Foreground Processing-FZA

Foreground Processing

Automatic execution of computer programs designed to preempt the use of the computing facilities. Usually a real time, urgent program. Contrast this with Background Processing, which might be something less urgent, for example, diagnostics of the system.

Foreign Address

An ATM term . An address that does not match any of a given node's summary addresses.

Foreign Agent

A Mobile IP term. A service which enables mobile nodes associated with nomadic users to register their presence at a remote location. The foreign agent communicates with the home agent in order that data packets can be forwarded to the remote subnet. See also Mobile IP.

Foreign Area Translation

Translating the office codes of a distant (foreign) area to codes that make sense to a PBX which has more than one way of completing the call to that area.

Foreign Central Office Service

Getting telephone service in a multi-office exchange from a central office other than the one you are normally served by. Not a common term any longer. Foreign central office service is the same price as normal local telephone service. It typically just involves asking for service off another central office. For example, our main number in New York City is 212-691-8215. Our 691- central office is in the 18th Street Exchange, a tall building on 18th Street. There is another central office in the same building. It is 206- and it is a more modern central office. When we ordered additional lines, we ordered them from this central office. You can now also call us on 212- 206-6660. Don't trust my definition, however. Ask your local telephone company. See also Foreign Exchange Service.

Foreign EMF

Any unwanted voltage on a telecommunications circuit.

Foreign Exchange Service

FX. Provides local telephone service from a central office which is outside (foreign to) the subscriber's exchange area. In its simplest form, a user picks up the phone in one city and receives a dial tone in the foreign city. He will also receive calls dialed to the phone in the foreign city. This means that people located in the foreign city can place a local call to get the user. The airlines use a lot of foreign exchange service. Many times, the seven digit local phone number for the airline you just called will be answered in another city, hundreds of miles away. See also Foreign Central Office Service and Foreign Exchange Trunk.

Foreign Exchange Trunk

A Foreign EXchange (FEX) trunk provides a direct connection between a PBX switch and a remote central office other than the central office that serves the location of the PBX.

Foreign Numbering Plan Area

FNPA. Any other NPA (Numbering Plan Area) outside the geographic NPA where the customer's number is located.

Foreign Prefix Service

Getting dial tone in a multi wire center exchange from a foreign wire center other than the one you are normally served by. Similar to Foreign Central Office Service, except that you may get charged extra for Foreign Prefix Service. Don't trust my definition, however. Ask your local telephone company. See also Foreign Central Office.


The Washington Post's Style Invitational asked readers to take any word from the dictionary, alter it by adding, subtracting or changing one letter, and supply a new definition. This one is one of the winners. Foreploy means any misrepresentation about yourself for the purpose of obtaining sex.


Foreign currency Exchange.


When you come to a fork in the road, take it. This profound piece of advice from the great American philosopher, Yogi Berra.


The splitting of an incoming call so that it rings at more than one telephone number. Whichever target telephone answers first establishes the connection, and the other telephone drops out of the equation.

Forklift Upgrades

A forklift is a self-propelled machine used to lift and transport heavy objects by means of steel fingers inserted under the load. An upgrade is an improvement or advancement in size or functionality. A forklift upgrade has its roots in the days of "heavy iron," when it literally took a forklift to upgrade the PBX or mainframe computer technology. One drove a forklift into the switchroom or computer room, picked up the system, transported it out the door, and brought in an improved system. The old system, which had little use, was made into a boat anchor or artificial reef, or so the story goes. Such upgrades typically cost an arm and a leg.

Such upgrades are increasingly uncommon today. Rather, much gear is upgradable by simply changing the generic software load, possibly inserting a card or microchip or two, and perhaps swapping out a power supply. Most switch manufacturers are trying to figure ways to avoid forcing their customers into forklift upgrades when their requirements outgrow the existing system. Examples include stackable hubs and distributed switches, which are scalable to one degree or another. See Scalable and Stackable .


A HTML formatted document containing blank fields that users can fill in with data. Fields include: text input, radio buttons , drop-down menus , and check-boxes. The process is usually completed by a Submit function, where the results are electronically entered into a database for further analysis. These are very common on the World Wide Web, where the form appears on the user's computer monitor, and can be filled in by selecting options with a pointing device, or typing in text directly from the computer keyboard.

Form 230

Form 730 Application Guide is a collection of literature you'll need to register your telephone/telecom equipment under Part 68 of Title 47 at the Federal Communications Commissions. To get this material (it's free) drop a line or call the Federal Communications Commission, Washington DC 20554. As I write this edition, the person at the FCC in charge is William H. Von Alven, who also puts out a newsletter for Part 68 applicants . See PART 68 for a much larger explanation.

Form Effectors

FEs. Control characters intended for the layout and format of data on an output device such as a printer or CRT. Examples are CR ( carriage return) and LF (line feed).

Form Factor

A fancy way of referring to the shape and size (width, depth, height) of some device like a computer, a telephone system, a circuit board, a processor or a computer chip.

Formal Call Centre

A British term. A telebusiness unit in which all of the staff are dedicated to telephone based work. See also Informal Call Centre.

Formal Standards

Specifications which are approved by vendor-independent standards bodies, such as ANSI (American National Standards Institute), ISO (International Standards Organization), IEEE (Institute of Electrical and Electronic Engineers ) and NIST (National Institute of Standards and Technology).


A point of excitation , or high energy, in a speech waveform caused by resonance in the human vocal tract . Formants are responsible for the unique timbre of each individual's voice.

Formant Synthesis

A form of synthesized speech in which the computer creates the voice. The result is smooth but sometimes artificial-sounding. Formant synthesis is used in text-to-speech (TTS) technology in which the computer "reads" text as voice. Another technology used in TTS is called concatenation synthesis, which uses actual samples of human voice, chopped up and put back together. Concatenation synthesis sounds choppy.


  1. Arrangement of bits or characters within a group , such as a word, message, or language.

  2. Shape, size and general makeup of a document. As a verb, its most common usage is in "to format this disk."

  3. As a verb in "to format." In the computing world, the common meaning of to format a hard disk is to completely clean the hard disk of old material so it will accept new material. Formatting a hard disk is typically done when it's new or when the disk has become so cluttered with bad files and junk that it's simply better to start all over again with a clean disk. There are typically two format commands. One is a quick format which simply destroys and rebuilds the file allocation table on the media, making it appear blank and unused to the computer's file system. But the material on the hard disk stays intact until overwritten by another file. Then there is a full format, also called low level format, which destroys and rebuilds the file allocation table and actually removes all trace of data on the media by overwriting it with all zeros. Full format takes longer. See also Computer Fingerprinting.


A cryptology mechanism developed by Mykotronx, Inc., a subsidiary of Rainbow Technologies, in conjunction with the NSA (the National Security Agency), which holds the registered trademark. The family of FORTEZZA security products includes PCMCIA- based client cards, and server boards ; compatible implementations are available variously in hardware and software. All FORTEZZA Crypto implementations support data privacy, user ID authentication, data integrity, non- repudiation , and timestamping. FORTEZZA is the crypto token chosen to secure the Defense Messaging System (DMS), including both the MILNET and the Internet. Applications include e-mail, voice communications and file transfer. Depending on the application, the encryption keys are either 80 or 160 bits in length, thereby providing excellent security for "Sensitive But Unclassified" (SBU) government data, as well as for commercial applications. FORTEZZA opponents suggest that the NSA is attempting to force the mechanism on the private sector as a replacement for the rejected Clipper Chip technology. The fear is that the NSA holds the keys to the secret encryption algorithm, and that the agency, therefore, can gain access to your data even more easily that it could have through the "backdoor" built into the Clipper Chip. See also Clipper Chip and MISSI.


FORmula TRANslation. A computer programming language developed in 1954 for scientific applications. It is still used by scientists and engineers.

Fortuitous Conductor

Any conductor that may provide an unintended path for intelligible signals, e.g., water pipes, wire or cable, metal structural members .

Fortune Cookie

  1. An inane/witty/profound comment that can be found around the Internet.

  2. The fortune cookie was invented in 1916 by George Jung, a German Los Angeles noodlemaker. Clearly it was a successful invention. He obviously used his noodle.


A section within an online service (such as CompuServe, America Online, etc.) where you can find out information on a specific subject ” computers made by Toshiba or printers made by Hewlett Packard. Forums may include a library from which you can download various files (programs, bug fixes, printer drivers, text, press releases of new products and so on). Many forums also include one or more "conference rooms" which users may "enter" for conversations (on-line or off-line) with representatives of companies or the person running the forum, who is typically called the "sysop," as in system operator. Most manufacturers run forums as a relatively cheap and painless way of getting help information to their customers.


A switch feature that temporarily redirects incoming calls. The incoming calls are redirected from the forwarding telephone to another destination by the person associated with the telephone or by the computing domain. The other destination has previously been defined to the switch by the device associated with the telephone.

Forward Busying

That feature of a telecommunications system wherein supervisory signals are forwarded in advance of address signals to seize assets of the system before attempting to establish a call.

Forward Channel

The communications path carrying data or voice from the person who made the call. The Forward Channel is the opposite of the Reverse Channel.

Forward Direction

  1. The forward direction of data away from the head-end in a broadband LAN.

  2. Forward link communications direction from a fixed earth station via a satellite to a mobile terminal.

Forward Disconnect

Disconnecting of a call path as a result on the called party hanging up. Prior to forward disconnect the called party could not initiate a disconnect of a call. This was the first denial of service attack, call someone that you don't like and then don't hang up and the call is never torn down and their phone is useless.

Forward Echo

An echo propagating in the same direction as the original wave in a transmission line, and formed by energy reflected back from one irregularity and then onward again by a second. Forward echoes can occur at all irregularities in a length of cable, and, when they add systematically, can impair its performance as a transmission medium.

Forward Error Correction

FEC. A technique of error detection and correction in which the transmitting host computer includes some number of redundant bits in the pay- load (data field) of a block or frame of data. The receiving device uses those bits to detect, isolate and correct any errors created in transmission. The idea of forward error correction is to avoid having to retransmit information which incurred errors in network transit. The additional bits add a small amount of overhead to the block or frame. Therefore, they create some level of inefficiency in transmission. The alternative is retransmission of the block or frame of data, which can be much more inefficient where large numbers of errors occur during transmission. This inefficiency is compounded when the retransmitted block or frame is errored, as well. From the standpoint of network throughput, FEC can be much more effective, particularly when bandwidth is expensive or limited. On the other hand, FEC is processor- intensive , as it places a load on the computational capabilities of the receiving computer. The simple idea of forward error correction is to avoid having to retransmit information sent incorrectly. The technique is consuming of bandwidth and can make the transmission take longer.

I asked Ray Horak, how can a few redundant bits of information significantly reduce error rates on transmission. Here's his reply: The process is extraordinarily complex. Explaining it would take pages and pages and would do no one but a mathematician any good. Essentially , a few redundant data bits are added at strategic places in the data field (for example, just suppose that every 50th bit were repeated ” the exact repeated bits vary according to the specific algorithm used). The very few redundant bits significantly lower the potential for an individual data bit to be transmitted in error and go undetected, given the complex sampling technique and complex algorithms used to develop a description of the data field. The receiving host computer is intelligent enough and has enough computational horsepower at its disposal to figure it out, unlike most of us real human types. The issue and the tradeoff is one of the cost of processing power vs. the cost of retransmission across the network. As the cost of computers comes down and the cost of bandwidth comes down, the best solution remains specific to the specifics of the user and the application.

Forward Prediction

A technique used in video compression, specifically compression techniques based on motion compensation, where a compressed frame of video is reconstructed by working with the differences between successive video frames .

Forwarding Description

An ATM term. The resolved mapping of an MPOA Target to a set of parameters used to set up an ATM connection on which to forward packets.


Formatting Output Specification Instance. An old SGML DTD standard for document management in the US military, replaced by the ISO standard DSSSL.


Fido/Opus/Seadog Standard Interface Layer. This is the interface used as an add-on to mailer software packages to connect them to PCs that are not 100% IBM-compatible.


Fiber Optic Test Procedure. Standards developed and published by the EIA (Electronics Industries Alliance) as EIA-RS-455.


Fiber Optic Transmission System. A generic term. SONET and SDH are the standards-based FOTS used by the carriers . See also SDH and SONET.

Foundation Graphics

A set of graphics libraries or imaging models that form the lowest level graphics programmer's interface in Sun's OpenWindows. Examples: a graphics sub-routine library that a program could call to draw graphics primitives like arcs, circles, rectangles, etc.

Four Horsemen of the Apocalypse

War, Plague, Famine and Death.

Four Pair UTP Cable

There are four pairs of conductors in this cable for a total of eight conductors. The cable jacket (also called the cable sheath) holds all four pairs together. Many manufacturers also include a ripcord, used for cutting the cable jacket. Pull on it, the sheath opens, allowing you to get to your conductors to attach them to things. Sometimes, the ripcord works. Sometimes, it doesn't. See UTP Cable.

Four Wave Mixing

See Four-Wave Mixing.

Four Wavelength Wave Division Multiplexing

4WL-WDM, also called Quad-WDM. MCI announced this technology in the Spring of 1996 as a method of allowing a single fiber to accommodate four light signals instead of one, by routing them at different wavelengths through the use of narrow- band wave division multiplexing equipment. The technology allowed MCI to transmit four times the amount of traffic along existing fiber. At that time MCI's backbone network operated at 2.5 Gbps (2.5 billion bits per second) over a single strand of fiber optic glass. Using Quad-WDM the same fiber's capacity rose to 10 gigabits ” enough capacity to carry approximately 130,000 simultaneous voice transmissions over one single strand of fiber. Since then, a number of carriers have deployed OC-192 (Optical Carrier Level 192) fiber, running at 10 Gbps. They are opening four " windows ," or wavelengths, each running at 10 Gbps. That's 40 Gbps over a single strand through DWDM (Dense Wavelength Division Multiplexing). They are pulling as many as 620 strands at a time. While most carriers have elected to implement WDM/DWDM in their networks by purchasing equipment from vendors, MCI has concentrated on developing their own WDM capability internally. Generally speaking, the intense competition among the various DWDM vendors is pushing capacity upwards faster than MCI's own internal development. See also WDM and DWDM.

Four-Wave Mixing

A source of noise in some fiber optic transmission systems, four-wave mixing is a phenomenon by which some wavelengths interact to create additional wavelengths. The problem occurs in the 1550nm (nanometer) window (wavelength band), which is the band in which DWDM (Dense Wavelength Division Multiplexing) and EDFAs (Erbium-Doped Fiber Amplifiers ) work. Non Zero Dispersion Shifted Fiber (NZDF), a type of Single Mode Fiber (SMF), addresses the problem by shifting the optimal dispersion point just above the range at which EDFAs operate . The optimal dispersion point is the point at which chromatic dispersion and waveguide dispersion cancel each out. See also Chromatic Dispersion, DSF, DWDM, EDFA, SMF, Waveguide Dispersion, and Wavelength.


See Four-wire Circuit.

Four-wire Adapter

A device which allows the connection of two-wire telephone equipment to a four-wire line. See Four-Wire Circuit.

Four-wire Circuit

A high-performance circuit, which offers lots of bandwidth and which is capable of multi-channel communications. Four-wire circuits are of two types: physical and logical. Physical four-wire was the original approach. In other words, they all comprised four wires, which were organized into two copper pairs of UTP (Unshielded Twisted Pair). These original four-wire circuits were analog, and used amplifiers to overcome the effects of signal attenuation, which is a significant problem at high frequencies. As the amplifiers worked in only one direction, two pairs of wires and two sets of amplifiers were needed: one for transmission in one direction and another in the reverse direction. A lot of physical four-wire circuits remain in use, and more are being deployed every day. Even though such circuits mostly are digital today, it generally still requires four physical UTP wires to provide four-wire service such as T-1.

Logical four-wire performs like physical four-wire, but with fewer wires. ISDN BRI (Basic Rate Interface) is an example of logical four-wire, as it usually uses only two wires to achieve relatively lots of bandwidth (144 Kbps), and multiple channels (2B+D, or 2 Bearer channels plus 1 Data channel). HDSL2 (High bit-rate Digital Subscriber Line, version 2), an emerging local loop technology, provides T-1 service over only 2 UTP wires. SONET fiber optic technology provides incredible amounts of bandwidth and supports hundreds of thousands of channels using only 2, or even 1, physical wires (glass fibers). Microwave, satellite and infrared transmission systems support four-wire service without any wires at all. See also ISDN, T-1 and SONET.

Four-wire Repeater

See Four-wire Circuit.

Four-wire Terminating Set

An electrical device which takes a four-wire circuit ” one pair coming and one pair going ” and turns it into the "normal" tip and ring circuit you need for a typical telephone, key system or PBX. See Four-Wire Circuit.

Fourier's Theorem

In the early 1800s, the French mathematician Emile Fourier proved that a repeating, time-varying function may be expressed as the sum of a (possibly infinite) series of sine and cosine waves. Digital data is a bit stream, which can be sent as a sequence of square waves. Fourier's Theorem shows that to send a square wave (digital signal), a series of sine waves (analog signals) are actually summed together. If 1,000 square waves are to be sent every second, for example, the frequency components of the sine waves that are summed together are 1 kHz, 3 kHz, 5 kHz, 7 kHz, etc. The point of this analysis is to show that high frequency signals are required to form a stable, recognizable square wave.

As the bit rate increases, the square wave frequency increases and the width of the square waves decrease. Thus, narrower square waves require sine waves of even higher frequencies to form the digital signal. Note, then, that there is insufficient bandwidth in the 3 kHz voiceband to send square waves due to the absence of frequency components above 3,300 Hz. Even low frequency square waves cannot be sent because sine waves below 300 Hz are also absent. Thus, the local loop, according to Fourier's Theorem, cannot be used for the transmission of digital signals! The last paragraph is, in fact, no longer totally correct, as the increasingly successful ISDN trials are proving.

Fourth Estate

The press. In May 1789, Louis XVI, King of France, summoned to Versailles a full meeting of the "Estates General." The First Estate consisted of 300 nobles; the Second Estate, 300 clergy; the Third Estate, 600 commoners. Some years later, and well after the French Revolution, Edmund Burke, looking up at the press gallery of the British House of Commons, said "Yonder sits the Fourth Estate, and they (i.e. the press) are more important than them all."

Fourth Utility

The non-vendor specific communications premise wiring system which you use for integrated information distribution (voice, data, video, etc.) Leviton in Bothell, Washington has trademarked the term Fourth Utility. They make a broad range of premise wiring products.

Fox Message

A standard sentence for testing teletypewriter circuits because it uses most of the letters on the keyboard. That sentence is "The quick brown fox jumped over the lazy sleeping dog, 1234567890".


  1. Feature Package. A software release for a telephone system. Originated with AT&T's Dimension PBX, now manufacturer discontinued.

  2. File Processor.


Flexible Printed Circuit.


Flat Panel Display.


Foreign Processor Data Link. A link from a Rockwell ACD to an external computer.


Feature Planning Guide.


See Field Programmable Gate Array.


Formal Public Identifier. A string expression that represents a public identifier for an object. FPI syntax is defined by ISO 9070.


Future Public Land Mobile Telecommunication System. A concept developed by the ITU for a family of technological solutions which would enable the development and implementation of a 3G (3rd Generation) wireless network in support of voice and high- speed data communications. FPLMTS was abandoned in favor of IMT-2000. See also IMT- 2000.


Fast Page Mode Dynamic Random Access Memory.


Fiber Optic Patch Panel.


  1. Fast Packet Switching.

  2. Frames Per Second. A measure of the quality of a video signal. NTSC TV ” the standard in North America ” uses 30 fps. Film is 24 FPS. PAL/SECAM (European) is 25 FPS.


Forced Perfect Terminator. A high-quality type of single-ended SCSI terminator, developed by IBM, with special circuitry that compensates not only for variations in terminator power but also for variations in bus impedance. See also Active Terminator and Passive Terminator.


Floating Point Unit. A formal term for the math coprocessors (also called numeric data processors, or NDPs) found in many PCs. The Intel 80387 is an example of an FPU. FPUs perform certain calculations faster than CPUs because they specialize in floating-point math, whereas CPUs are geared for integer math. Today, most FPUs are integrated with the CPU rather than sold separately. See also CPU and DSP.


Fully Qualified Domain Name. An Internet term. The FQDN is the full site name of an Internet computer system, rather than just its hostname. A fully qualified domain name consists of a host and domain name, including top-level domain. For example, is a fully qualified domain name where www is the host, jabber is the second-level domain, and .com is the top-level domain. A FQDN is used to locate a machine on a network.


See Flat Rate Service.


A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test. This designation has been replaced by VW-1.


Fixed Radio Access. Fixed radio access provides customers with a connection to a network via a radio link between their premises and a fixed antenna. Also known as WLL. See WLL.


A word coined in 1975 by Benoit B. Mandlebrot from the Latin "fractus," meaning "to break." Along with raster and vector graphics, fractals are a way of defining graphics in a computer. Fractal graphics translate the natural curves of an object into mathematical formulas, from which the image can later be constructed . One fractal creator called fractals a shape with the property of " self-similarity ." See also Fractal Compression.

Fractal Compression

An compression technique commonly used for color image files, fractal compression is well suited for images of natural objects. Fractal compression shrinks an image into extremely small resolution-independent files by storing it as a mathematical equation as opposed to storing it as pixels. The process starts with the identification of patterns within an image and results in a collection of shapes that resemble each other but that have different sizes and locations within an image. Each shape-pattern is summarized and reproduced by a formula that starts with the largest shape and repeatedly displaces and shrinks it. These patterns are stored as equations and the image is reconstructed by iterating the mathematical model. Depending on the specifics of the image file involved, fractal compression offers compression ratios as high as 100:1. As a result, it can store as many as 60,000 images on one CD-ROM. One disadvantage of fractal compression is that it is time consuming, taking as long as four minutes to convert a 1.3 MB TIFF file to a 228 KB file. As an asymmetric compression technique, however, it takes much less time to decompress the image than it does to compress it. As a lossy compression technique, it's not perfect ” some data is lost in the process. See also Fractal.

Fractal Geometry

The underlying mathematics behind fractal image compression, discovered by two Georgia Tech mathematicians, Michael Barneley and Alan Sloan.

Fractal Image Format

FIF. A compression technique that uses on-board ASIC chips to look for patterns. Exact matches are rare and the process works on finding close matches using a function known as an affine map.


Along with raster and vector graphics, fractals are a way of defining graphics in a computer. Fractal graphics translate the natural curves of an object into mathematical formulas, from which the image can later be constructed. See Fractal and Fractal Compression for a longer explanation.

Fractional Services

A British term. Bandwidth available from carriers in increments of 64Kbit/s such as Mercury's Switchband. See Fractional T-1 for the North American definition.

Fractional T-1

FT-1. Fractional T-1 refers to any data transmission rate between 56/64 Kbps (DSO rate) and 1.544 Mbps (T-1). Fractional T-1 is a four-wire (two copper pairs) digital circuit that's not as fast as a T-1. Fractional T-1 is popular because it's typically provided by a LEC (Local Exchange Carrier) or IXC (IntereXchange Carrier) at less cost than a full T-1, and in support of applications that don't require the level of bandwidth provided by a full T-1. While FT-1 is less costly than a full T-1, it is more costly on a channel- by-channel basis, as you would expect. Users love FT-1, but carriers hate it. FT-1 costs the carriers just as much to provision as does as full T-1, they just turn down some of the channels. FT-1 is typically used for LAN interconnection, videoconferencing, high-speed mainframe connection and computer imaging.

Fractional T-3

A telephone company service in which portions of a T-3 (44.7364 Mbps) transmission service are leased to provide a service similar to a T-1 (1.544 Mbps) or T-2 (3.152 Mbps) channel, but normally at a lower cost.


Frame Relay Access Device, also sometimes referred to as a Frame Relay Assembler/Disassembler. Analogous to a PAD (Packet Assembler/Disassembler) in the X.25 world, a FRAD is responsible for framing data with header and trailer information prior to presentation of the frame to a Frame Relay switch. On the receiving end of the communication, the FRAD serves to strip away the Frame Relay control information in order that the target device is presented with the data packaged in its original form. On the receiving end, the FRAD also generally is responsible for detecting errors in the payload data created during the process of network switching and transmission; error correction generally is accomplished through a process of retransmission. A FRAD may be a standalone device, although the function generally is embedded in a router. In a Voice over Frame Relay (VoFR) implementation, the VFRADs (Voice FRADs) also are responsible for compression and decompression processes. See also Frame Relay, VoFR, and X.25.


The term "fragging" was in widespread use during the Vietnam war and referred to the killing of officers by their own men using a fragmentation bomb such as a hand grenade.


The pieces of a frame left on an FDDI ring, caused by a station stripping a frame from the ring.


  1. In messaging it is the process in which an IP (Internet Protocol) datagram is broken into smaller pieces to fit the requirements of a given physical network. The reverse process is termed "reassembly."

  2. ATM and SMDS networks routinely perform a process of Segmentation and Reassembly (SAR), segmenting the native PDU into 48-octet payloads which are carried in 53-octet cells . The process is reversed on the receiving end.

  3. A condition that affects data stored on a disk. Adding and deleting records in a file, creates what is sometimes called the Swiss cheese effect. The operating system stores the data for an individual file in many different physical locations on the disk, leaving large holes between records. Fragmented files slow system performance because it takes time to locate all parts of a file.


Ferro-electric Random Access Memory. A type of RAM that uses very little power, FRAM also retains data when powered off. Typical applications include small devices such as PDAs, phones, and smart cards. See also DDR-SDRAM, DRAM, EDO RAM, Flash RAM, Microprocessor, RAM, RDRAM, SDRAM, SRAM, and VRAM.


  1. A frame is a packet. It's a generic term specific to a number of data communications protocols. A frame of data is a logical unit of data, which commonly is a fragment of a much larger set of data, such as a file of text or image information. As the larger file is prepared for transmission, it is fragmented into smaller data units. Each fragment of data is packaged into a frame format, which comprises a header, payload, and trailer. The header prepends (prepend means added to the front of) the payload and includes a beginning flag, or set of framing bits, which are used for purposes of both frame delineation (beginning of the frame) and synchronization of the receiving device with the speed of transmission across the transmission link. Also included in the header are control information (frame number), and address information (e.g., originating and terminating addresses). Following the header is the payload, which is the data unit (fragment) being transmitted. Appending the payload is the trailer, which comprises data bits used for error detection and correction, and a final set of framing bits, or ending flag, for purposes of frame delineation (ending of the frame). This frame format, in the broader generic sense, also is known as a data packet. Frame, therefore, is a term specific to certain bit-oriented data transmission protocols such as SDLC (Synchronous Data Link Control) and HDLC (High-level Data Link Control), with the latter being a generic derivative of SDLC. In the case of SDLC, a frame is very similar to a block, which would be employed in a character-oriented protocol such as IBM's BSC (Binary Synchronous Communications), also known as Bisync. See also BSC, HDLC, Packet, and SDLC.

  2. In TV video, a frame is a single, complete picture in video or film recording. A video frame consists of two interlaced fields of either 525 lines (NTSC) or 625 lines (PAL/SECAM), running at 30 frames per second (NTSC) or 25 frames per second (PAL/SEACAM). 24 frames are sent in moving picture films and a variable number, typically between 8 and 30, sent in videoconferencing systems, depending on the transmission bandwidth available. Up to about 12 frames a second looks "jerky."

  3. One complete cycle of events in time division multiplexing. The frame usually includes a sequence of time slots for the various sub channels as well as extra bits for control, calibration, etc. T-Carrier makes use of such a framing convention for packaging data. Channelized T-1, for instance, frames 24 time slots with a framing bit which precedes each set of sampled data.

  4. A unit of data in a Frame Relay environment. The frame includes a payload of variable length, plus header and trailer information specific to the operation of a Frame Relay network service.

  5. A metal framework, such as a relay rack, on which equipment is mounted. A distribution frame. A rectangular steel bar framework having "verticals and horizontals" which is used to place semipermanent wire cross connections to permanent equipment. Found in telephone rooms and central offices. See Distribution Frame.

Frame Alignment

The extent to which the frame of the receiving equipment is correctly phased (synchronized) with respect to that of the received signal.

Frame Alignment Errors

A frame alignment error occurs when a packet is received but not properly framed (that is, not a multiple of 8 bits).

Frame Alignment Sequence

See Frame Alignment Signal.

Frame Alignment Signal

FAS. Frame Alignment Signal or Frame Alignment Sequence.

The distinctive signal inserted in every frame or once in n frames that always occupies the same relative position within the frame and is used to establish and maintain frame alignment, i.e. synchronization. See Frame Alignment Errors.

Frame Buffer

A section of memory used to store an image to be displayed on screen as well as parts of the image that lie outside the limits of the display. Some systems have frame buffers that will hold several frames, in which case they should be called "frames buffers." But they're not.

Frame Check Sequence

Bits added to the end of a frame for error detection. Similar to a block check character (BCC). In bit-oriented protocols, a frame check sequence is a 16-bit field added to the end of a frame that contains transmission error-checking information. In a token ring LAN, the FCS is a 32-bit field which follows the data field in every token ring packet. This field contains a value which is calculated by the source computer. The receiving computer performs the same calculation. If the receiving computer's calculation does not match the result sent by the source computer, the packet is judged corrupt and discarded. An FCS calculation is made for each packet. This calculation is done by plugging the numbers (1's and 0's) from three fields in the packet (destination address, source address, and data) into a polynomial equation. The result is a 32-bit number (again 1's and 0's) that can be checked at the destination computer. This corruption detection method is accurate to one packet in 4 billion. See Frame Check Sequence Errors.

Frame Check Sequence Errors

Errors that occur when a packet is involved in a collision or a corrupted by noise.

Frame Dropping

The process of dropping video frames to accommodate the transmission speed available.

Frame Duration

The sum of all the unit time intervals of a frame. The time from the start of one frame until the start of the next frame.

Frame DS1

The DS1 frame comprises 193 bit positions . The first bit is the frame overhead bit, while the remaining 192 bits are available for data (payload) and are divided into 24 blocks (channels) of 8 bits each.

Frame Error

An invalid frame identified by the Frame Check Sum (FCS). See also Frame Errors.

Frame Error Rate

FER. The ratio of errored data frames to the total number of frames transmitted. If the FER gets too high, it might be worth while stepping down to slower baud rate. Otherwise, you would spend more time retransmitting bad frames than getting good ones through. In other words, throughput would suffer. The theory is that the faster the speed of data transmission the more likelihood of error. This is not always so. But if you are getting lots of errors, the first ” and easiest ” step is to drop the transmission speed. Frame Error Rate is thus a measure of transmission quality. It is generally shown as a negative exponent, (e.g., 10 to the minus 2 power (10^-2) means one out of 100 frames are in error.) The FER is directly related to the Bit Error Rate (BER). See also Bit Error Rate.

Frame Errors

In the 12-bit, D4 frame word, an error is counted when the 12-bit frame word received does not conform to the standard 12-bit frame word pattern.

Frame Flag Sequence

The unique bit pattern "01111110" used as the opening and closing delimiter for the link layer frames.

Frame Frequency

A video term. The number of times per second a frame is scanned.

Frame Grab

To capture a video frame and temporarily store it for later manipulation by a graphics input device.

Frame Grabber

A PC board used to capture and digitize a single frame of NTSC video and store it on a hard disk. Also known as Frame Storer. See Video Capture Board.

Frame Ground

FGD. Frame Ground is connected to the equipment chassis and thus provides a protective ground. Frame Ground is usually connected to an external ground such as the ground pin of an AC power plug.

Frame Header

Address information required for transmission of a packet across a communications link.

Frame Length

X.25 packets are fixed in length. ATM cells are fixed in length. Frame Relay frames (packets in the generic sense) are variable in length, which is due to their intended use for LAN internetworking. LAN frames (packets in the generic sense) are variable in length.

Frame Multiplexing

The process of handling traffic from multiple simultaneous inputs by sending the frames out one at a time in accordance with a specific set of rules. Instead of multiplexing traffic from a lower-speed connection into a higher speed connection based on a specific time duration for each low-speed channel, frame multiplexing using the length of a given frame as the measurement.

Frame Rate

The number of images displayed per second in a video or animation file. The Frame Rate is highly significant in determining the quality of the image, with a high frame rate creating the illusion of full fluidity of motion. 30 frames per second (30 fps) is considered to be full-motion, broadcast quality. On the other end of the scale, 2fps is most annoying. At 30 fps, the brain processes the images, filling in the blanks due to the "Phi Phenomenon." See PHI Phenomenon.

Frame Relay

Frame relay, technically speaking, is an access standard defined by the ITU-T in the I.122 recommendation, "Framework for Providing Additional Packet Mode Bearer Services." Frame relay services, as delivered by the telecommunications carriers, employ a form of packet switching analogous to a streamlined version of X.25 networks. The packets are in the form of "frames," which are variable in length, with the payload being anywhere between 0 and 4,096 octets. The key advantage to this approach is that a frame relay network can accommodate data packets of various sizes associated with virtually any native data protocol. In other words, a X.25 packet of 128 bytes or 256 bytes can be switched and transported over the network just as can an Ethernet frame of 1,500 bytes. The native Protocol Data Unit (PDU) is encapsulated in a Frame Relay frame, which involves header and trailer information specific to the operation of the Frame Relay network.

Further, a Frame Relay network is completely protocol independent. Not only can any set of data be accepted, switched and transported across the network, but the specific control data associated with the payload is undisturbed in the process of encapsulation. Additionally, and unlike an X.25 network, a Frame Relay network assumes no responsibility for protocol conversion; rather, such conversions are the responsibility of the user. While this may seem like a step down from X.25, the data neither require segmentation into fixed-length packets nor does the network have to undertake processor-intensive and time- consuming protocol conversion. The yield is faster and less expensive switching.

A Frame Relay network also assumes no responsibility for errors created in the processes of transport and switching. Rather, the user also must accept full responsibility for the detection and correction of such errors. The user also must accept responsibility for the detection of lost packets (frames), as well for the recovery of them through retransmission. Again, this may seem like a step down from X.25 networks, which correct for errors at each network node, and which detect and recover from lost packets. Once again, however, the yield is faster and less expensive switching. In fact, it is unlikely that frames will be damaged, as the switches and transmission facilities are fully digital and offer excellent error performance.

Much like X.25, Frame Relay employs the concept of a shared network. In other words, the network switches accept frames of data, buffer them as required, read the target address and forward them one-by-one as the next transmission link becomes available. In this fashion, the efficiency of transmission bandwidth is maximized, yielding much improved cost of service. The downside is that some level of congestion is ensured during times of peak usage. The level of congestion will vary from time-to-time and frame-to- frame, resulting in latency (delay) which is unpredictable and variable in length. This is especially true in a Frame Relay network, as the length of the frames is variable ” the switches never quite know what to expect.

Access to a Frame Relay is over a dedicated, digital circuit which typically is 56/64 Kbps, Nx56/64 Kbps, T-1 or T-3. The device which interfaces the user to the network is in the form of a Frame Relay Access Device (FRAD) which serves to encapsulate the native PDU before presenting it to the network. The FRAD at the destination address unframes the data before presenting it to the target device, with the two FRADs working together much as do PADs in a X.25 environment. Further, it generally is the responsibility of the FRAD to accomplish the error detection and correction process, although this responsibility may be that of the eventual target device. Across the digital local loop, the FRADs connect functionally to Frame Relay Network Devices (FRNDs, pronounced "friends"), proving once again that the carriers want to be your friends (especially as Frame Relay users tend to be large organizations with lots of $$$ to spend).

Frame Relay is intended for data communications applications, most especially LAN-to- LAN internetworking, which is bursty in nature. Frame Relay is very good at efficiently handling high-speed, bursty data over wide area networks. It offers lower costs and higher performance for those applications in contrast to the traditional point-to-point services (leased lines). Additionally, Frame Relay offers a highly cost-effective alternative to meshed private line networks. As the Frame Relay network is a shared, switched network, there is no need for dedicated private lines, although special-purpose local loops connect each customer location to a frame switch.

Frame Relay is a connection-oriented protocol, as transmission of frames between the user sites generally is on the basis of Permanent Virtual Circuits (PVCs), which are predetermined paths specifically defined in the Frame Relay routing logic. All frames transmitted between any two sites always follow the same PVC path, ensuring that the frames will not arrive out of sequence. Backup PVCs, generally offered by the carrier at trivial cost, provide redundancy and, therefore, network resiliency in the event of a catastrophic network failure. Switched Virtual Circuits (SVCs) are VCs selected on a call-by-call basis. SVCs are advantageous as they result in automatic load balancing, which improves overall service. As SVC logic is more costly, however, not all carriers offer it; those that do impose a surcharge on SVC users.

With Frame Relay, a pool of bandwidth is made instantly available to any of the concurrent data sessions sharing the access circuit whenever a burst of data occurs. An addressed frame is sent into the network, which in turn interprets the address and sends the information to its destination over broadband facilities. Those facilities may be as "slow" as 45 Mbps, but more often are SONET fiber optics in nature and operating at much higher speeds. Like traditional X.25 packet networks, frame relay networks use bandwidth only when there is traffic to send.

Frame Relay, while intended for data communications, also supports compressed and packetized voice and video. While such isochronous data is highly sensitive to the variable latency characteristic of packet networks, improved voice compression algorithms such as ACELP provide quite acceptable support for Voice over Frame Relay (VoFR), subject to the level of congestion in the network. For voice to be supported satisfactorily in a packet network, the receiving end compensates for delay and delay variation.

In addition to public network services, Frame Relay can also be implemented in a private network environment consisting of unchannelized T-Carrier circuits. Such an implementation offers exceptional data communications performance over an existing leased line network. Additionally, framed voice and video can ride over such a network, essentially for "free" when the circuits are not being used for data communications purposes. Thereby, the usage of the circuits is maximized, with little concern for poor quality due to network congestion.

A Frame Relay frame consists of a header, information field, and trailer. The header comprises a Flag denoting the beginning of the frame, and an Address Field used for routing of the frame, as well as for purposes of congestion notification. The Information Field is of variable length, from 0 to 4,096 Bytes. The trailer consists of a Frame Check Sequence (FCS) for detection and correction of errors in the Address Field, and an ending Flag denoting the end of the frame.

The American National Standards Institute (ANSI) describes frame relay service in the following documents:

ANSI T1.602 ” Telecommunications ” ISDN ” Data Link Layer Signaling Specification for Application at the User Network Interface.

ANSI T1.606 ” Frame Relaying Bearer Service ” Architectural Framework and Service Description.

ANSI T1S1/90 - 175 - Addendum to T1.606 - Frame Relaying Bearer Service ” Architectural Framework and Service Description.

T1.607-1990 ISDN Layer 3 Signaling Specification for Circuit-Switched Bearer Service for DSS-1.

T1.618 DSS-1 Core aspects of Frame Protocol for use with frame relay bearer service, ANSI, 1991.

ANSI T1.617a, Signaling specification for Frame Relay bearer service for DSS-1, 1994. Frame relay access makes use of the LAP-D signaling protocol developed for ISDN. Frame relay, technically speaking again, does not address the operation of the network switches, multiplexers or other elements. Both the ITU-T and ANSI were highly active in the development of Frame Relay standards, as was ETSI in Europe. See the next three definitions and also LAP-D, FRAD, FRND, PVC, SVC, VoFR, and X.25.

Frame Relay Access Device


Frame Relay Forum

The Frame Relay Forum is an organization of manufacturers, carriers, end users, and consultants committed to the implementation of Frame Relay in accordance with both national and international standards. The forum's technical committee begins with formal standards, from which it creates Implementation Agreements (IAs). IAs are formal agreements of all members with respect to the specific manner in which the standards will be applied, thereby helping to ensure interoperability of systems and networks. The forum began in 1990 as the Frame Relay Working Group, which was formed by the "Gang of Four," comprising Cisco, Digital Equipment Corporation, Nortel, and Stratacom (since acquired by Cisco). In 1991, the Frame Relay Forum was officially formed, and has grown to over 300 members. See also Frame Relay.

Frame Relay Implementors Forum

See Frame Relay Forum.

Frame Relay Modem

A data communications device which connects to a PC's COM (serial) port and emulates a dial tone while actually establishing a dedicated 56Kbps frame relay connection.

Frame Slip

That condition in a TDM network under which a receiver of a digital signal experiences starvation or overflow in its receive buffer due to a small difference in the speeds of clocks and the clock (transmission rate) at the transmitter. The receiver will drop or repeat of a full TDM frame (193 bits on a T-1 line) in order to maintain synchronization.

Frame Store

A system capable of storing complete frames of video information in digital form. This system is used for television standards conversion, computer applications incorporating graphics, video walls and video production and editing systems.

Frame Switch

A device similar to a bridge that forwards frames based on the frames' layer 2 address. Frame switches are generally of two basic forms, cut-through switch ( on-the-fly -switching) or store and forward switch. LAN switches such as Ethernet, Token Ring, and FDDI switches are all examples of frame switches.

Frame Synchronization

The process whereby a given digital channel (time slot) at the receiving end is aligned with the corresponding channel (time slot) of the transmitting end as it occurs in the received signal. Usually extra bits (frame synchronization bits) are inserted at regular intervals to indicate the beginning of a frame and for use in frame synchronization.

Frame UNI

Frame-based User-Network Interface, a frame format for access to ATM networks. Defined by the Frame Relay Forum, Frame UNI is a derivative of the DXI standard. For low-speed access application, it provides for a router to send frames (much like Frame Relay frames) to an ATM Edge Switch, where the conversion to cell format takes place.


A term used to describe a viewing and layout style of a World Wide Web site, it refers to the simultaneous loading of two or more web pages at the same time within the same screen. Originally developed by Netscape and implemented in their Navigator browser, today many other popular Web browsers support this feature. Some Web sites come in two versions; a "frames" and "no frames" version. The frames version usually takes a little longer to load and may contain other "enhanced" features such as Java and Animation. Frames are now falling into disrepute among web site designers and are being replaced with extensive use of tables, which are a much easier way to design web pages and also load a lot faster.

Frames Received OK

The number of frames received without error. See Frames Received Too Long.

Frames Too Long

An Ethernet statistic that indicates the number of frames that are longer than the maximum length of a proper Ethernet frame, but not as long as frames resulting from jabbering.


A Taligent definition. A set of prefabricated software building blocks that programmers can use, extend, or customize for specific computing solutions. With frameworks, software developers don't have to start from scratch each time they write an application. Frameworks are built from a collection of objects, so both the design and code of a framework may be reused.


An error control procedure with multiplexed digital channels, such as T-1, where bits are inserted so that the receiver can identify the time slots that are allocated to each subchannel. Framing bits may also carry alarm signals indicating specific alarms. In TDM reception, framing is the process of adjusting the timing of the receiver to coincide with that of the received framing signals. In video reception , the process of adjusting the timing of the receiving to coincide with the received video sync pulse. In facsimile the adjustment of the facsimile picture to a desired position in the direction of line progression.

Framing Bit

  1. A bit used for frame synchronization purposes. A bit at a specific interval in a bit stream used in determining the beginning or end of a frame. Framing bits are non-information-carrying bits used to make possible the separation of characters in a bit stream into lines, paragraphs, pages, channels etc. Framing in a digital signal is usually repetitive.

Framing Error

An error occurring when a receiver improperly interprets the set of bits within a frame.


The exclusive right to operate telephone service in a community. This right ” also called the franchise ” is granted by some government agency. Some phone companies existed before the appropriate regulatory authority, so they're "grandfathered" in their exclusivity. Some phone companies have an exclusive area to serve more because of their presence than because of the legal right conferred on them. The question of who has a franchise to serve what community with what service is becoming increasingly unclear as competition penetrates all aspects of the phone industry.

Franchise Authority

The franchise authority is the local body, usually a local government entity, that enters into a contractual agreement with a cable company. A franchise agreement defines the rights and responsibilities of each in the construction and operation of a cable system within a specified geographical area. The reason for the form agreement is that the cable company is typically a monopoly provider of cable TV. In return for grating that monopoly, the local government body typically extracts a "price" for granting that monopoly. It might be the existent of several community channels, available for free to the community or it may be free broadband circuits linking up the town's police, fire, schools and city offices.


Fire RetarDant. A rating used for cable within duPont's Teflon or equivalent fluor- polymer material. FRD cable is used when local fire codes call for low flame and low smoke cable. FRD cable is typically run in forced air plenums as an alternative to metal conduits .


A system for searching the international X.500 user directory.

Free Address Office

Office arrangement in which all personal spaces are eliminated in favor of employees picking up their supplies at a front desk upon arriving and then choosing a temporary work area each day.

Free On Board

FOB. Board. Term indicating where the seller's responsibility ends and the buyer's begins. You buy something, F.O.B. The seller puts it on a truck or railroad , plane, i.e. some carrier. He's responsible for getting it on the carrier. It's FOB, the truck. You ” the buyer ” are responsible for paying for the cost of the freight of getting you the goods you ordered. The term FOB is typically enhanced (or made clear), thus:

FOB Destination: Seller retains ownership until delivered to buyer. FOB Place of Delivery. Seller retains ownership until delivered to buyer. FOB Shipping Point. Seller responsibility ends when item is turned over to carrier. The buyer is responsible for payment if goods are damaged in transit. The buyer also handles any insurance claim.

The opposite of F.O.B. is C.I.F. That stands for Cost, Insurance and Freight are included. That means the seller pays the freight.

Free Range Workspaces

Office space available to anyone in the company on a first-come, first-served basis ” no registration required.

Free Space Communications

Any form of telecommunications that doesn't use a conductor (e.g., copper wire, or glass or plastic fiber). In other words, free space communications is accomplished using "space," rather than a conductor, as a medium. In simple terms, the system works through the air. Radio (e.g., radio, microwave, satellite, wireless LANs, cellular) and optical (i.e., infrared) transmission systems communicate through space, rather than through a conductor. See also Airwave and Free Space Loss.

Free Space Loss

This is simply the power loss of the signal as a result of the signal spreading out as it travels through space. As a wave travels , it spreads out its power over space, i.e. as the wave front spreads , so does its power. Sometimes called "spreading loss" to distinguish it from other losses which occur when radio waves pass through various gasses or material.

Free Space Optics

Free space optics is fancy way of saying that you send your telecom signal through the air using infrared (Ir) frequencies. Such transmission is line of sight. Free space optical systems typically run on the frequency of 785 nanometers at speeds of around 622 Mbps over distances of up to several miles, Free space optical systems are largely used to support local area network bridging where wired systems are not easily installed ” e.g. shooting from one side of the highway to the other, or across a lake. Systems now under development promise to run in the Gbps and even Tbps range, See also Infrared, Laser, and WLL.

Free Spectral Range

A measurement used to ensure components in optical systems such as connectors, splices, fiber ends and bulk optic interfaces do not reflect too much light back to the transmitter, causing the modulation characteristics and spectrum of the laser transmitter to change. Free spectral range is the period variation of the return loss of a device versus wavelength. See Return Loss.


Freedom is when the last kid graduates from college and the dog dies.

Freedom Link

Freedom Link is a type of cellular service that can be purchased by organizations to allow employees to communicate with one another via a closed-circuit system, similar to a wireless PBX. Nextel's Direct Connect is one such service.

Freedom of Mobile Multimedia Access



An organization to provide free Internet access to people in a certain area, usually through public libraries.


A service which permits the cost of the call to be charged to the called party, rather than the calling party. Freephone was pioneered in the US in 1966, where it is known generically as In-WATS (Incoming Wide Area Telecommunications Service), and makes use of the 800, 877 and 888 area codes, listed in order of introduction. Freephone service also is known as Greenphone or Freecall in some countries ; outside the US, the dialing prefix can be 0800, 0500, or some similar string of preceding digits.

Freephone has proven particularly popular with business subscribers, who are often willing to bear the cost of a telephone call in order to promote their services or to encourage customers to order their products by phone. Prior to the relatively recent approvals by the ITU-T of Recommendations E.169 and E.152, however, companies have been restricted to using their Freephone number in one country as the dialing patterns differ from country-to- country. Therefore, organizations wishing to offer products or services to customers on an international basis have had no choice but to register a separate International Toll Free Service (IFTS) number in each country, which has proved unwieldy and often inefficient. The new standard for Universal International Freephone Numbers (UIFNs) will encourage the development of international Freephone service through a standard dialing plan which can work across international borders. This will greatly free up companies' abilities to operate across international markets, benefiting consumers by allowing them to obtain information or to shop around for goods and services at no personal expense. It is hoped the new standard might also stimulate the market for Freephone services in Europe and Asia- Pacific, regions that until now have been slow to take up the service.

The potential market for the UIFN service is expected to be considerable. The globalization of markets via new technologies such as the Internet means that many companies are now able to offer their products and services to users in different countries, and will benefit from being able to advertise a single toll-free number to potential customers all over the world. Calls to the new global market number can also be routed to different destinations, allowing companies to direct their incoming calls to the most appropriate location for efficient handling. See also 800 Service, InWATS, International Toll Free Service, and Universal International Freephone Number.

Free Space Communications

Radio communications including microwave, satellite and cellular.


Software that doesn't cost anything, but may work just as well as the software you pay for.


  1. No more price hikes for three years. That a three year freeze on prices.

  2. In digital picture manipulators, the ability to stop or hold a frame of video so that the picture is frozen like a snapshot.

Freeze Frame

The transmission of discrete video picture frames at a data rate which is too slow to provide the perception of natural motion, referred to as "full-motion." An uncompressed, digitized full-motion video signal is typically transmitted at many millions of bits per second. Freeze frame can be carried on anything from a simple voice grade phone line running at 9.6 Kbps (the same speed as a Group 3 facsimile machine).

French Braid

A French braid shield is a type of shield used in coaxial cable systems comprising two serves (foil shields wound around the inner conductor) braided along one axis. It looks much like a French braid hairdo made of metal.

French, the

Regardless of what has been written, Napoleon Bonaparte was not short. For his time, he was of average height. Interestingly enough, he liked to surround himself with tall men, and he imposed a minimum height limit for recruits for the French Army. After the military disasters in Russia and at Waterloo, so many tall Frenchmen were killed that the genetic signature for tall- ness almost disappeared from France's gene pool. For well over the following century the average height of the French male was below that of the average European.


A term or abbreviation for a "file request" for a file from another node in a network. In FidoNet a node user usually freq's a file through mailer software which sends an appropriate request to a distant node that has the desired file. Freqing is the ability in FidoNet to transfer files back and forth between BBSs (bulletin board systems) automatically. Equivalent to file transfer in PCRelay.


Frequency defines number of events during a time period. Frequency is also the rate at which an electromagnetic waveform (e.g., electrical current) alternates, usually measured in Hertz (HZ). Hertz is a unit of measure which means "cycles per second." So, frequency equals the number of complete cycles of energy (e.g., current) occurring in one second. See Bandwidth, Frequency and Hertz.

Frequency Agile Modem

A modem used on some broadband LANs (Local Area Networks. A frequency agile model can search the frequencies on the LAN to find one available in order to communicate with other attached devices.

Frequency Agility

The ability of a cellular mobile telephone system to shift automatically between frequencies.

Frequency Band

The portion of the electromagnetic spectrum within a specified upper- and lower-frequency limit. Also known as Frequency Range. See also Band, Frequency for a complete list of all the frequencies.

Frequency Combiner

A diplexer or frequency splitter used backwards or in reverse.

Frequency Deviation

The extent to which an FM carrier moves from its center frequency during modulation.

Frequency Diversity

A way of protecting a radio signal by providing a second, continuously operating radio signal on a different frequency, which will assume the load when the regular channel fails. Here's another way of saying the same thing: Frequency diversity is a any method of diversity transmission and reception wherein the same information signal is transmitted and received simultaneously on two or more independently fading carrier frequencies.

Frequency Division Multiple Access

A technique for sharing a single transmission channel (such as a satellite transponder ) among two or more users by assigning each to an exclusive frequency band within the channel.

Frequency Division Multiplexing

FDM. An older technique in which the available transmission bandwidth of a circuit is divided by frequency into narrower bands, each used for a separate voice or data transmission channel. This means you can carry many conversations on one circuit.

Frequency Domain

Waveforms, such as speech signals, are typically viewed in the time domain, i.e. as power levels or voltages varying over time. The 19th century French mathematician Fourier demonstrated an algorithm called "Fast Fourier Transform", or FFT, which can express any complex waveform over a fixed interval as the sum of a series of sine waves of different energy levels. Analyzing signals in the frequency domain has proven an extremely powerful technique with diverse applications, including filtering, recognition and speech modeling.

Frequency Drift

The extent to which the unmodulated center frequency of an AM or FM carrier deviates from an FCC assigned frequency.

Frequency Frogging

The interchanging of the frequency allocations of carrier channels to prevent singing, reduce crosstalk, and to correct for a transmission line frequency-response slope. It is accomplished by having the modulators in a repeater translate a low-frequency group to a high-frequency group, and vice versa. Because of this frequency inversion process, a channel will appear in the low group for one repeater section and will then be translated to the high group for the next section. This results in nearly constant attenuation with frequency over two successive repeater sections, and eliminates the need for large slope equalization and adjustment. Also, singing and crosstalk are minimized because the high-level output of a repeater is at a different frequency from the low-level input to other repeaters.

Frequency Grease

A special kind of radio lubricant that is used to overcome problems of static in radio transmissions. Actually, there is no such thing, but every new radio technician falls prey to the joke. It's much like a "pot stretcher." Ray Horak, my Contributing Editor, was a Mess Sergeant in the US Army. He would send the privates on KP (Kitchen Patrol) to another mess hall to get a pot stretcher if the pot was too small, or to get a screen door for the refrigerator during the summer. His buddies in Communications would send the new radio technicians to get some radio grease. It was a lot of fun during the Vietnam War, which was not a lot of fun. It worked only one time per private (usually). See also Bucket o' Dial Tone.

Frequency Hopping

Another name for spread spectrum transmission. A technique developed by Hedy Lamarr, the actress, in the early part of the second world war to prevent the enemy from jamming or eavesdropping on conversations and on commands to steer torpedoes, etc. The idea is to hop from one frequency to another in split-second intervals as you transmit information. Attempts to jam the signal succeed only in knocking out a few small bits of it. So effective is the concept that it is now the principal antijamming device in the US military. Ms. Lamarr never got paid for the invention. But it was definitely hers. She invented it because of her patriotism for the United States. She had fled Austria in 1937. She received a U.S. patent in 1940.

Frequency hopping is used by cell phones for example to make it difficult to listen in to calls. The voice signal jumps around (hops) between frequencies in a given range at some set rate. This rate is, in theory, too rapid to tune in to before the next hop occurs. The range in which your piece of equipment operates, for example, is 2400-2438.5 MHz. These discrete ranges are assigned and controlled by the FCC so that things like your TV reception are not interfered with when the phone rings. A 20 db bandwidth implies that all the useful signal is contained in that area. In other words envision a standard bell shaped curve like that used in grading. Pretend there is a value on either side where the area under the curve is so small that you do not want to consider it and call those points the +20 db and -20 db points. The 20 db represents a ratio of signal that has become so weak so as not to be useful. If the distance from the +20 db point to the -20 db point exceeds 1 MHz then you are allowed to channel hop. With the caveat that at least 15 of the channels that you have designated as you hopping channels do not overlap. If they did, signal tracking is easier and interference becomes more probable. See also Frequency Hopping Spread Spectrum and Spread Spectrum.

Frequency Hopping Spread Spectrum

FHSS technology uses a narrow band carrier to broadcast packets that "hop" from frequency to frequency in a pattern synchronized between the transmitter and the receiver, thus maintaining a single logical channel. In an FHSS system, the total frequency band is divided into a number of fractional hop channels, spreading the broadcast traffic across the entire spectrum band, serving to reduce interference and to increase security. Complex algorithms determine the order in which data is sent and received. See also Frequency Hopping.

Frequency Modulation

A modulation technique in which the carrier frequency is shifted by an amount proportional to the value of the modulating signal. The amplitude of the carrier signals remains constant. The deviation of the carrier frequency determines the signal content of the message. Commercial TV and FM radio use this technique, which is much less sensitive to noise and interference than is amplitude modulation (AM). In the world of modems, digital bit streams can be transmitted over analog facilities through this same technique, whereby a 0 bit might be represented by a high-frequency sine wave (or set of sine waves) and a 1 bit by a low-frequency sine wave (or set of sine waves). Contrast with Amplitude Modulation and Phase Shift Keying.

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Frequency Offset

Non-linear distortion that causes a shift in the frequency of a received signal.

Frequency Response

The variation (dB) in relative strength between frequencies in a given frequency band, usually the voice frequency band of an analog telephone line.

Frequency Reuse

The ability to use the same frequencies repeatedly within a single system, made possible by the basic design approach used in cellular. Since each cell is designed to use radio frequencies only within its boundaries, the same frequencies can be reused in other cells not far away with little potential for interference. The reuse of frequencies is what allows a cellular system to handle a huge number of calls with a limited number of channels.

Frequency Shift Keying

FSK. A modulation technique for data transmission. See FSK for a full explanation.

Frequency Splitter

A device which separates an input band into two output bands. Devices with more than two outputs are also possible. A frequency splitter is a frequency combiner or diplexer used backwards or in reverse. It takes one band and divides it into two independent bands while suppressing alternate bands.

Frequency Standard

Generally a special receiver which receives synchronized signals transmitted by the National Bureau of Standards.

Frequency Tolerance

The maximum permissible departure by the center frequency of the band occupied by an emission from the assigned frequency or by the characteristic frequency of an emission from the reference frequency. By international agreement, frequency tolerance is expressed in parts per 10 (6) or in hertz. This includes both the initial setting tolerance and excursions related to short- and long-term instability and aging. In the United States, frequency tolerance is expressed in parts per 10(n), in hertz, or in percentages.

Frequency Translator

In a split broadband cable system, a frequency translator is an analog device at the headend that converts a block of inbound frequencies to a block of outbound frequencies.

Fresnel Loss

The loss at a joint that is caused by a portion of the light being reflected.

Fresnel Reflection

In optical physics, fresnel reflection is the reflection of a portion of incident light at a planar interface between two homogeneous media having different reflective indices. Fresnel reflection occurs at the air-glass interfaces at the entrance and exit ends of an optical fiber. Resultant transmission losses (on the order of 4 percent per interface) can be virtually eliminated by using antireflection coatings or index-matching materials. Fresnel reflection depends upon the index difference and the angle of incidence. In optical elements, a thin transparent film is sometimes used to give an additional Fresnel reflection that cancels the original one by interference. This is called an antireflection coating.

Fresnel Reflective Losses

For optical fiber communication, the losses incurred at the terminus interface that are due to refractive index differences. See previous definition.

Fresnel Region

In radio communications, the region between the near field of an antenna and the Fraunhofer region. The boundary between the two is generally considered to be at a radius equal to twice the square of antenna length divided by wavelength.

Fresnel Zone

Fresnel zone is the line-of-sight path between two microwave antennas. It is an elliptical zone between the two antennas where the total path distance varies by more than half of the operating wavelength. The concept is extended to describe the distance by which the direct wave clears any intervening obstacle such as a mountain peak. If the total path distance between transmitter, peak and receiver, is 1 wavelength greater than the direct distance, then the clearance is said to be two Fresnel zones.


Basically, there are two main standards regarding voice transmission over data networks: H.323 and "Voice Over Frame Relay Implementation Agreement" (FRF.11). Both specify that the following coders should be used: G.711, G.728, G.729, and G.723.1. The H.323 adds the G.722, and the VoFR (Voice over Frame Relay) adds the G.726/7 coders. The G.711 is a PCM coder that uses 64ks/s and two companding techniques: A-law and Mu-law. Recommendation G.722 describes 7 kHz audio-coding within 64 kbit/s. The G.723.1 describes a Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s and is based on Multi Pulse Maximum Likelihood Quantizer (MP-MLQ) (Voice frame duration of 30mSec). The G.726 describes 40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM). The G.727 describes 5-, 4-, 3- and 2-bits sample embedded adaptive differential pulse code modulation (ADPCM). The G.728 describes Coding of speech at 16 kbit/s using Low-Delay Code Excited Linear Prediction (LD CELP). The G.729 describes Coding of speech at 8 kbit/s using Conjugate-Structure Algebraic-Code- Excited Linear-Prediction (CS-ACELP) (Voice frame duration of 10mSec).


Multiprotocol Interconnect over Frame Relay.


Frame Relay Multicast Draft Service Description.


Frame Relay Network-to-Network Interface Implementation Agreement Draft.

Frictional Electricity

Static electricity produced by friction (e.g., by rubbing a hard rubber rod with a silk cloth.)


In the 19th century, the British Navy attempted to dispel the superstition that Friday is an unlucky day to embark on a ship. The keel of a new ship was laid on a Friday, she was christened HMS Friday, commanded by a Captain Friday, and finally went to sea on a Friday. Neither ship or crew were ever heard of again.

Friendly Name

A name, typically identifying a network user or a device, intended to be familiar, meaningful, and easily identifiable. A friendly name for a printer might indicate the printer's physical location (e.g. "Sales Department Printer").

Friesen, Gerry

One of the smartest people you'll meet in a long time. Gerry was, and remains my partner in most everything businessy I do. Originally, he was half the operation which published this dictionary (I was the other half). Now CMP Freeman publishes the dictionary, though I still write it. And Gerry has retired to his own personal paradise . On January 1, 1999 he sent me the following email: HAPPY NEW YEAR PARTNER!!! It's been a pleasure working with you over the years. I hope 1999 brings you everything you hope for. My New Year's resolution is to do something fun every day. Hope yours is as rewarding , whatever it is, as I plan mine to be."

Fringe Benefit

Generally this term refers to a reward received in addition to one's wage, such as a car, travel allowance, laptop computer. However this term can also refer to strips of toilet paper the ever-altruistic editor of this fine dictionary uses to bookmark reference material with and bestows upon lowly copy clerk, aspiring lexicographers visiting from Australia, such as the said Gavin Wedell.


Facility Restriction Level. A term created by AT&T for its Dimension PBX. These levels define the calling privileges associated with a line; for example, intragroup calling only in the warehouse, but unrestricted calling from the boardroom.


Frame Relay Network Device. Pronounced "friend." A device that sits at the edge of a public frame relay network. The FRND is the point of ingress into the cloud of the network on the inbound side of the network and the point of egress on the outbound side. The FRND connects to the user's FRAD (Frame Relay Access Device), which often is in the form of a router, over a digital access link, which usually is some form of T-carrier circuit (e.g., T-3, T-1, or Fractional T-1). A FRND can be in the form of either a switch or a router, although it usually is a router. See Frame Relay, FRAD and T-1.


  1. Frog means to switch pairs. e.g., there are two trunks connected to your PBX (trunks "A" and "B") Static is reported on trunk "B". A technician would "frog" the cable pairs to see if the problem was a PBX issue or a telephone company issue. If trunk "B" still has static when being connected to the PBX port that "A" was originally connected to, the problem would be isolated to the telephone company. If the static on trunk "B" goes away after being connected to the PBX port that trunk "A" was originally connected to, the problem would be the PBX and trunk "A" (which would now be connected to the PBX port that trunk "B" was originally connected to) would have static. Basically, it's a way of troubleshooting to see if the problem is a PBX problem or a telco problem.

  2. Regardless of what Budweiser would have you believe, frogs never drink. They absorb water from their surroundings by osmosis.


Frogging is the process of inverting line frequencies of a carrier system so that incoming high-frequency channels leave at low frequencies and vice versa. Frogging equalizes the transmission loss between high and low frequency channels.

Front-end Networking

Method for national and regional paging in which a network intercepts paging messages before they reach facilities of an RCC (Radio Common Carrier) or other conventional paging service provider. The network then routes messages to the appropriate transmitting facilities, either locally or in various distant locations.

Front-to-Back Ratio

A measure to compare the main lobe of an antenna in relation to the next strongest lobe of an antenna.

Front End

The client part of a client/server application that requests services across a network from a server, which is known sometimes as the back end. It typically provides an interactive interface to the user, for example, a data entry front end, allowing database to be entered into a database server. The term "front end" is, of course, a contradiction in terms. But, who said language had to be consistent, or logical? See back End, Front End Controller, Front End Development Tools and Front End Processor.

Front End Controller

See Front End Processor.

Front End Development Tools

These tools let a programmer control the design and manipulation of applications using visual techniques. Front-end development creates a graphical user interface, providing more flexibility and making it easier to link users with data accessed from database servers.

Front End Equipment

The equipment positioned between a computer and the communications line(s). Its purpose is to organize data being sent and received.

Front End Mailer

A program that operates on a bulletin board system and determines if a caller is another computer that wants to exchange mail or a human that wants to exchange mail or a human that wants to access the BBS resources. Usually the mailer transmits the prompt "Press ESC" and upon receiving an ESC character, or the passing of a timeout period, considers the caller to be human and gives it the resources of the BBS. Also known as a mailer.

Front End Processor

FEP. An FEP is a computer under the control of another, larger computer (typically a mainframe) in a network. The FEP does simple, basic "house- keeping" operations on the data streams as they arrive to be processed by the bigger computer. The FEP acts as a sort of intelligent traffic cop. It relieve the bigger, host computer of some of its telecommunications Input/Output burden, so that the host computer can concentrate on handling the processing burden . Depending on its sophistication, the front end processor might also perform serial to parallel conversion, protocol conversion, block or message assembly, etc. Here's a more technical definition: A dedicated communications system that intercepts and handles activity for the host. Can perform line control, message handling, code conversion, error control, and such applications functions as control and operation of special-purpose terminals. Designed to offload from the host computer all or most of its data communications functions. IBM 3705, 3725 and 3745 are Front End Processors. Front end processors are not used in client/server networks.

Front End Results

A call center/marketing term. Used to describe the rate of expected or tentative, rather than actual, orders generated, usually as a result of a trial or free offer.

Front Page Extensions

See FrontPage Extensions.

Front Porch

The blanking signal portion which lies between the end of the active picture information and the leading edge of horizontal sync.

Front Run

A prohibited practice whereby an employee of a stock brokerage firm, prior to executing a large customer order, places the same order for his/her personal account, thus "front running" the customer. The idea is that the customer's large order will push the price of the stock up, at which point the employee can sell his shares at a handsome profit.

Front Side Bus

See Frontside Bus.

FrontPage Extensions

Microsoft FrontPage Extensions is softare which runs on a computer attached to the Internet, i.e. a server acting as a web site. This software allows the "prepackaged functionality" of websites built in Microsoft FrontPage to run. In English this means that if you use Front Page to write your web site you can skip some complex coding if FrontPage extensions software is running on your web server. If you build a web- site using FrontPage, you (or your web site hosting company) will need to have FrontPage Extensions on the web server in order to properly display and process your web pages. Advanced web developers / webmasters do not use FrontPage because they choose to do this fancy server side programming themselves . This gives them greater control, security and flexibility. But it "costs." Most web sites don't run Windows which FrontPage extension must have to run. For the novice webmaster, according to Jim Koretz who worked on this definition, "You can't beat the built in functionality of FrontPage Extensions" Personally, I don't use FrontPage Extensions on either of my web sites ” or

Frontside Bus

Also known as the Memory Bus or System Bus, the Frontside Bus is the bus (i.e., common electrical path) within the microprocessor that connects the CPU (Central Processing Unit) of a PC with the main memory, the chipset, the L2 cache and other computer components. All data traverses the front side bus. See also Backside Bus.


Frame Reject.


  1. Frame-Relay Service: A connection oriented service that is capable of carrying up to 4096 bytes per frame. See Frame Relay.

  2. Family Radio Service. A very low-power, short-range two-way radio service in the 460 MHz band.

  3. Field Routing System.


Fixed Round-Trip Time: This is the sum of the fixed and propagation delays from the source to the furthest destination and back.


Field Replaceable or Replacement Unit.


Failed Signal.


Foreign Serving Arrangement.


Full Service Access Network. FSAN is a set of specifications for an APON (ATM- based Passive Optical Network) scheme developed by an international consortium of vendors, and ratified by the ITU-T within the G.983.1 standard (October 1998) . An FSAN network comprises three primary network elements: Optical Line Terminal, Optical Network Unit, and passive splitter. The Optical Line Terminal (OLT) is located in the carrier's Central Office (CO) or headend, where it serves to terminate the local loop that connects the subscriber premises to the edge of the network. The Optical Network Unit (ONU), also known as Optical Network Terminal (ONT), terminates the circuit 1) at the customer premises, 2) at the curb, or 3) at a centralized location in the neighborhood. The passive optical splitter sits in the local loop between the OLT and the ONUs. The splitter divides the downstream signal from the OLT at the network edge into multiple, identical signals that travel to the ONUs at the premises. Each ONU is responsible for figuring out which data are intended for it, and for ignoring all others. Upstream signals are supported by a time-division multiple access scheme, with the transmitters in the ONUs operating in burst mode. Current FSAN implementations run at speeds of 155/622 Mbps downstream over a wavelength running at approximately 1500nm (nanometers), and 155 Mbps upstream running at about 1310nm. FSAN trunk lengths can be up to 12 miles, and as many as 32 users and 64 endpoints can be supported per trunk at the current speeds and with the current splitter technologies. (Note: As a passive network, FSAN does not amplify the signal. Therefore, trunk lengths and signal splits are limited.) Encryption is built in for security. See also APON, FTTB, FTTC, FTTH, HFC, and PON.


Frequency Shift Keying. A modulation technique for transmitting data in digital format over an analog carrier, FSK involves shifting the frequency level of the carrier. There are two fairly common variations on the FSK theme. 2FSK (Two-level FSK) shifts the carrier signal between two frequencies, with one used to represent 1's and the other to represent 0's. 4FSK (Four-level FSK) shifts the carrier between four frequencies. HomeRF SWAP (Shared Access Wireless Protocol) specification provide for both modulation methods , with 2FSK supporting a maximum data of 0.8 Mbps and 4FSK supporting a maximum data rate of 1.6 Mbps. See also SWAP.


See Flexible Service Logic.


  1. Foreign Switching Office. Identifies the switching entity for WATS circuits when the customer is not being served out of its normal serving wire center.

  2. Free Space Optics. See Free Space Optics.


  1. File Service Protocol. FSP is a non-standard protocol that is similar to FTP (File Transfer Protocol). FSP is an application layer (Layer 7 of the OSI Reference Model) connectionless protocol that makes use of UDP (User Datagram Protocol) sockets, thereby placing the responsibility for error control on the receiving application program. While FSP is somewhat slower than FTP, it is a lightweight protocol that creates less of a system load than FTP. FSP is designed specifically for anonymous (i.e., no user name or password is required) file transfers, and does not require root access in order to install it on a system. FSP can run on a wide variety of platforms, including UNIX, Windows 95/NT/2000, OS/2, Macintosh, VMS, and MS-DOS. FSP originally was written for UNIX by Wen-King Su. See also Connectionless, FTP, ODP and OSI Reference Model.

  2. Fiber Optic Splice Panel.


See Free Spectral Range.


See Fixed Satellite System.


FSX is the same as a DSX except it is used for optical cross connects only. A DSX is a Digital System Cross-connect frame. It is a manual bay or panel to which T-1 lines and DS1 circuit packs are wired. It permits cross-connections by patch cords and plugs, i.e. by hand. A DSX panel is used in small office applications where only a few digital trunks are installed. See also DACS.


Fractional T-1. Any part of a T-1 circuit that's smaller than a full T-1 circuit. Fractional T-1 circuits are cheaper than full T-1 circuits. That's their reason for existing. See Fractional T-1 for a bigger explanation.


Fractional T-3. typically fractional T-3 delivers between four megabits per second, all the way to the full T-3 capacity of 45 megabits per second. Sometimes also Fiber T-3. See T-3.


Fractional T-1. See FT-1 and T-1.


Fractional T-3 or Fiber T3. See FT-3 and T-3.


File Transfer and Access Management. The OSI ( Open Systems Interconnection) standard for file transfer (i.e., the communication of an entire file between systems), file access (i.e, the ability to remotely access one or more records in a file) and management (e.g., the ability to create/delete, name/rename a file). FTAM is also an international standard.


Full Time Equivalent. A call center term. A scenario assumption used in budget forecasting and scheduling that defines the number of hours per week full-time employees are normally suppose to work. As a measure of staffing level, an FTE is equivalent to a full- time position, even though the hours may actually be filled by part-time schedules.


Fiber Transport Inside Plant.


  1. File Transfer Protocol. FTP lets users quickly transfer text and binary files to and from a distant or local PC, list directories, delete and rename files on the foreign machine, and perform wildcard transfers between machines. That distant or local PC (also called an FTP host) might be on your local area network, or a phone line across the world or connected to the Internet. It might also be your web site. I use FTP to transfer files to and from my various web sites, such as and Most versions of Windows come with elementary ftp software. Frankly, I prefer software called called WS_FTP Pro., which comes from a company called Ipswitch. See

    FTP is an application layer (Layer 7 of the OSI Reference Model) extension of the TCP/IP protocol suite, and was originally developed for transfers of large files of 50 KB (Kilobytes) or more. FTP is best known as an Internet tool for accessing file archives around the world that are linked to the Internet. If you have a modem with a terminal emulation program or are running Windows, you have all the software you need to visit ftp sites. Here's what it's like to visit the a ftp site. The site address may be Most public ftp sites accept anonymous login. That is, when the site asks who you are, you answer "anonymous." Then when they ask for your password, you give them your Internet email address. See also Anonymous FTP, FSP, OSI Reference Model, and TCP/IP.

  2. Foil Twisted Pair. A type of STP ( Shielded Twisted Pair) cable which is employed to protect the signal-carrying conductors from EMI (ElectroMagnetic Interference). FTP uses a thin metallic foil; ScTP (Screened Twisted Pair) uses a heavy braided mesh for this purpose. See also STP.

  3. Financial Transaction Processing. A Wall Street term.

FTP Mail Server

A server which permits the retrieval of files via e-mail. See FTP.


Federal Telecommunications System is a private telephone network sometimes shared enthusiastically by all federal government agencies. And sometimes not. See FTS2000.


The U.S. General Services Administration in Washington, D.C. describes the FTS2000 as "the state of the art, digital, long distance telecommunications program that provides voice, data and video transmission services to federal government agencies."


Fiber To The Building. See FTTC, FTTN, FTTP and HFC.


Fiber To The Curb. A hybrid transmission system which involves fiber optics to the curb, and either twisted pair or coaxial cable to the premises. FTTC is less extreme than FTTH, but more so than FTTN. See also FTTH, FTTN and HFC.


Fiber To The Cabinet. Also known as FTTN (Fiber To The Neighborhood). A Hybrid Fiber Coax (HFC) network architecture involving an optical fiber which terminates in either a street-side or neighborhood cabinet which converts the signal from optical to electrical. The subscriber connection is over either UTP (Unshielded Twisted Pair) or coaxial cable. FTTCab can be either FTTC or FTTN. See HFC.


Fiber to the Home. The fiber deployment architecture in which optical fiber is carried all the way to the customer's home (or premises). This is the ideal architecture and also the most costly to implement. See FTTN and FTTP.


Fiber To The Neighborhood. Also known as FTTCab (Fiber To The Cabinet). A hybrid network architecture involving optical fiber from the carrier network, terminating in a neighborhood cabinet which converts the signal from optical to electrical. The connection from the cabinet to the user premises is over UTP (Unshielded Twisted Pair) or coaxial cable. ILECs (Incumbent Local Exchange Carriers), i.e., local telephone companies, use the embedded UTP for this purpose; CATV providers use the embedded coaxial cable. The advantages of the fiber include incredible levels of bandwidth, outstanding error performance, and transmission over long distances without the requirement for expensive and troublesome repeaters. The advantage of the UTP and coax is simply it is already there. The advantage of the neighborhood cabinet is that the expensive optoelectric conversion process takes place at a single location per neighborhood of perhaps 100 or 200 users. The cabinet also serves as a sophisticated multiplexer, allowing all the users to share the single, high-capacity fiber optic system for connection to the carrier network. FTTN is the preferred local loop architecture in a full convergence scenario, which involves the delivery of voice, Internet access, and entertainment TV over the same hybrid cable plant. While FTTH (Fiber To The House) is preferable in terms of overall performance, it currently is too expensive for serious consideration. Further, ADSL (Asymmetric Digital Subscriber Line) technologies will support the necessary levels of bandwidth over considerable distances, assuming the UTP is of good quality. See also ADSL, Fiber Optics, FTTH, FTTN, FTTP, HFC and SONET.


Fiber To The Premise. Also know as FTTB (Fiber To The Building) and FTTH (Fiber To The House). FTTP is the most extreme implementation of fiber optic transmission systems. FTTP literally involves a fiber optic system which connects directly from the carrier network to the user premises. The advantages of the fiber include incredible levels of bandwidth, outstanding error performance, and transmission over long distances without the requirement for expensive and troublesome repeaters. Taking the fiber optic transmission system to the premise extends all of these advantages to the user's front door. FTTP is used extensively by CAPs (Competitive Access Providers) and CLECs (Competitive Local Exchange Carriers). It also is used increasingly by ILECs (Incumbent LECs) and IXCs (IntereXchange Carriers) to provide the optimum level of service to medium and large businesses, which can make full use of the unparalleled performance of the fiber local loop. FTTP also was highly touted as the ultimate solution for residential application (FTTH) in a full convergence scenario. Full convergence involves the support of voice, Internet access, high-speed data communications, entertainment TV, videoconferencing, and other forms of communications-all over a single local loop. While FTTH certainly is attractive, it's just too expensive at the moment. FTTN (Fiber To The Neighborhood) is a much more cost-effective approach. See also FTTN.

Fu Fu Dust

See Foo Foo Dust.


See FBU.


F...d Up Beyond All Recognition. In short, a mess. A term often used in electronic mail messages. See also BOHICA, SNAFU and TARFU.


Fear, Uncertainty, Doubt. A marketing tactic which a dominant player (once IBM) has used to discourage its customers from buying from its competitors .

Fugitive Glue

Glue used by printers to affix stuff into magazines. The glue is designed to stick until the magazine is delivered. At that point, the stuck-in thing becomes easier to remove and/or falls into your lap. This definition contributed by Rich Kubik.

Fugitive Odor

A smell that leaks out of a composting plant or landfill.

Full Availability

Idealized condition which exists when your phone system can provide connections for every telephone connected to it. Also called Non-Blocking.

Full Duplex

FDX. A transmission mode which supports transmission in two directions simultaneously, or, more technically, bidirectional, simultaneous two-way communications. Simplex mode supports transmission in one direction, only. Half-duplex (HDX) mode supports transmission in both directions, but in only one direction at a time. The best two-direction phone conversations take place on four-wire circuits, which traditionally are physical four-wire. That is to say that there are four physical wires, with two (i.e., one pair) for transmission in one direction and two (i.e., one pair) for transmission in the other. (Note: There also are logical four-wire circuits, which comprise two wires, or even one wire, but which behave as though there were four wires.) All long distance circuits are four-wire ” they have to be in order to support multichannel communications and, thereby, to haul large numbers of separate conversations. Most local loops are two wire, which also can support full-duplex communications, but for only one conversation at a time. It's important to contrast full duplex with symmetrical, or symmetric, and asymmetrical, or asymmetric. Again, full duplex means simultaneous transmission in both directions. Asymmetric means more bandwidth (or speed) in one direction than in the other. Symmetric means the same bandwidth (or speed) in both directions. For example, V.90 (56 Kbps) modems operate in full-duplex mode on an asymmetrical basis, while older V.34 (28.8 Kbps and 33.6 Kbps) modems operate in full-duplex mode on a symmetrical basis. T-1 operates in full- duplex mode on an asymmetric basis, as does ISDN. All DSL (Digital Subscriber Line) technologies run in full-duplex mode, and most (e.g., ADSL and G.lite) operate on an asymmetrical basis. Most speakerphones (except the newer more expensive ones, and the really old toadstool-looking ones made by Western Electric) are half-duplex, meaning they only transmit in one direction at one time. The speakerphone flips its direction based on who's talking, or, more precisely, who's talking the loudest. Full duplex speakerphones are the best. See ADSL, Asymmetric, DSL, Four-Wire, Half-Duplex, Simplex, Speakerphones, Symmetric, T-1, Two-Wire, V.34, and V.90.

Full Duplex Audio

Audio that allows remote sites to speak simultaneously without losing audio contact (two-way simultaneous audio). See Full Duplex.

Full Duplex Transmission

The process of operating a circuit so that each end can transmit and receive simultaneously. See Full Duplex for bigger explanation.

Full Echo Suppressor

An echo suppressor in which the speech signals on each path are used to control the suppression loss in the other path of a 4-wire circuit. Used for long-distance communications. Compare with split echo compressor.

Full Mesh

Term describing a network in which devices are organized in a mesh topology, with each network node having either a physical circuit or a virtual circuit connecting it to every other network node. A full mesh provides a great deal of redundancy but because it can be prohibitively expensive to implement, it usually is reserved for network backbones. See also Mesh.

Full Motion Video

Television transmission where images are sent and displayed in real-time and motion is continuous. Video reproduction at 30 frames per second (NTSC- original signals) or 25 frames per second. (PAL-original signals). Compare with freeze frame. See Freeze Frame Video.

Full Name

What you call your child when you're mad at him.

Full Period

In private line telephone and telegraph service, a circuit rented for the exclusive use of a single customer on a month-by-month basis. Archaic in the sense that part-time circuits have not been rented for years.

Full Service

When a pager screen reads Full Service, this indicates you are in prime coverage range and will receive all new messages as well as any undelivered, stored messages.

Full Service Access Network


Full System Battery Backup

This means there's sufficient battery power backing the phone system so that during a power outage , the telephone system will continue to work, i.e. you won't even know the commercial power has gone out. All programming will be intact. Calls will get through, etc. Full System Battery Backup is critical to many businesses, especially those in the "life or death" business, such as hospitals , police, fire departments, etc. Other businesses who depend heavily on the phone for their revenues ” airlines, brokerage companies, hotel/motels, etc. ” often also use full system battery backup.

Full Time Equivalent

FTE. A call center term. A scenario assumption used in budget forecasting and scheduling that defines the number of hours per week full-time employees are normally suppose to work. As a measure of staffing level, an FTE is equivalent to a full-time position, even though the hours may actually be filled by part-time schedules.

Fully Connected Network

A network topology in which each node is directly connected by branches to all other nodes. This architecture becomes impractical as the number of nodes in the network increases in complexity. Such networks normally go to distributed nodes.

Fully Perforated

Paper tape on which information is represented by the holes punched through the paper.

Fully Qualified Domain Name

FQDN. In Internet terms, the full name of a system, rather than just a host name. For example, if the host name is Harry, the full name is harry

Fully Restricted Stations

In a PBX, fully restricted stations (also called phones) can't place any outside calls. They can make intercom calls as well as receive incoming calls.


What a cell site does when it drops your call.


What it does. The action carried out by a piece of equipment or software program. See also Feature.

Function Key

  1. One of up to 12 keys on a PC keyboard labeled with the letter F followed by a number. The effect (if any) of pressing a particular function key depends on which program you are running at the time.

  2. An undefined key on a computer or telephone that can be defined to perform one function, which would normally require the user hitting one or several keys in succession.

Functional Entity

FE. A set of functions that provides one or more specified capabilities. Seven FEs have been identified for the Advanced Intelligent Network Release 1 architecture: Network Access, Service Switching, Service Logic and Control, Information Management, Service Assistance, Automatic Message Accounting and Operations. Definition from Bellcore in reference to its concept of the Advanced Intelligent Network. See AIN.

Functional Group

A collection of FEs (Functional Entities) that reside together in a system.

Functional Management Layer

A communications layer in SNA that formats presentations.

Functional Profile

A defined stack of ISO OSI-Layer elements, such as GOSIP, MAP or TOP. Functional profiles were developed in order to ensure that, when defined, ISO OSL stacks could interoperate . Due to the number of different protocol elements at each OSI layer, it was possible to define stacks that were syntactically correct, but would not be able to exchange information due to differences at particular layers . A functional profile that has been defined as a standard is termed a standardized profile. Likewise, an International Standard Profile is an ISO OSI functional profile.

Functional Resource

An abstraction of physical entities (e.g., voice synthesizers) that the Service Assistance FE (Functional Entities) can manipulate.

Functional Signaling

In an ISDN circuit, function signaling provides messages with unambiguous, defined meanings known to both the sender and receiver of the messages. Signaling is generated by the terminal.

Functional Specification

A description of a system from a working point of view. It differs from a precise technical description which includes each piece of equipment precisely spelled out. A system can often work the same using different hardware and software configurations. By functionally describing a system, a user allows sellers to use their imagination to solve the problem in the most creative, cost-effective way. Most sellers prefer functional descriptions.

Functional Split

A division within an automatic call distributor (ACD) which allows incoming calls to be directed from a specific group of trunks to a specific group of agents .

Functional Test

A test carried out under normal working conditions to verify that a circuit or particular part of the equipment works properly.

Functional Transparency

The ability of a network to carry any user information regardless of its form, so that user applications can operate through the network.

Functional User

An entity external to the functional architecture that uses the functional architecture capabilities to exchange information with other functional users. Definition from Bellcore in reference to its concept of the Advanced Intelligent Network.


The reason many people showed up at Louis B. Mayer's funeral was because they wanted to make sure he was dead. This quote was from Samuel Goldwyn, film producer. See Goldwyn, Samuel.


Frame-based User-Network Interface, a frame format for access to ATM networks, very much like Frame Relay but with a few additional bits reserved for mapping into the ATM control bits in the cell format. The Frame Relay format and FUNI both pass through a frame switch. See Frame Relay and Frame UNI.

Further Notice of Proposed Rule Making

FNPRM. An Federal Communications Commission term. A Further Notice of Proposed Rule Making is issued by the Commission to further clarify and seek more information and public comment on the Commission's proposed changes. See Notice of Proposed Rulemaking.


Verb: To blend together through melting. Noun: An electrical device typically consisting of a wire or strip of fusible metal that melts to interrupt an electrical circuit when current exceeds the rated level of the fuse. The idea is that in any electrical circuit, the fuse should be the weakest point ” thus the point that heats up when things go wrong and melts. Better the fuse melts than your expensive PBX. See also Circuit Breaker.

Fuse Alarm Panel

FAP. A distribution panel at the top of the rack. Each device gets its power from the rack. To protect the rectifier from an over-current condition, each device has its own fuse.

Fused Coupler

A method of making a mulmode or single-mode coupler by wrapping optical fibers together, heating them, and pulling them to form a central unified mass so that light on any input fiber is coupled to all the output fibers.

Fused Fiber

A bundle of fibers fused together so they maintain a fixed alignment with respect to each other in a rigid rod. See also Fused Coupler.

Fused Quartz

The precise term for glass made by melting natural quartz crystals.

Fusible Links

Short lengths (about 25 feet) of fine-gauge wire pairs inside metallic sheath cable that melt to interrupt an electrical circuit and to prevent overheating in building wiring and equipment.


The process in which atomic nuclei collide so fast that they stick together and emit a large amount of energy. In the center of most stars, hydrogen fuses into helium. The energy emitted by fusion supports the star's enormous mass from collapsing in on itself, and causes the star to glow.

Fusion Splicing

In optical transmission systems using solid transmission media, the joining together of two media by butting them, forming an interface between them, and then removing the common surfaces so that there be no interface between them. Thus, no reflection or refraction at the former interface occurs.


Fiber Under Test.

Futility Computing

See Utility Computing.


  1. The future isn't what it used to be.

  2. Economists are incredibly accurate at forecasting the past.

  3. "Never prophesize about anything, especially the future." Samuel Goldwyn.


When a noun, A term used to describe a phone system (or any technology) that supposedly won't become technologically outdated (at least anytime soon). There's no such thing. When a verb, as in to futureproof, it means installing fiber to each outlet.

Future Public Land Mobile Telecommunication System


Future Shock

"Man has a limited biological capacity for change. When this capacity is overwhelmed, he is in future shock," defined by Alvin Toffler in his book of the same name published in 1970.

Fuzzy Logic

Fuzzy logic is the newest wrinkle in the ancient science of controlling processes that involve constantly changing variables . Contrary to its name, fuzzy logic is a very precise sub discipline in mathematics. It was invented in the 1960s by University of California at Berkeley's Russian-born Iranian computer science professor Lotfi Zadeh. It enables mathematicians and engineers to simulate human thinking by quantifying concepts such as hot, cold, very far, pretty close, quite true, most usually, almost impossible , etc. It does this by recognizing that measurements are much more useful when they are characterized in linguistic terms that when taken to the fourth decimal point. Fuzzy logic reduces a spectrum of numbers into a few categories called membership groups. Within five years virtually all consumer goods will come with fuzzy logic. Already fuzzy logic is inside video camcorders (to reduce the motion of the camera), in washing machines (to figure the optimum mix of washing conditions for that weight and filth).


Field Verification Office.


Flexible Vocabulary Recognition.


Fixed Wireless Access. Fixed wireless consists of a radio link to the home or the office from a cell site or base station. This "fixed" wireless link replaces the traditional wireless local loop. According to Northern Telecom, FWA is the solution of choice in sparsely - developed areas where potential subscribers have been on lengthy waiting lists, in dense urban areas where rapid expansion is desirable and in suburban settings where new neighborhood developments can be provisioned quickly with FWA.


Abbreviation for "For What It's Worth;" commonly used on E-mail and BBSs (Bulletin Board Systems).


See Fixed Wireless Local Loop.


Foreign Exchange. A Central Office trunk which has access to a distant central office. Dial Tone is returned from that distant Central Office, and a location can be reached in the area of the foreign Central Office by dialing a local number. This will provide easier access for customers in that area and calls may be made anywhere in the foreign exchange area for a flat rate. In short, a FX line is a special access circuit that provides service between a telephone at a customer location and a distant central office. A foreign exchange area is any area other than that serving the geographic area in which the telephone is located. See also Foreign Exchange and FXO.


Fiber Switch Cross-Connect. A type of Optical Cross-Connect (OXC). See OXC.


Foreign Exchange Office. Foreign exchange (FX) service is a service that can be ordered from the telephone company that provides local telephone service from a central office which is outside (foreign to) the subscriber's exchange area. In its simplest form, a user can pick up the phone in one city and receive a dial tone in the foreign city. This type of connection is provided by a type of trunk called foreign exchange (FX) trunks. FX trunk signaling can be provided over analog or T-1 links. Connecting POTS telephones to a computer telephony system via T-1 links requires a channel bank configured with FX type connections. To generate a call from the POTS set to the computer telephony system, you will need a FXO (foreign exchange office) connection configured. To generate a call from the computer telephony system to the POTS set, you will need a FXS connection configured. See FX.


Foreign Exchange Station. See FXO.


An Internet term. An abbreviation for the phrase "for your information." There is also a series of RFCs put only by the Network Information Center called FYIs. They address common questions of new users and many other useful things.


Fernmeldetechnisches Zentralamt. Telecom approval authority Austria, literally translated "long distance communications technical central office." All that in two words. Not bad.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133 © 2008-2017.
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