaps even allow you to "surf" the Web. The classic definition of a portal is a door, gate, or entrance , especially one of imposing appearance, as to a palace. In the Internet / World Wide Web business, a portal is a site, which the owner positions (through marketing) as an entrance to other sites on the Internet. There are two types of portals ” the conventional PC-based, browser based ” and the newer one using the telephone. For a bigger explanation of a portal, see Portal.

Voice Print

See Voiceprint.

Voice Processing

Think of voice processing as a voice computer. Where a computer has a keyboard for entering information, a voice processing system recognizes touch- tones from remote telephones. It may also recognize spoken words. Where a computer has a screen for showing results, a voice processing system uses a digitized synthesized voice to "read" the screen to the distant caller.

Whatever a computer can do, a voice processing system can too, from looking up train timetables to moving calls around a business (auto attendant) to taking messages (voice mail). The only limitation on a voice processing system is that you can't present as many alternatives on a phone as you can on a screen. The caller's brain simply can't remember more than a few. With voice processing, you have to present the menus in smaller chunks .

Voice processing is the broad term made up of two narrower terms ” call processing and content processing. Call processing consists of physically moving the call around. Think of call processing as switching. Content consists of actually doing something to the call's content, like digitizing it and storing it on a hard disk, or editing it, or recognizing it (voice recognition) or some purpose (e.g. using it as input into a computer program.) See Voice Board, Voice Response Unit and Voice Server.

Voice Profile for Internet Messaging


Voice Recognition

The ability of a machine to recognize your particular voice. This contrasts with speech recognition, which is different. Speech recognition is the ability of a machine to understand human speech ” yours and most everyone else's. Voice recognition needs training. Speech recognition doesn't. See Speaker Dependent and Speaker Independent Voice Recognition.

Voice Response Unit

VRU. Think of a Voice Response Unit (also called Interactive Voice Response Unit) as a voice computer. Where a computer has a keyboard for entering information, an IVR uses remote touchtone telephones. Where a computer has a screen for showing the results, an IVR uses a digitized synthesized voice to "read" the screen to the distant caller. An IVR can do whatever a computer can, from looking up train timetables to moving calls around an automatic call distributor (ACD). The only limitation on an IVR is that you can't present as many alternatives on a phone as you can on a screen. The caller's brain simply won't remember more than a few. With IVR, you have to present the menus in smaller chunks. See IVR and Voice Board.

Voice Retrieval

Message system that stores verbal messages (from callers or operator) for automatic retrieval at the customer's convenience.

Voice Ring

Multiple Digital Intertie Buses connected in series to all nodes. Provides extra channels for voice data transmission when direct link (DI) channels are busy.

Voice Server

A PC sitting on a LAN (Local Area Network) and containing voice files which are accessible by the PCs on the LAN. Such voice files may be transmitted on the LAN or over phone lines under the control of the PCs on the LAN. A voice server might contain voice mail. It might contain voice annotated electronic mail. Its primary function is to store voice in such a way that it's accessible easily. Voice servers are typically faster, have more disk capacity and more backup provisions than normal PCs. According to a letter I received in early May, 1993 from the lawyers for a company called Digital Sound Corporation, that company owns federal trademark registration number 1,324,258 for the mark Voiceserver, spelled as one word, not two.

Voice Service Personality

A new name for dial tone.

Voice Stop

Voice Stop is a means for callers to interrupt a menu prompt or other instruction on a voice processing system by merely speaking into the phone. This is a capability that is similar to pressing a digit on the touch-tone pad in order to stop a recording or a prompt from continuing. Unlike Voice Cut-Through, Voice Stop does not actually analyze the word being spoken. voice Stop technology senses energy on the telephone line and stops execution based on that energy. For example, a train whistle or over head loudspeaker could be transmitted over the phone and have the same effect.

Voice Store And Forward

Voice mail. A PBX service that allows voice messages to be stored digitally in secondary storage and retrieved remotely by dialing access and identification codes. See Voice Mail System.

Voice Switched

A device which responds to voice. When the device hears a voice, it turns on and transmits it, muting the receive side. The most common voice-switched device is the desk speakerphone. With voice switching, it's easy to hog a circuit. Just keep making a noise. Watch out for voice hogging. If you're calling someone and waiting for them by listening in on your speakerphone, mute your speakerphone. This way you'll hear them when they answer.

Voice Switching

Equipment used in voice and video conferences. The equipment is activated by sounds of sufficient amplitude; hopefully speech, but also loud noises. Fast switching activates microphones so that only one conference participant can speak at a time. See also Voice Activated Video.

Voice Terminal

A pretentious AT&T term for a Telephone.

Voice Verification

The process of verifying one's claimed identity through analyzing voice patterns.


A transmission service with a bandwidth considered suitable for transmission of audio signals. The frequency range generally is 300 or 500 hertz to 3,000 or 3,400 hertz ” the frequency range the common analog home phone service is made at.


A voice recognition term. A voiceprint is a speech template used to recognize and verify callers. For example, Home shopping Network. When a voiceprint system is operating, the user's speech is compared to the stored voiceprints. If they match, the system recognizes the word and executes the command.


VoiceXML (VXML) is a platform independent structured language created using the extensible markup language (XML) specification to deliver voice content through several different media like the web and phone systems. It has a format similar to other structured languages like HTML, however it is entirely defined within the XML standard specification. Voice XML provides a uniform development environment that allows a business to build on its web investments for voice including application integration code, business rules, and personalized software. Voice and web channels can share the same back end integrated databases facilitating a complete view for the customer, regardless of how they choose to interact with the enterprise. VoiceXML provides the framework for:

  • Delivering synthesized or digitized sound

  • Recognizing user input

  • Recording user input

  • Controlling call flow

  • Transferring and disconnecting callers

A VoiceXML document is composed of text elements and tags that instruct the system to provide the user with information and recognize user input as well as additional functions such as recording and transferring. Some VoiceXML tags that can be used to create content are:

  • Tag Function

    <assign> Assign a value to a variable

    <audio> Play an audio clip

    <block> A container of executable code

    <catch> Catch an event

The structure of a VXML document is very similar to an HTML document, even though the tags and syntax of the languages are different. However, the basic similarities of HTML and VXML make it easy for a savvy web developer to learn the syntax of VXML quickly and begin to create simple or complex voice interfaces without having to know the technical details of the voice system.

Like the traditional web server VXML follows the client / server model where a user can request information from a document server, the server responds with the appropriate content and an interpreter reads the document and presents the information to the client providing the advantages of web-based development and content delivery to interactive voice response applications.

For example, a person who wants to check their bank account balance to make sure they have enough money to write a check could call their bank and access their automated customer service department. If the phone system is configured with an interactive voice response system, it is able to present and guide the caller to the point where they can check their available balance. After entering their account number and password the caller is presented with a menu of options. The caller presses the keypad number, which sends a request for their available balance. That input is interpreted and a request for the available balance is sent to the document server. The document server accepts the request, looks up the account and authenticates the user from the previously entered information. Once the document server has authenticated the request it generates a VXML document containing the account balance. The VXML document is sent to the interpreter and processed . The information in the VXML document is then interpreted and used to create a synthesized voice response so the customer can hear how much money they have in the account. Using VXML the information presented to the caller is the same interface and database the caller would use if they were retrieving the info from their Web site. This ensures a consistent view regardless of the media used by the customer.

VoiceXML Forum

The VoiceXML Forum is an industry consortium engaged in educational and marketing activities in support of the VoiceXML (Voice eXtensible Markup Language) specifications and standards being developed by the W3C (World Wide Web Consortium). VXML will make the Web accessible and browsable via voice and audio (e.g., touchtone) commands. The VoiceXML Forum was established by AT&T, IBM, Lucent Technologies, and Motorola, and now includes a large number of industry members . www.voicexml.org. See also VXML.


Voice over Internet Protocol. The technology used to transmit voice conversations over a data network using the Internet Protocol. Such data network may be the Internet or a corporate Intranet. For much longer explanations, see VoFR, Voice over IP, VoIP Forum, Skype and Vonage.

VoIP Forum

Voice over Internet Protocol. The Voice over IP Forum was formed in 1996 by Cisco Systems, VocalTec, Dialogic, 3Com, Netspeak and others as a working group of the International Multimedia Teleconferencing Consortium (IMTC), which promotes the implementation of the ITU-T H.323 standard. The VoIP Forum is focused on extending the ITU-T standards to provide implementation recommendations as a means of supporting Voice over IP in order that devices of disparate manufacture can support voice communications over packet networks such as the Internet. By way of example, the VoIP Forum intends to establish directory services standards in order that Internet voice users can find each other. They also plan to port touch-tone signals to the Internet to allow the use of ACDs and voice mail systems. See also VON Coalition.


VolanoMark is a popular Java benchmark for measuring server throughput... it measures messages per second.

Volatile Storage

Computer storage that is erased when power is turned off. RAM is volatile storage.


An MCI term used to denote a volume of calls. Based on the words "Volume Serial." The term "Volser" can be applied to the manual collection of calls from a switch on a switch tape or through call data transmitted via NEMAS.


The unit of measurement of electromotive force. Voltage is always expressed as the potential difference in available energy between two points. One volt is the force required to produce a current of one ampere through a resistance or impedance of one ohm.

Volt Meter

An instrument for measuring voltages, resistance and current.


Electricity is a essentially a flow of electrons. They're pushed into a gadget ” toaster, computer, phone ” on one wire and they sucked out on the other wire. For this movement of electrons to occur there must be "pressure," just as there must be pressure in the flow of water. The pressure under which a flow of electrons moves through a gadget is called the electric voltage. Voltage doesn't indicate anything about quantity, just the pressure. The amount of electricity moving through a wire is called its current and is measured in amps. You figure the power in an electron flow (i.e. in electricity) by multiplying the flow's current by the voltage under which it flows.

Voltage Drop

The voltage differential across a component or conductor due to current flow through the resistance or impedance of the component or conductor.

Voltage Rating

The highest voltage that may be continuously applied to a conductor in conformance with standards or specifications.

Voltage Regulator

A circuit used for controlling and maintaining a voltage at a constant level.

Voltage Spike

An extremely high voltage increase on an electrical circuit that lasts only a fraction of a second, but can damage sensitive electronic equipment like telephone systems or can cause it to act "funny." If your phone system starts acting " funny ," one "cure" is to shut it off, count to ten, and then turn it on again. This sometimes clears the problem.

Voltage Standing Wave Ratio

VSWR. The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of mis-matched radio frequency transmission line.

Voltage Tuned Oscillator

VTO. The ratio of voltage to reflected voltage in a radio frequency device.


A device for measuring the difference of potential in volts .


  1. A volume is a partition or collection of partitions that have been formatted for use by a computer system. A Windows NT volume can be assigned a drive letter and used to organize directories and files. In NetWare a volume is a physical amount of hard disk storage space. Its size is specified during installation. NetWare v2.2 volumes, for example, are limited to 255MB and one hard disk, but one hard disk can contain several volumes. A NetWare volume is the highest level in the NetWare directory structure (on the same level as a DOS root directory). A NetWare file server supports up to 32 volumes. NetWare volumes can be subdivided into directories by network supervisors or by users who have been assigned the appropriate rights.

  2. Under ISO 9660, a single CD-Rom disc.

Volume Label

A name you can assign to a floppy or hard disk in MS-DOS. The name can be up to 11 characters in length. You can assign a label when you format a disk or, at a later time, using the LABEL command.

Volume Serial Number

A number assigned to a disk by MS-DOS. The FORMAT command creates the serial number on a disk.

Volume Unit

VU. The unit of measurement for electrical speech power in communications work. VUs are measured in decibels above 1 milliwatt. The measuring device is called a VU meter.


Abbreviation for VOLT-OHM-MILLIAMETER, probably the most common form of electronic test equipment. It measures voltage, resistance and current, and may have either a digital or analog meter readout. Some VOMs have other test functions such as audible continuity signals and special tests for semiconductors.


Voice over Multiservice Broadband Network. VoMBN is a means of supporting voice services (e.g., signaling services, and custom calling and Centrex services, as well as voice trunking) over DSL (Digital Subscriber Line) without the involvement of a Class 5 Central Office (CO) switch. VoMBN involves various signaling and processing servers and gateway devices at the network edge in support of VoIP (Voice over Internet Protocol) or VoATM (Voice over ATM) packet voice traffic presented to the network edge over a DSL local loop. VoMBN appeals to newer carriers that have built backbone networks based on either ATM or IP. Incumbent voice carriers generally prefer the approach of BLES (Broadband Loop Emulation Service), which accomplished much the same thing through an interface with a Class 5 switch based on traditional circuit-switching technology. See also BLES.

Vomit Comet

A plane used to simulate zero-G for astronaut flight training. Trainers often get motion sickness inside. Portuguese wine bottled in 1811 is called "comet wine." Its excellent quality is believed to be due to the Great Comet of that year. The term "comet wine" is often used for any wine made in the year of an important comet.


Voice On the Net (Internet), involving packetized voice. A recent development, initiating a VON call typically requires a multimedia PC or Mac computer with special software which matches that on the receiving device. More recently, Internet servers have been equipped with such software, although appropriate client (workstation) software must be installed to take advantage of this approach. More recently still, VON has been demonstrated from workstation to telephone, telephone to workstation, and telephone to telephone. Additionally, new compression techniques and new DSPs have dramatically improved the quality of VON transmission, mitigating the impacts of packet delay. See Internet Telephony for a detailed explanation. See also VON Coalition and Packetized Voice.

VON Coalition

The "Voice on the Net" (VON) Coalition is an Internet organization devoted to " educating consumers and the media by monitoring and supporting present and new developed telephony, video and audio technologies that are specifically designed and manufactured for the Internet community." It was formed, inter alia, to provide a forum against the ACTA (America's Carriers Telecommunications Association) petition to the FCC which sought to ban VON as a threat to the integrity of the PSTN and the concept of Universal Service. VON Coalition, www.von.org. See Universal Service Fund.


VOR (VHF Omnidirectional Range) collocated and/or combined with TACAN (Tactical Air Navigation Equipment).

Vote ACK

Also known as Mass ACK; in Usenet, the posting of the e-mail address of each person that voted for or against a newsgroup proposal.


A teleconferencing term. Also known as Polling. In a large, event-style teleconference, the participants can vote on an issue via the touchtone keypad. The teleconference service provider tabulates the electronic votes and advises the conference sponsor of the results.

Voting Receivers

A group of mobile base phone receivers operating on the same frequency as a control unit to pick the best signal from among them.


VMS OSI Transport Services. A Digital Equipment Corp. software product that modifies Digital's DECnet transport layer to conform to the International Standards Organization (ISO) Transport Protocol Class Four (TP4).


  1. Latin for "Voice." Some people put "Vox" on their business cards to distinguish their voice telephone number from their fax telephone number. It's a trifle pretentious.

  2. Voice Operated eXchange. Your voice starts it. When you stop speaking, it stops. Tape recorders use it to figure when to start recording and when to stop. There are pros and cons to VOX. With VOX you often miss the beginning of the conversation. And the tape goes on for 3 or 4 seconds after you've stopped talking. Also if ambient noise is high, VOX might mistake it for speaking and turn the recorder on and keep it running. Cellular phones also use VOX to save battery. A cellular phone without VOX is continuously transmitting a carrier back to the cell cite the entire time your call is in progress. The VOX operation used in smaller phones allows the phone to transmit only when you're actually talking. This reduces battery drain and enables handheld phones to operate longer on a smaller battery.


Voice Markup Language. See Voice Browser.


Voice over Wireless LAN (Local Area Network).


VOlume piXEL. The 3D equivalent of a pixel, or picture element. a voxel is the smallest distinguishable element of a three-dimensional (3D) image. The process of voxelization involves the stacking of slices, which are cross-sectional pixel images in two- dimensional format. In order that the underlying pixels are not obscured by darker , more opaque outside-layer pixels, the process also involves opacity transformation. Voxel images are used extensively in X-Rays, CAT (Computed Axial Tomography) Scans, and MRI (Magnetic Resonance Imaging) technologies. Voxel imaging also is used in some computer games . See also Pixel.


An early key system manufacturer, which made a combination 1A2 handsfree intercom telephone system. It was wood grained, inlaid into black plastic. An impressive phone system. Sadly, no more.


  1. Virtual Path. A SONET term for an end-to-end route between 2 points. Many Virtual Paths may share a common physical path. Each Virtual Path consists of Virtual Tributaries which, in turn, consist of Virtual Channels. In the ITU-T SDH terminology, a Virtual Path is known as a Virtual Container.

  2. An ATM term. Virtual Path is a unidirectional logical association or bundle of VCs, which are communications channels that provide for the sequential unidirectional transport of ATM cells .

  3. Velocity of Propagation. See Velocity of Propagation.


Voice Port Adaptor.


Voice Port Adaptor Rack.


An ATM term. Virtual Path Connection: A concatenation of VPLs (Virtual Path Links) between Virtual Path Terminators (VPTs). VPCs are unidirectional.


Virtual Private Data Network. A private data communications network built on public switching and transport facilities rather than dedicated leased facilities such as T1s.


Virtual Private Data Services. MCI's equivalent of Vnet for data.

VPDS 1.1

Virtual Private Data Service1.1. VPDS 1.1 provides Switched T1 and Switched T3 over a platform of Digital switch Corporation's ECS1 (DXC 3/1) and ECS3 (DXC 3/3) Cross-Connects, respectively. This is a switched data service and is intended for customers who do not want to pay a fixed price for private line services such as TDS1.5 and TDS45. VPDS 1.1 requires a customer to have dedicated access and egress, which is priced at a fixed rate. The network portion is priced on a usage basis and is the "switched" portion of the end-to-end circuit.


Virtual Path Identifier. An ATM term. Virtual Path Identifier is an eight- bit field in the ATM cell header which indicates the Virtual Path (VP) over which the cell should be routed. See VPI and VCI.


Voice Profile for Internet Messaging, a proposed Internet messaging protocol to allow disparate voice messaging systems to automatically exchange voice mail over the Internet. VPIM also will allow a voice messaging system to communicate with other such systems outside the organization. VPIM works like this: You record a message and enter the target telephone number of the intended recipient. Your voice processing system does a directory look-up to a public electronic directory, using LDAP (Lightweight Directory Access Protocol) to find the e-mail address assigned for voice messages for that individual. Your system converts the voice message to a MIME (Multipurpose Internet Mail Extension) attachment, and routes the message through the Internet using SMTP (Simple Mail Transfer Protocol). The message is delivered to the voice messaging system supporting the target telephone number, where it is converted back into a voice message and stored in the recipient's voice mail box. The recipient can respond in the same fashion. Now let's take it a step further. As the messages are converted to MIME attachments, and as it uses SMTP over the Internet, VPIM has the potential to support compound mail consisting perhaps of voice mail, audio mail, e-mail, and video mail. See also LDAP, MIME, SMTP, VPIM Work Group and www.ema.org/vpimdir/index.htm

VPIM Work Group

The goals of the Voice Profile for Internet Mail Work Group include establishing an internationally accepted standard profile of ESMTP/MIME to allow the interexchange of voice and fax messages between voice messaging systems; ensuring that this profile also allows interexchange with non-voice messaging MIME compatible email systems, establishing a directory service to support lookup of the routable address, and establishing a defined mapping specification with other voice messaging. The Group hosted a concept demo at EMA'96, a product demonstration at EMA'97, an info booth at CT Expo '98, and at the Fall 98 VMA Meeting in Athens. VPIM vendors are currently testing products for compatibility with the VPIM specification. The VPIM Specification, version 2 has been approved by the IETF as a Proposed Standard. After a long wait for its references to be published, VPIM v2 was published as RFC 2421 in September 1998. See also VPIM.


An ATM term. Virtual Path Link is a means of unidirectional transport of ATM cells between the point where a VPI value is assigned and the point where that value is translated or removed.


Virtual Private Network. There are several definitions for VPN, and we'll go through them in some detail. But first, we need to explain the overall concept. A VPN is not a private network, but is virtually so, which means it's almost so. That is to say that it exhibits at least some of the characteristics of a private network, even though it uses the resources of a public switched network. True private networks absolutely guarantee access to network resources, and security is perfect ” after all, the network is a private one, comprising dedicated leased lines. Those lines (or, more commonly today, the equivalent bandwidth) have been taken out of shared public use and dedicated to the private use of an end user organization on the basis of a lease arrangement. Those dedicated leased lines often go through various switching centers (e.g., COs or POPs), but go around, rather than through, the switches. As far as the private network is concerned , it's a wire center, rather than a switching center. The dedicated leased lines most commonly are T-carrier or even SONET in nature, directly interconnect two or more end user sites, and can be used for any purposes the end user desires. The end user can run any higher-layer protocol it chooses ” after all, it's a private network. Sounds great, doesn't it? Sure, it does, but the costs are high, and the complexities of designing and implementing such a network can be way out of proportion to the benefits. Virtual Private Networks don't exhibit exactly the same characteristics and, therefore, don't perform as well as true private networks, but can come pretty close...and at much lower cost. For example, a VPN might offer priority access to bandwidth and other network resources, whereas a true private network offers guaranteed access at all times. A VPN might offer relatively tight security mechanisms, whereas a private network is totally secure. Now, let's examine the specific definitions.

  1. The first VPN was developed for voice networking, but subsequently was developed for use in data networking, as well. Also known in AT&T terminology as a Software-Defined Network (SDN), these original VPNs remain in wide use on both a domestic and an international basis. Currently, they largely are used in support of voice, as Frame Relay and other packet network technologies have proved to be more effective in support of data applications. They are a public service offered by IXCs (IntereXchange Carriers) and making use of the circuit-switched PSTN (Public Switched Telephone Network). Originally known as Switched 56, the current usage of the term "VPN" distinguishes data services offered by AT&T, MCI (now Worldcom) and Sprint from Switched 56/64 Kbps services offered by the LECs (local phone companies). Although the specifics vary by IXC, VPNs offer bandwidth options of 56/64 Kbps, increments of 56/64 Kbps, 384 Kbps and 1.544 Mbps (T-1). The last two options are designed with videoconferencing in mind. VPNs provide transmission characteristics and services similar to those of private lines, including network testing, priority access, and security. Access to a circuit-switched VPN is provided over T-carrier (e.g., T-1 or Fractional T-1) local loops , which are full-duplex, four wire, digital circuits. As VPN services are dial-up services provided over the PSTN, they offer the same inherent any-to-any connectivity provided for voice calls, with the added feature of security through a Closed User Group (CUG). In other words, any location on your VPN can dial any other location on your VPN, but can't dial any number outside the CUG and can't be dialed by any number outside the CUG. VPNs also offer the advantage of the high level of PSTN redundancy, which translates into a high level of network resiliency. This network resiliency compares favorably to private, leased-line networks, which are highly susceptible to catastrophic failure. In fact, VPNs often are deployed as a backup to leased-line networks. VPNs also are extremely effective in support of enterprise data networking in organizations with large numbers of small sites. Small locations with relatively modest communications requirements often cannot be cost-effectively connected to long-haul, leased-line networks. VPNs offer the advantages of flexibility and scalability, as sites can be added or deleted relatively easily, with costs maintaining a fairly reasonable relationship to enterprise network functionality. The processes of network configuration (design) and reconfiguration are greatly simplified as compared to a leased-line network. Provisioning time is also greatly reduced, thanks to the flexibility of the circuit-switched network core ” the only dedicated portion of the VPN is the local loop, which is always dedicated, regardless of the network service accessed. Compared to a private network, the greatest disadvantage of VPNs is that all calls are priced based on a usage-sensitive algorithm much like that of a typical call over the PSTN. In other words, costs are calculated by duration and time of day, with prime-time calls being priced at a premium. Day-of-week and other special discounts also apply. Some carriers also consider distance in the pricing of VPN calls. Note, however, that the usage-sensitive costs of a VPN typically are a lot less than the cost-per-minute of a normal dial-up call over the PSTN, sensitive to factors including the number of sites connected, usage volume commitments, and contract length. Purely from a cost standpoint, leased- lines are preferred for networking large sites with intensive communications needs. Leased line networks also can support not only data and video transmission, but also voice, thereby offering the advantage of integration of all communications needs over a single network. Access to a VPN POP (Point of Presence) can be gained directly from the IXC (Inter- eXchange Carrier), from a CAP (Competitive Access Provider), or from the LEC (Local Exchange Carrier). Appropriate access technologies include leased lines, Switched 56/64, and ISDN. See also Switched 56 and Private Line.

  2. The second definition of VPN is a fairly generic one, referring to a packet data network service offering with some of the characteristics of a private network. Any packet data network can be used as the foundation for such a VPN, including X.25, TCP/IP, Frame Relay, and ATM networks. Each of these foundation networks is very different in terms of specifics, but they all are highly shared in terms of their basic nature. In order to provide services that emulate, or at least approximate, a private network over a highly shared network core, it is necessary to provide some additional features and mechanisms. One such feature is priority access to bandwidth, which can be accomplished through a variety of mechanisms which variously are intrinsic to the fundamental packet protocol (e.g., ATM) or through supplemental protocols (e.g., MPLS, or MultiProtocol Label Switching, which often is used in Frame Relay and TCP/IP networks). Security is a critical feature, which variously can be imposed through mechanisms such as a Closed User Group (e.g., Frame Relay) or tunneling (e.g., TCP/IP).

  3. In contemporary usage, VPN most commonly refers to an IP (Internet Protocol) VPN running over the public Internet. While the ubiquitous nature of the Internet is a huge advantage for data networking, the Internet is inherently both insecure and subject to variable levels of congestion. In order to create a VPN over the Internet, security issues are mitigated through the use of a combination of authentication, encryption, and tunneling. Authentication is a means of access control the confirms the identity of users through password protection or intelligent tokens, thereby reducing the possibility that unauthorized users might gain access to privileged internal computing or network resources. Authentication commonly is the responsibility of an access server running the RADIUS (Remote Access Dial-In User Service) protocol, connected to an access router with embedded firewall software. Encryption is the process of encoding, or scrambling , of the data pay- load prior to transmission in order to secure it; the decryption process depends on the receiver's possession of the correct key to unlock the safety mechanism. The key is known only to the transmitting and receiving devices. Tunneling is the process of encapsulating the encrypted payload in an IP packet for secure transmission. Tunneling protocols include SOCKv5, PPTP (Point-to-Point Tunneling Protocol), L2TP (Layer 2 Tunneling Protocol), and IPSec (IP Security).

The applications scenarios for IP VPNs include remote access, intranets, and extranets. Remote access VPNs are highly effective in support of telecommuters, mobile workers, and virtual employees. Intranets are used to link branch, regional, and corporate offices. Extranets link vendors, affiliates , distributors , agents, affiliates, and strategic partners into the main corporate office, with the level of access afforded being sensitive to the level of privilege indicated by a combination of password and user ID, as properly authenticated. This definition is courtesy of Ray Horak's excellent book, "Communications Systems and Networks." See also Authentication, Encryption, Extranet, Firewall, Internet, Intranet, IP VPN and Tunneling.


Very Plain Old Telephone Service. No automated switching.


Virtual Private Trunking. VPT - (as it pertains to VPN) - appears as a Frame Relay or ATM service to the enterprise, but uses VPN technology to deliver high-availability services, while enabling service providers to fully optimize trunk bandwidth. VPT accesses the flexible, high QoS capabilities of the Frame Relay and/or ATM services, and is suitable for both IP as well as non-IP requirements. For example, Switched Virtual Circuits (SVCs) could be used to link the various nodes in an Extranet, while Permanent Virtual Circuits (PVCs) could be used to link all the sites in an Intranet. PVCs provide as much security as a dedicated, circuit-based leased-line network. Enterprises concerned about using the Internet as their network backbone will find VPT's enhanced performance, QoS and security assuring. See VPN.


  1. Virtual Physical Unit.

  2. Voice Processing Unit.


Variable Quantizing Level. Speech-encoding technique that quantizes and encodes an analog voice conversation for transmission, nominally at 32 Kbps.


  1. Voice Recognition. See Voice Recognition

  2. Virtual Reality. See Virtual Reality.


Video RAM. Memory used to buffer an image and transfer it onto the display. It is a form of DRAM specially suited for video. VRAM differs from common DRAM in that it has two data paths ” a technique known as dual porting ” rather than the single path of traditional RAM; thus, it can move data in and out simultaneously. Two devices can access it at once. The CRT controller, which converts bits and bytes in video memory to pixels on the screen, and the CPU, which manipulates the contents of video memory, can access VRAM simultaneously . Conventional DRAM chips allow one read or write operation at a time. Video RAM supports simultaneous read/write, read/read and write/write operations. It's most often used in graphic accelerators. In video boards fitted with the less expensive DRAM, performance suffers somewhat because the CRT controller and the CPU must takes turns getting to the video buffer held in VRAM. See also DDR-SDRAM, DRAM, EDO RAM, Flash RAM, FRAM, Microprocessor, RAM, RDRAM, SDRAM, SRAM.


Vertical Redundancy Check. Synonymous with Parity Checking.


Virtual Ring Down.


A Novell NetWare program somewhat analogous to MS-DOS's CHKDSK program or Windows95's Scandisk. VREPAIR fixes FAT (File Allocation Table ) and DIR (Directory) Tables. It's a most useful program. Highly recommended.


Virtual Router IDentifier. An eight-bit identifier in the header of a VRRP (Virtual Router Redundancy Protocol) packet, the VRID identifies the virtual router for which the packet is reporting the status. See also VRRP.


Virtual Reality Modeling Language. A language for writing 3D HTML applications. VRML, according to PC Magazine, is an open standard for 3-D imaging on the World-Wide Web that paves the way for virtual reality on the Internet. The way VRML code describes a 3-D scene is analogous to four points describing a square, or a center point and radius describing a sphere. VRML viewers , similar to HTML Web browsers, interpret VRML data downloaded from the Web and render it on your computer. This allows the bulk of the processing to be performed locally and drastically reduces the volume of information that must be transmitted from the Web ” a key consideration if rendering is to be performed in real time. See VRML Consortium.


Virtual Route Pacing Response in SNA.


Virtual Router Redundancy Protocol. Specified in the IETF RFC 2338, VRRP is an election (i.e., optional) protocol that allows several first-hop virtual routers on a multiaccess LAN to dynamically share a single IPv4 (Internet Protocol version 4) address. One of the virtual routers, each of which actually may be in the physical form of a VPN (Virtual Private Network) concentrator, is designated as the Master, and the other as the Backup. Should the Master fail, the Backup automatically senses the failure, and assumes responsibility for forwarding LAN packets IP-addressed to it. As a dynamic and automatic approach to virtual router redundancy, VRRP offers considerable improvements in network resiliency as compared to running a dynamic routing protocol such as RIP (Routing Information Protocol) or OSPF (Open Shortest Path First), running an ICMP (Internet Control Message Protocol) discovery client, or using a route that is defined statically. Such dynamic routing protocols as RIP and OSPF, and running client discovery mechanisms through ICMP packets, commonly involve the active participation of all hosts on the network, which fact creates security issues and involves a good deal of administrative overhead, thereby lowering the effective throughput of the network. Statically configured default routes address these issues, but necessarily involve a single point of failure and, therefore, expose the network to catastrophic failure. This latter approach is commonly used in DHCP (Dynamic Host Configuration Protocol). VRRP addresses all of these issues, dynamically assigning first-hop router responsibility and providing redundancy and resiliency in the process, all without the excessive administrative overhead demanded of host-based router discovery protocols. All of that having been said, VRRP packets are sent periodically by the Master router to all VRRP routers, communicating the state of the Master. The VRRP packets are sent via encapsulation in IP packets, using the IP multicast address and the IP protocol number 112, as assigned by the IANA (Internet Assigned Numbers Authority). Note that there is a variation on the above theme, in which two virtual routers divide first-hop Master router responsibilities, with each serving as the Backup for the other. VRRP performs similar functions to several proprietary protocols, Cisco's HSRP (Hot Standby Router Protocol) and DEC's IP Standby Protocol. See also DHCP, HSRP, IANA, IETF, IPv4, OSPF, RIP, and VPN.


See Voice Board and Voice Response Unit.


  1. Virtual Scheduling. As an ATM term, it is a method to determine the conformance of an arriving cell. The virtual scheduling algorithm updates a Theoretical Arrival Time (TAT), which is the "nominal" arrival time of the cell assuming that the active source sends equally spaced cells. If the actual arrival time of a cell is not "too" early relative to the TAT, then the cell is conforming. Otherwise the cell is non-conforming.

  2. Virtual Source. Refer to VS/VD.

  3. See Virtual Storage.


Voice Store and Forward. Voice is digitally encoded, sent to large storage devices and later forwarded to the recipient. See Voice Mail.


Virtual Source/Virtual Destination. An ATM term, a VS/VD is an ABR connection may be divided into two or more separately controlled ABR segments. Each ABR control segment, except the first, is sourced by a virtual source. A virtual source implements the behavior of an ABR source endpoint. Backwards RM-cells received by a virtual source are removed from the connection. Each ABR control segment, except the last, is terminated by a virtual destination. A virtual destination assumes the behavior of an ABR destination endpoint. Forward RM-cells received by a virtual destination are turned around and not forwarded to the next segment of the connection.


Very Small Aperature Check.


Very Small Aperture Terminal. A relatively small satellite antenna, typically 1.5 to 3.0 meters in diameter, used for satellite-based point-to-multipoint data communications applications. While VSAT earth stations traditionally supported data rates of as much as 56 Kbps, contemporary systems can operate at rates of 1.544 Mbps. You see VSATs on top of retail stores which use them for transmitting the day's receipts and receiving instructions for sales, etc.

Consider the VSAT dishes you see on the roofs of gas stations. Large numbers of gas stations share access to a single satellite which, in turn, provides connection to a centralized data processing center. At those gas stations are intelligent gas pumps equipped with credit card readers, monitors , and limited computer memory. You swipe your credit card through the card reader, with the credit card number being transmitted through the VAST dish to the satellite to the data processing center. Once the credit is verified (i.e., the card has not been reported lost or stolen, and the balance is not overdue), the transaction is authorized in return. Once the desired amount of gas has been pumped, that information is transmitted to the data processing center, with the transaction being noted in the accounts receivable system for billing purposes. Additionally, the level of inventory (i.e., gas in the tank) is noted as having been decreased. In other words, the VSAT network supports credit verification, transaction authorization, billing and inventory management.


Vestigial Sideband. A form of Amplitude Modulation (AM) that compresses required bandwidth and is commonly used for video. VSB is modulation technique used to send data over a coaxial cable network. NTSC video standardizes a VSB technique. Another (16-level, digital) VSB technique has been chosen for HDTV systems and is under study for other digital video systems. VSB is also used by hybrid networks for upstream digital transmissions, VSB is faster than the more commonly used QPSK, but it's also more susceptible to noise. See also 64QAM, Amplitude Modulation, DSBSC, DSBTC, SSB, Vestigial Sideband and QPSK.


See Vertical Service Code.


  1. A British Term. Voice Services Equipment, a generic term for voice response unit, interactive voice response, voice processing unit and so on.

  2. Virtual Storage Extended.


  1. Vector Sum Exited Linear Prediction. A speech coding technique used in U.S. and proposed Japanese DMR standards. Second generation European DMR will probably use some version of VSELP.

  2. See Vector Sum Excited Predictive Coding.


Virtual Switch Interface.

VSI master

A VSI master process implementing the master side of the VSI protocol in a VSI controller. Sometimes the whole VSI controller might be referred to as a VSI Master but this is not strictly correct. A device that controls a VSI switch, for example, a VSI label switch controller.


Video Subscriber Line Access Multiplexer. A VSLAM is the device at the central office which enables VDSL ” Video DSL ” Video Digital Subscriber Line Service.


Virtual SS7 Network


Very Short Reach. A physical-layer specification for a parallel fiber optic connection operating at up to 10 Gbps over very short distances of 300 meters or less. The reason for VSR is twofold. First, lasers that work over short distances are far less expensive than lasers that work over longer distances. So VSR systems can be very cheap, since the laser's cost is a major part of the total cost of the system. Second, there are an enormous number of applications for VSR ” inside a central office, between one rack of equipment and another, between one router and another, etc. The VSR protocol uses an array of lasers typically firing at a wavelength of 850 nanometers, although any wavelength in the 830-860 nanometer range is acceptable. VSR makes use of VCSEL (Vertical-Cavity Surface-Emitting Lasers) lasers. Each VCSEL fires over a separate, parallel multimode fiber in a ribbon cable.

At the near end of the connection, the input data stream is inverse multiplexed, striped over multiple fibers in the VSR transmission system, and recombined at the far end of the connection. VSR is highly cost-effective for intraoffice connectivity over very short distances between devices (e.g., routers, optical cross-connects, and long-haul optical transport gear) collocated within a CO (Central Office) or POP (Point Of Presence). The combination of multiple relatively low-speed lasers and multimode optical fiber compare quite favorably to the cost of a single high-speed laser operating over a single monomode fiber and connecting to a single high-speed port. In either case, the aggregate bandwidth supported currently is 10 Gbps, or OC-192 in SONET terms. VSR is touted as scaling well, providing the foundation for more affordable intra-office interconnections at even higher speeds of 40 and 80 Gbps. See also Gigabit Ethernet, SONET, SR, and VCSEL.


Voice Server System.


Voltage Standing Wave Ratio. The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of mis-matched radio frequency transmission line. Explanation: When impedance mismatches exist, some of the energy transmitted through will be reflected back to the source. Different amounts of energy will be reflected back depending on the frequency of the energy. VSWR (Voltage Standing Wave Ratio) is a unitless ratio ranging from 1 to infinity, expressing the amount of reflected energy. A value of one indicates that all of the energy will pass through, while any higher value indicates that a portion of the energy will be reflected.


  1. Virtual Tributary. A SONET structure designed for transport and switching of subrate DS-3 payloads. VT1.5 equals 1.544 Mbps (T-1); VT2 equals 2.048 Mbps (E-1); VT3 equals 3.456 Mbps T-1c); and VT6 (T-2) equals 6.912 Mbps. See also SONET and Virtual Tributary.

  2. Virtual Tributary Group. A nine-row, 12-column structure (108 bytes) that carries one or more VTs of the same size. Seven VT groups can fit into one SRS-1 playload.

VT Pointer

Virtual Tributary Pointer. Locates the VT Synchronous Payload Envelope (VT SPE) for a floating mode Virtual Tributary (where the timing is not locked in frequency nor phase to the timing of the STS-1, but is allowed to float). See also SONET and Virtual Tributary.


VT Synchronous Payload Envelope.


Video Terminal 100. An incredibly capable CRT (Cathode Ray Terminal) developed by DEC in the early 1980s. The popularity of the VT 100 lead to its becoming an ad hoc standard, which still forms the basis for the xterm (X Terminal) terminal emulator programs for the X Windows system. VT102 is a newer version. See also Cathode Ray Tube and X Windows.


Virtual Tributary 1.5. A SONET term. A subrate channel with the payload equivalent of a T-1 frame at 1.544 Mbps. With SONET overhead, the total signaling rate is 1.728 Mbps. See also SONET, T-1, and Virtual Tributary.


Virtual Tributary 2. A SONET term. A subrate channel with the payload equivalent of an E-1 frame at 2.048 Mbps. With SONET overhead, the total signaling rate is 2.304 Mbps. See also E-1, SONET, and Virtual Tributary.


Virtual Tributary 3. A SONET term. A subrate channel with the payload equivalent of a T-1c frame at 3.152 Mbps. With SONET overhead, the total signaling rate is 3.456 Mbps. See also SONET, T-1c, and Virtual Tributary.


Virtual Tributary 6. A SONET term. A subrate channel of 6.912 Mbps with the pay- load equivalent of a T-2 at 6.312. With SONET overhead, the total signaling rate is 6.912 Mbps. See also SONET, T-2, and Virtual Tributary.


Virtual Trunk Agent.


Vermont Telecommunications Applications Center. See www.vtac.org


Virtual Telecommunications Access Method. A program component in an IBM computer which handles some of the communications processing tasks for an application program. In an IBM 370 or compatible, VTAM is a method to give users at remote terminals access to applications in the main computer. VTAM resides in the host. It performs addressing and path control functions in an SNA network that allows a terminal or an application to communicate with and transfer data to another application along some sort of transmission medium. VTAM also provides resource sharing, a technique for efficiently using a network to reduce transmission costs. See Systems Network Architecture.


Video TeleConference, a term invented by the U.S. Air Force.


Virtual Tributary Group


Vendor Technical Management.


Vendor Type Number.


Virtual Telecommunications Network Services.


Voltage Tuned Oscillator.


Voice Traffic (or Transport) over ATM.


Virtual Tributary Overhead.


Virtual Terminal Protocol. An International Standards Organization (ISO) standard for virtual terminal service.


Video To The Home. The general ability to provide interactive multimedia services to people in their homes .

VU Meter

VU is the unit of measurement for electrical speech power in communications work. VUs are measured in decibels above 1 milliwatt. The measuring device is called a VU meter, which is an abbreviation of volume-unit meter, a type of meter used to indicate average audio amplitude.


First came the CLI (Command-Line Interface). Then came the GUI (Graphical User Interface). Get ready for the VUI: the Video User Interface. Actually, you don't need to get ready for it any time soon, but you might start wondering how to use it.

Vulcan Nerve Pinch

The taxing hand positions required to reach all the appropriate keys for certain commands. For instance, the warm re-boot for a Mac II computer involves simultaneously pressing the Control Key, the Command key, the Return key and the Power On key. See also Three Finger Salute.

Vulnerability Assessment

See Intrusion Detection.

Vulnerability Scanner

A network vulnerability tester which sends data to various IP ports on a host to determine which ones are responsive ; vulnerability scanners can be used by hackers to find exploitable vulnerabilities or by security specialists to identify weaknesses needing to be strengthened .

Vulnerability Testing

I love this term. It sounds like some strange sexual perversion. In fact, it means nothing more than using tools and techniques to check how vulnerable your network is to being hacked, to being broken into, to being compromised. See also Network Penetration Testing.


VME Extension for Instrumentation. An extension of the standard VME bus design, VXI is intended for high-performance instrumentation applications such as test systems, laboratory automation systems, and industrial control systems. See also VME.


VXML is software designed to let you talk to the web sites, to have them answer you, i.e. give you the information you want ” from stock prices, to restaurant menus, to driving instructions, to sending and hearing emails. Voice Extensible Markup Language (Voice XML) is a Web-based markup language much like HTML (HyperText Markup Language) and XML, but designed for voice-based, rather than typing, graphical or textual interaction. Like HTML, VXML relies on HTTP (HyperText Transport Protocol) for TCP/IP transport. VXML supports telephone access to Web services, and supports Web browsing and Web-site interaction through voice and audio (e.g., touchtone and speech recognition), rather than traditional point-and-click mouse and keyboard commands. Once fully standardized and widely implemented, VXML will support four general applications categories, according to the VoiceXML Forum. Those are information retrieval, electronic commerce, telephony services (e.g., voice-activated dialing and conference calling, and one number, find-me services) and unified communications (i.e., unified messaging). The VoiceXML Forum develops the educational and marketing aspects of the VXML standard under development by the World Wide Web Consortium (W3C). At the time of this writing, VXML is in version 1.0, a specification from the VoiceXML Forum, which is being standardized by the W3C. Version 2.0, which is under development by the W3C, will feature the Speech Recognition Grammar Format (SRGF), an XML language for writing voice recognition gram- mer, and Synthesis Markup Language (SSML), an XML language for text-to-speech markup. See also HTML, HTTP, VoiceXML Forum, W3C, and XML.


VxWorks was developed by Wind River Systems and is a development and execution environment for real-time and embedded applications on a wide variety of target microprocessors (i.e. single chip computers).


A test used by Underwriters Laboratories to classify wires and cables by their resistance to burning. (Formerly designated as FR-1.)


Virtual Wavelength Path. A VWP is a group of one or more channels between source and destination nodes. The term virtual indicates that the signal path can actually travel on different physical wavelengths throughout the network. All channels of the VWP transit the same path through the network.


Vyvx is a division of Williams Communications and provides broadcast quality video transmission and advertising services to both television and internet broadcasters. When stations, networks, and internet companies want to get live video programming to their main broadcast facility in real-time, they either use their own satellite equipment or lease Vyvx lines. It has become common slang for any non- broadcaster owned transmission lines to be called Vyvx. Vyvx the company uses teleports, satellite trucks , or its vast network to transmit the video programming. Its services are used for the global distribution of news, sports and special events. Vyvx was the first company to provide switched, broadcast-quality fiber-optic transmission services for the broadcast television industry on a national scale in the early 1990s. Their network connects to every major news and media center in the US, to more than 100 professional sports venues in North America and to 450 television stations in the top 100 domestic markets.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133

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