U is 1.75" inches. Us (i.e. the plural of U) are used as a measurement for servers in standard 19 inch racks. So a 1U server is 1.75" high and 19" wide. A 2U server is 3.5 inches high. Most servers are 1U.

U Band

The optical band, or window, specified by the ITU-T at a wavelength between 1625nm and 1675nm (nanometers) for fiber optic transmission systems. See also C- Band, E-Band, L-Band, O-Band, and S-Band.

U Interface

An ISDN term . The reference point for a BRI (Basic Rate Interface) connection between a telephone company local loop and a customer premises. BRI is intended for consumer, SOHO (Small Office Home Office), and small business applications. The U Interface specifies a single-pair loop (physical two-wire twisted pair) over which a logical four-wire circuit is derived. The resulting digital local loop supports three full duplex channels ” two B (Bearer) channels, and one D (Delta, or Data) channel. Each of the B channels provides 64 Kbps of bandwidth, and is designed to support actual user data payload. The D channel provides 16 Kbps of bandwidth, 9.6 Kbps of which can be used to support X.25 packet data traffic, and the balance of which is reserved for signaling and control purposes. There are two line coding techniques used in the U interface: 2B1Q is used in North America, and 4B3T in Europe. The U Interface is designed to work over a maximum distance of 18,000 feet, which addresses the vast majority of US local loops , with loss up to 42 dB (decibels). You screw the two "U" wires (local loop pair) coming in from your local ISDN CO into a black box about the size of desk printing calculator, called an NT-1. Out the side of the black box comes four wires, which are called the "S Bus." Onto these four wires you can attach, in a loop configuration (also called single bus), as many as eight ISDN terminals, telephones, fax machines, etc. See 2B1Q, 4B3T, and ISDN.

U Law

Actually it's Mu Law, but the "Mu" symbol isn't available on conventional keyboards. Mu Law is a voice amplitude compression/expansion quasi- logarithmic curve, based on the approximation with 15 linear segments. Used for PCM encoding/decoding in North America. See Mu Law and PCM.

U Plane

The user plane within the ISDN protocol architecture; these protocols are for the transfer of information between user applications, such as digitized voice, video and data; user plane information may be carried transparently by the network or may be processed or manipulated (e.g. A- to u-law conversion).


See U Band.

U Reference Point

In the U.S., the point that defines the line of demarcation between user-owned and supplier-owned Integrated Services Digital Network (ISDN) facilities.


An ADSL term for the functional interface between the "U" (standard, two-wire, twisted pair local loop) and the POTS splitter at the Centralized (i.e., Central Office) end of the network. The functional equivalent of the U-C at the premise end of the network is known as the "U-R." The asymmetric nature of this technology requires that the "C" and "R" interfaces be distinguished. See also ADSL, Splitter and U-R.


Unlicensed-National Information Infrastructure. A group of three frequency bands, each of 100 MHz in the 5 GHz band, set aside by the FCC in January 1997 for support of a projected family of high-speed, low-power, wireless voice and data devices. Band 1: 5.15 - 5.25 GHz/200 mW EIRP max/Indoor use only; Band 2: 5.25-5.35 GHz/1 W EIRP max/campus applications; and Band 3: 5.725 - 5.825 GHz/4W EIRP max/local access. The U-NII band is being used now for wireless last mile access (as is ISM band) in a point- to-point and point-to-multipoint fashion. Multiple vendors are working to commercialize equipment for this purpose.


An ADSL term for the functional interface between the "U" (standard, two-wire, twisted pair local loop) and the POTS splitter at the Remote (i.e., customer premise) end of the network. The functional equivalent of the U-R at the premise end of the network is known as the "U-C." The asymmetric nature of this technology requires that the "C" and "R" interfaces be distinguished. See also ADSL, Splitter and U-C.


  1. User Agent. An OSI application process that represents a human user or organization in the X.400 Message Handling System. A US creates, submits, and takes delivery of messages on the user's behalf . See also Browser Sniffing.

  2. User Agent. An end system, or endpoint, that acts on behalf of a user. In SIP (Session Initiation Protocol), there are two types of UA: User Agent Clients (UACs), and User Agent Servers (UASs). The UAC initiates a request which is sent to a UAS, which then returns responses. See also SIP.


User Agent Client. See UA.


Universal Asymmetric Digital Subscriber Line. A new standard from the telephone companies in order to provide faster access to the Internet for their subscribers and to compete against cable modems. See also Cable Modem and DOCSIS.


Universal Asynchronous Receiver/Transmitter. Also called a Shift Register. PCs have a serial port, which is used for bringing data into and out of the computer. The serial port is used for data movement on a channel which requires that one bit be sent (or received) after another, i.e. serially . The UART is a device, usually an integrated circuit chip that performs the parallel-to-serial conversion of digital data to be transmitted and the serial-to-parallel conversion of digital data that has been transmitted. The UART converts the incoming serial data from a modem (or whatever else is connected to the serial port) into the parallel form which your computer handles. UART also does the opposite . It converts the computer's parallel data into serial data suitable for asynchronous transmission on phone lines. UART chips control the serial port/s on personal computers. Now read the next definition. See also 16550, Interrupt, Interrupt Latency, Interrupt Overhead, Interrupt Request and UART Overrun .


User Agent Server. See UA.


A measure of performance. The duration is seconds for which the resource was unavailable.

UART Overrun

UART overruns are errors received from a universal asynchronous receiver/transmitter when receiving equipment cannot match transmission speed. UART overrun occurs when the UART's receive buffer is not serviced quickly enough by the CPU, and the next incoming byte of data crashes into the previous byte. The previous byte is then lost, forcing the communications driver to report and error. Your communications software must then ask for a retransmission of the lost data. High interrupt overhead is the most common cause of a UART overrun. The easiest way of solving UART overrun is to get yourself a UART with a 16 byte buffer (like the 16550), not one of the old more typical one byte buffer UART. See 16550 and UART.


UnAvailable Seconds. A count of the number of seconds that a circuit or path is unavailable.


User Acceptance Testing.


The Universal ADSL Working Group (UAWG), was composed of about 250 leading companies in the PC, networking, and telecommunications industries, all of which worked to develop a set of contributions building on the ANSI T1.413 standard intended to create quick deployment and adoption of G.Lite ADSL. The group aimed to accelerate both full-rate and G.Lite ADSL deployments. The group foresaw G.Lite ADSL modems being a preferred PC modem technology by the year 2000. The effort was successful. On June 8, 1999 the UAWG disbanded, handing over its remaining work to the ADSL Forum. See ADSL and ADSL Forum.


Unsolicited Bulk E-mail. See Spam Mail.


According to Alcatel, ubiquity is the name of a feature that allows a mobile worker's cellular phone to be integrated seamlessly with the corporate voice network. Ubiquity allows employees to have a single number and voice mailbox, increasing accessibility and eliminating the frustrating experience of callers having to try multiple numbers (desk phone, cell phone, etc.) to reach an employee. One-number ubiquity services increase convenience and save time in the following ways:

When users are off-site, they have access to the same features as if they were at the corporate location. Ubiquity allows mobile users' cell phones to be used as an extension to the corporate network, so they can receive calls and access all features from anywhere . For instance, a traveling employee can take advantage of the company's dial-by-name directory from his cell phone keypad. Ubiquity gives callers choices about how to reach an employee who is away from his desk. For example, an auto attendant allows callers to leave a voice message, have their call automatically forwarded to the employee's cell phone, or speak with a live attendant. The caller does not have to hang up and try another number, and the employee does not have to give out his direct cellular phone numberhe decides when and how he can be reached. Ubiquity services are fully configurable based on user needs. For example, if a user does not want to be disturbed by incoming calls to her cell phone, she can forward calls to her voicemail or an attendant. If a user is out of range or not available, an auto attendant allows callers to chose whether they'd like to leave a message or talk to an operator. Another convenience provided by ubiquity services is a single voice mailbox on the corporate network. In other words, if a call is routed to an employee's cell phone but is unanswered, the call is "pulled back" to the corporate network so the caller can record a voicemail message. Employees have access to all their messages in one place.


Undefined Bit Rate or Unspecified Bit Rate. Traffic class defined by the ATM Forum. UBR is an ATM service category which does not specify traffic related service guarantees . Specifically , UBR does not include the notion of a per-connection negotiated bandwidth. No numerical commitments are made with respect to the cell loss ratio experienced by a UBR connection, or as to the cell transfer delay experienced by cells on the connection.


  1. Universal Controller.

  2. Unit Controller.

  3. Unified Communications. See also Unified Messaging.


Utility Communications Architecture. An architecture for networks used to monitor and control electric power distribution systems.


University Corporation for Advanced Internet Development. Here's the explanation: Internet2 is the next generation Internet, replacing the current Internet exclusively for the use of member universities, Internet2 is a UCAID project. As a result of what they saw as the deteriorating performance of the Internet, 34 U.S. universities announced in October, 1996 the formation of Internet 2. Subsequently, the central goals of the project were adopted as part of the Clinton administration's Next Generation Initiative (NGI). This second version of the Internet is a collaboration of the National Science Foundation (NSF), the U.S. Department of Energy, over 110 research universities, and a small number of private businesses. Each participating university has committed at least $500,000 to fund the project. Intended to serve as a private Internet for the exclusive use of its member organizations, it will be separate from the traditional Internet. The network eventually will operate over fiber optic transmission facilities at speeds of up to 2.4 Gbps (SONET OC-48), although current speeds of connection are at 155 Mbps (OC-3) and 622 Mbps (OC-12), but going higher to OC-48. Internet2 will connect through gigiPOPs, switches with throughput in the range of billions of packets per second, and will run the IPv6 protocol. www.internet2.edu. See also Internet.


Uniform Commercial Code.


  1. Uniform Call Distributor. A device for allocating incoming calls to a bunch of people. Less full-featured than an Automatic Call Distributor. For a bigger explanation see Uniform Call Distributor.

  2. Urine Collection Device. Initials used in the original Mercury Space Program. NASA didn't have one ready for Alan Shepard's first suborbital flight - with predictable results.


  1. Uplink Control System. Software used to support the secure delivery of digitally compressed services.

  2. Universal Character Set. A standard coding scheme developed in 1993, jointly by the ISO and IEC, and specified in ISO 10646. UCS-2, also known as BMP (Basic Multilingual Plane) is a 16-bit scheme which merged with Unicode to form one standard character set. UCS-4 is a 32-bit variant, which is conceptual only. See also BMP and Unicode.


Universal Coordinated Time. See ZULU Time.

UDC Connector

These connectors are used to terminate 2-pair STP cable. UDC connectors form a hermaphroditic connection, meaning that there is no jack ( female end) or plug (male end).


Universal Description, Discovery and Integration. UDDI is one of the key technical underpinnings of e-commerce. UDDI, which was developed by Ariba, IBM, Intel, Microsoft and SAP, is a set of specifications established for building online registries of companies and the goods and services they provide. UDDI is a kind of electronic directory for businesses that want to locate customers and suppliers through the Internet. The registries should include not just product data and contact information, but the technical details necessary to connect to a given supplier's own e-commerce systems. See Business to Business and Enterprise Application Integration.


Universal Disk Format. See OSTA.


Unrestricted Digital Information.


A dumb GTE abbreviation, for Universal Dialing Keyset, a key pad that is switchable for either TONE or PULSE dialing. Outside GTE's private world, a keyset would mean a KEY TELEPHONE, not part of a phone.


  1. Universal Digital Loop Carrier

  2. Univac Data Link Control. Sperry-Univac (now UNISYS) version of a bit-oriented computer protocol based on the CCITT's HDLC.


The ultimate dumb, open programmable (UDOP) switch built from multi-vendor SC-based products. A term coined by Dialogic.


User Datagram Protocol. User Data Protocol is part of the TCP/IP protocol suite. It was created to provide a way for applications to access the connectionless features of IP. UDP provides for exchange of datagrams without acknowledgements or guaranteed delivery. This protocol is normally bundled with IP-layer software. UDP is a transport layer (layer 4 of the OSI reference model), connectionless mode protocol, providing a ( potentially unreliable, unsequenced, and/or duplicated ) datagram mode of communication for delivery of packets to a remote or local user. See also CLTP.


User Datagram Protocol/Internet Protocol. See UDP.


Universal Data Patch Unit.


Unidirectional HDSL (High-bit-rate Digital Subscriber Line). A variation on the HDSL theme proposed by a small group of companies in Europe. See HDSL and xDSL.


Ultra -Dense Wavelength Division Multiplexing. Identified as the next generation of DWDM, UDWDM is planned to support as many as 400 wavelengths per optical fiber. See DWDM and WDM for detailed discussions of the technology.


Universal Equipment Module. A Nortel Networks' acronym. The basic unit of Meridian 1 PBX modular packaging. A UEM is a self-contained hardware cabinet housing a card cage, with a power supply, backplane, and circuit cards. If the UEM has the card cage for an AEM installed, it functions as an AEM.


A program which enables a FIDO compatible bulletin board system to exchange UUCP mail with UUCP sites.


Upstream Failed Signal State.




Ultra High Frequency. Portion of the electromagnetic spectrum ranging from about 300 MHz to about 3 GHz. The frequency ban includes television and cellular radio frequencies.


  1. User Interface, as in GUI, or Graphical User Interface.

  2. UNIX International is a consortium of computer hardware and software vendors which is interested in the development of open software standards for the UNIX industry. Prominent members include AT&T, Sun, UNISYS and Fujitsu.


Universal International Freephone Number. In early June 1996, the ITU-T released the E.169 standard, along with the revision of E.152. This standard allows International Freephone Service (IFS) customers to be allocated a unique Universal International Freephone Number (UIFN) which will remain the same throughout the world, regardless of country or telecommunications carrier. "Freephone," the generic name for what we call "InWATS" in North America, is a service which permits the cost of a telephone call to be charged to the called party, rather than the calling party. In North America, "Freephone" numbers are in the area codes 800, 888, and 877 (in order of introduction). According to the ITU-T, a UIFN is composed of an international prefix (e.g., 011 in the U.S.), a three- digit country code (800) for global service application, and an 8-digit Global Subscriber Number (GSN). The resulting eleven-digit fixed format is "+ 800 XXXX XXXX," with "+" representing the international access code, and "X" being any number 0-9. If available, companies can choose the digits they wish and embed existing Freephone numbers into the available number space. For example, the North American InWATS number 1-800- HNEWTON might translate into the UIFN "+ 800 HNEWTON1." (These are not my real numbers, so please don't dial them. You'll cost someone else some time and money.) See also 800 Service, IFS, and ITFS.


Universal Information Services. AT&T's vision of a single fully-integrated, user-defined digital network with a universal port of entry. Very similar to ISDN, now aggressively adopted by AT&T.


UK Education and Research Networking Association. See JANET, Super-JANET.


Underwriters Laboratories, a privately-owned company that charges manufacturers a stiff fee to make sure their products meet various safety standards, some of which UL itself develops. A UL label on a product has a very specific message. It says the product conforms to the safety standards ” nothing more. It does not affirm that the product will work. Among other things, UL tests inside wire and cable products to ensure that they conform to the National Electric Code (NEC). Specifically, such tests are conducted to determine compliance with UL 444, which addresses flame test procedures. Other organizations, such as the ETL Testing Laboratories, also test for NEC compliance, and also use UL 444. www.ul.com. See also National Electric Code, UL Approved and UL Cable Certification Program.

UL 1449

A method of rating and approving surge suppressors. This Underwriters Laboratories measurement is important as it tells if you're buying a true surge suppressor or just an extension cord. This listing measures how much voltage actually reaches the attached equipment after going through the surge suppressor . It's on a scale from about 330 volts to 6,000 volts. The lower the rating, the greater the protection. Decent surge suppressors tend to be rated around 400 volts for the basic units and 340 for the advanced and superior models. In short, check for UL 1449 rating on your surge arrestor before you buy it.

UL 1459

Effective 7/1/91, telephone equipment manufacturers will be required to provide protection from current overloads and power line crosses on equipment systems. Equipment systems covered under this listing requirement include single- and multi-line telephones, PBXs, key systems and central office switches. In general, the UL 1459 requirements apply to any location where wires enter a building from the public network, as well as in most IROB (In Range Out of Building) situations. See also NEC Requirements and Underwriters Laboratories.

UL 1863

This requirement covers miscellaneous accessories intended to be electrically connected to the telecommunications network. The listing requirement applies to components that comprise the premises communications wiring system from the point of demarcation up to and including the final outlet providing modular plug and jack connection (or equivalent). Requirements are listed under Communication Circuit Accessories, UL 1863. Listing equipment for all other equipment will be covered under UL 1459, effective July 1, 1991. See also NEC Requirements and Underwriters Laboratories..

UL 444

The Underwriters Laboratories flame test procedure that is used to test inside wire and cable systems to ensure that they are in compliance with the National Electric Code (NEC). The NEC contains provisions that require that voice and data cable systems are low-smoke and fire-retardant. See also National Electric Code.

UL 497 & 497A

According to the National Electrical Code, primary and secondary protection systems that will be used on a telephone circuit must be listed for that purpose. The listing requirements are UL 497 for primary protection systems and UL 497A for secondary protection systems. See also NEC Requirements and Underwriters Laboratories.

UL Approved

Tested and approved by the Underwriters Laboratories. The Underwriters Laboratories, Inc. was established by the National Board of Fire Underwriters to test equipment affecting insurance risks of fire and safety. Most phone systems are tested and approved. Most of the testing focuses on the power supply feeding the phone system. The power supply is that little black box that plugs into the AC wall outlet at one end, takes 120 volt AC and converts it to low voltage DC power that the phone system typically runs on. If the power supply tests OK, then that's usually sufficient UL testing. For it is the power supply ” and what happens to the commercial AC power that feeds into the power supply ” that determines the potential fire hazard of your phone system. After many fire deaths in recent years , most local communities are a lot more concerned about UL Approval of installed telephone equipment. Fire departments have been known to zealously enforce these rules. In addition to the UL approval, the other major fire concern is the use of proper wire in new building construction, with especial emphasis on teflon-covered cable in plenum ceilings. See also UL, an entry which talks about UL's expanding certification business. See also UL Cable Certification Program.

UL Cable Certification Program

Underwriters Laboratories, in conjunction with companies such as Anixter, has developed a Data-Transmission Performance-Level Marking Program that covers UL Listed communications cable or power-limited circuit cable. The UL program identifies five levels of performance. UL evaluates cable samples to all of the tests required for each level. Only Levels II through V require testing.

LEVEL I: Level I cable performance is intended for basic communications and power-limited circuit cable. There are no performance criteria for cable at this level.

LEVEL II: Level II cable performance requirements are similar to those for Type 3 cable (multi-pair communications cable) of the IBM Cabling System Technical Interface Specification (GA27-3773-1). These requirements apply to both shielded and unshielded cable constructions. Level II covers cable with two to 25 pair twisted pairs of conductors.

LEVEL III: Level III data cable complies with the transmission requirements in the Electrical Industries Association/Telecommunications Wiring Standard for Horizontal Unshielded Twisted-Pair (UTP) Cable and with the requirements for Category 3 in the proposed EIA/TIA Technical Systems Bulletin PN-2841. These requirements apply to both shielded and unshielded cables.

LEVEL IV: Level IV cable complies with the requirements in the proposed National Manufacturer Association (NEMA) Standard for Low-Loss Premises Telecommunications Cable. Level IV requirements are similar to Category 4 requirements of the proposed Electronic Industries Association / Telecommunication Industry Association (EIA/TIA) Technical Systems Bulletin PN-2841. These requirements apply to both shielded and unshielded cable constructions.

LEVEL V: Level V cable complies with the requirements in the proposed National Electrical Manufacturers Association (NEMA) Standard for Low-Loss Extended-Frequency Premises Telecommunications Cable. Level V requirements are similar to Category 5 requirements of the proposed Electronic Industries Association/Telecommunication Industry Association (EIA/TIA) Technical Systems Bulletin PN-2841. These requirements apply to both shielded and unshielded cable constructions.

UL evaluates communications and data transmission cable to one of two UL Safety Standards: UL 444, the Standard for Safety for Communications Cable; and UL 13, the Standard for Safety for Power-Limited Circuit Cable.


Unified Local Area Network Architecture. An ongoing U.S. Air Force project aimed at creating a series of interconnected local area networks using Transmission Control Protocol/Internet Protocol (TCP/IP) as the unifying transport layer.


Ultra-Long-Haul. While the term is imprecise, ULH refers to a fiber optic circuit that extends a very long distance through the use of various repeater and/or amplifier technologies.


Upper Layer Protocol. In the context of the OSI Reference Model, a ULP is an application-level protocol which may reside at a higher layer than something like ATM (Layers 1 and 2) or TCP (Layer 3).


User Location Service (ULS) provides a mechanism for users of Microsoft's NetMeeting to locate other people on the Internet, even if their Internet addresses change. A sample of the ULS can be found at http://uls.microsoft.com/.


Ultra Large Scale Integration, the technique of putting millions of transistors on a single integrated circuit. Compare with LSI (Large Scale Integration) and VLSI (Very Large Scale Integration).


IBM's product in multimedia ” combining sound, motion video, photographic imagery, graphics, text and touch into a unified, natural interface representing, in IBM's words, the ultimate in multimedia solutions. Ultimedia supports both Ultimotion and Indeo video. Ultimedia was coined in the Spring of 1992.


IBM's video compression algorithm. Although IBM supports Indeo video technology in OS/2 and Windows systems, IBM feels several OS/2 vertical applications are adequately served by the Ultimotion algorithm. Ultimotion does not offer software scalable playback or single step compression. See Ultimedia.


UCS Transformation Format 8. UCS (Universal Character Set) is a standard coding scheme developed in 1993, jointly by the ISO and IEC. UCS-2, also known as BMP (Basic Multilingual Plane) is a 16-bit scheme which merged with Unicode to form one standard character set. UTF-8 is a transformation format which is multibyte Unicode, and ASCII- compatible. UTF-8 resolves issues of Unicode coding, which may contain odd character strings that are unreadable by certain UNIX tools. UTF-8 is defined in the IETF's RFC 2279. See also ASCII, UCS, and Unicode.


UMTS Terrestrial Radio Access. See also UMTS.

Ultra-dense Wavelength Division Multiplexing


Ultra Hi-Res

Ultra high resolution. Properly speaking, the term should be for monitors with resolutions of 1,200 x 800, 1,024 x 1024 or better, but it is sometimes used to describe monitors with 800 x 600 resolution and above.

Ultra High Frequency

Frequencies from 300 MHz to 3000 MHz.

Ultra High Vacuum/Chemical Vapor Deposition

UHV/CVD. The process, developed by an IBM research team led by Bernard Meyerson, by which germanium is added to silicon to form silicon germanium (SiGe).

Ultra Wideband

UWB. On February 14, 2002 the Federal Communications Commission (FCC) approved the limited use of UWB for commercial use. This wireless technology has the potential to underpin new, more efficient wireless networks that would offer a less expensive alternative to so-called third-generation wireless service offerings from incumbent carriers . Ultra wideband is new radar-like technology that actually has its roots in work on time-domain electromagnetics begun in 1962. Previously known variously as "baseband," "carrier-free," or "impulse," UWB transmission systems are typically centered within the 200 MHz to 4 GHz band and emit an average radiated power of approximately 125uW. According to my techie friends , an ultra-wideband system is a radiator with intentional emissions that have a fractional bandwidth greater than or equal to 25%, with the fractional bandwidth being the 20 dB bandwidth divided by the center frequency. UWB systems are characterized by their low probability of intercept and detection (LPI/D), multipath immunity, high data throughput, and precision ranging and localization. UWB is used for penetrating thick bodies, such as the ground or the walls of a building. UWB technology allows a radar system to detect buried objects such as plastic gas pipes or reveal hidden flaws in roads , bridges, or airport runways. UWB will provide law enforcement officers with a means of covert communication and to provide radar systems that will enable fire and rescue personnel to find persons inside damaged, burning, or smoke filled buildings . UWB also is used in specialized ground-penetrating radar systems to find human bodies buried in shallow graves under parking lots. UWB radios have been developed that achieve non line-of- sight communications through the use of surface or ground wave propagation. Operating at frequencies well below 100 MHz, these radios support voice and data at rates up to 128 Kbps with an operational range of 1-5 miles with intervening foliage, buildings and hills. Also based on UWB technology, electronic license plates have been developed with built-in collision avoidance radar. Much of the early work on UWB was performed under classified U.S. government restrictions, and much of that body of knowledge remains classified .

Ultrasonic Bonding

The use of ultrasonic energy and pressure to join two materials.


That portion of the electromagnetic spectrum in which the wavelength is just below the visible spectrum, extending from approximately 4 nanometers to approximately 400 nanometers. Some scientists place the lower limit at values between 1 and 40 nanometers, 1 nm being the upper wavelength limit of X-rays. The 400-nm limit is the lowest visible frequency, namely violet . "Light" in the ultraviolet spectrum is used for erasing EPROMS.

Ultraviolet Fiber

Special fiber which extends the usable range into the UV region of the spectrum.

Ultrawide Band Radio

Also known as Digital Pulse Wireless. The new technology of ultrawide band radio uses a digital transmission consisting of small on-off bursts of energy at extremely low power but over the entire radio spectrum. According to the New York Times, "by precisely timing the pulses within accuracies of up to a trillionth of a second, the designers of ultrawide band radio systems are able to create low-power communications systems that are almost impossible to jam, tend to penetrate physical obstacles easily and are almost invulnerable to eavesdropping. Police officers could use such a system "to see through" walls and doors to detect the location of people. According to the New York Times, the most promising application for ultrawide band radio might eventually be an alternative to today's wireless office network technologies that are limited in speed. "Because of its design, ultrawide band advocates," according to the Times, say the technology has the potential to deliver vastly higher amounts of data because a large number of transmitters could broadcast simultaneously in close proximity without interfering with one another. See also Bluetooth.


  1. Micron ” one millionth of a meter.

  2. Unified Messaging. See Unified Messaging.

  3. Unit Manager.


An acronym for Upper Memory Area. See Upper Memory Area.


An acronym for Upper Memory Block, an area of upper memory (the area between 640KB and 1MB of RAM) in an MS-DOS PC that has been remapped with usable RAM. This allows device drivers and TSRs to be loaded high, into the UMB and out of conventional memory. See Upper Memory Area.


Plastic surgery performed on the navel, usually for cosmetic reasons.


UNI Management Entity: The software residing in the ATM devices at each end of the UNI circuit that implements the management interface to the ATM network.


Universal Messaging Interoperability Group. This group is an offshoot of AMIS (Audio Messaging Interchange Specification). The UMIG is being technically facilitated (their words) by the Information Industry Association in Washington, DC. The UMIG has two top priorities: First, to foster the development of "universal messaging," which entails integrating platforms supporting different types of messaging, such as voice processing, electronic mail and facsimile messaging to allow users to move easily among the three media. The second priority entails working towards standardized addressing and directory schemes that make it easy and intuitive for users to message one another.


Universal Mobile Telecommunications System. The technology envisioned for the next generation of GSM (Global System for Mobile Communications). More specifically, UMTS is the European member of the IMT-2000 (International Mobile Telecommunications for the year 2000) family of 3G (3rd Generation) wireless standards, and is based on GSM (Global System for Mobile communication). UMTS is intended to support data transfer rates of 144 Kbps for vehicular traffic, 384 Kbps for pedestrian traffic, and up to 2 Mbps in support of in-building services. The plan is that UMTS, once fully implemented, will allow mobile voice and data users to maintain constant connectivity to the Internet, regardless of where they travel. ETSI (European Telecommunications Standards Institute) currently is evaluating proposals for the UMTS standard. UMTS services are expected to be available in 2002, which pretty much blows the "2000" part of IMT-2000. On March 9, 1999, Stephane Tronchon, "legal adviser" to ETSI, wrote me a snotty letter informing me that UMTS is a trademark and is owned by ETSI and that I shouldn't mention it "without our authorization and without any acknowledgement concerning ownership." Now I have. Pity that Ms. Tronchon has nothing better to do than send poor lexicographers silly letters . It seems like she could better spend her time working to get UMTS finalized by the year 2000, like it was supposed to be. (Actually, the "2000" part means 2,000 Kbps, or 2 Mbps, which is the highest level of bandwidth contemplated. I just couldn't resist the opportunity to take a cheap shot at Ms. Tronchon, even if it was technically flawed.) See also 3G, GSM, IMT-2000, Lexicographer, and Snotty.

UMTS Terrestrial Radio Access

UTRA. UMTS terrestrial (versus non-terrestrial, or satellite) radio access standards address radio parameters including radio frequency, channel spacing, modulation techniques, and protocols which form the communications link between the mobile station and the base station. The access techniques include FDD (Frequency Division Duplex) and TDD (Time Division Duplex). See also FDD, TDD, and UMTS.


Industry jargon for UNreachable, an unsuccessful call where the agent is unable to speak to the contact or decision maker.


The worldwide organization responsible for defining, coordinating and integrating EDI (Electronic Data Interchange) standards under the auspices of the United Nations.

Unassigned Cell

An ATM filler cell used to occupy available bandwidth when there are no assigned (user-generated) cells to send. Unassigned cells carry a PCI/VCI (Protocol Control Information/Virtual Channel Identifier) value of 0/0. Unassigned cells are discarded at the ATM Layer. They can be replaced by assigned cells, as required, during the process of cell multiplexing. See also ATM Layer, ATM Protocol Reference Model, PCI, VCI, and Idle Cell.


Equipment working without a human attendant or operator. There are pros and cons to operators. On the pro side, they offer a personalized service that's absolutely critical to customer goodwill. On the con side, they can be slow and cumbersome. They can be very irksome when you know you could do that task yourself, but have to wait for the operator. Some companies have only one main number. Some companies use a main number and DID ” on their Centrex and their PBX. Some companies use an automated attendant and an operator. There's more flexibility with DID and a main number, or Centrex DID and a main number. Customers without knowledge dial the main number. Customers with knowledge can dial direct DID numbers. See also Automated Attendants.

Unattended Call

Calls placed by a computerized dialing system in anticipation of an agent being available to answer the call. A called party is detected answering the phone and no agent is available to serve the call. The system hangs up on the party so as not to create any greater nuisance than has already occurred. The telemarketing industry does not believe that an unattended call can be queued for the next available agent.

Unattended Operation

Transmission automatically controlled; not required a human operator to function.


Unbalanced refers to the lack of electrical balance between conductors that comprise a circuit. Twisted pair circuits are balanced, which is to say that the signals across both conductors are electrically similar, although they intentionally are out of phase in order to minimize crosstalk. Coaxial cables, on the other hand, are intentionally unbalanced, as the inner conductor carries positive and negative voltages while the outer conductor is maintained at zero voltage. See also Unbalanced Line.

Unbalanced Line

An unbalanced line is an electrical circuit comprising two conductors that do not carry equivalent electrical charges with respect to ground. Some lines are intentionally unbalanced, while others must be balanced to work correctly. Coaxial cables, for example, are intentionally unbalanced. The center coax conductor carries the information to be transferred, and carries an electrical charge; the outer conductor, or shield, is maintained at zero voltage. Twisted pair circuits, on the other hand, must be balanced. In a balanced line, both conductors carry equivalent electrical charges, which are exactly opposite in polarity. That minimizes the potential for crosstalk.

A telephone circuit in which the voltages on the two conductors are not equal with respect to ground. Unbalanced lines give poor phone service. Lines can become unbalanced when they come from the central office or when they are in the PBX or the on site phone system. Problems can and should be repaired for decent quality results. Coaxial cables are unbalanced, as the center conductor carries an electrical charge, but the outer conductor, or shield, is maintained at zero voltage.


  1. Services, programs, software and training sold separately from the hardware.

  2. Services and products leased by local phone companies as a result of the Telecommunications Act of 1996. For a much better explanation, see Unbundled Network Element.

Unbundled Access Ability

Refers to the ability of a CLEC to access and use components of the ILEC's network (called network elements) to fill in the CLEC's networks.

Unbundled Network Element

UNE (pronounced you nee). The Telecommunications Act of 1996 requires that the ILECs (Incumbent Local Exchange Carriers) unbundle their NEs (Network Elements) and make them available to the CLECs (Competitive LECs) on the basis of incremental cost. UNEs are defined as physical and functional elements of the network, e.g., NIDs (Network Interface Devices), local loops and subloops (portions of local loops), circuit-switching and switch ports, interoffice transmission facilities, signaling and call-related databases, OSSs (Operations Support Systems), operator services and directory assistance, and packet or data switching. When combined into a complete set in order to provide an end-to-end circuit, the UNEs constitute a UNE-P (UNE-Platform). Unbundled Network Elements is a term used in negotiations between a CLEC (Competitive local Exchange Carrier) and the ILEC (Incumbent Local Exchange Carrier) to describe the various network components that will be used or leased by the CLEC from the ILEC. These components include such things as the actual copper wire to the customers, fiber strands, and local switching. The CLEC will lease these UNEs with pricing based on the previously-signed Interconnection Agreement between the CLEC and the ILEC. Typically, a CLEC will colocate a switch at the ILEC's wire center, then pay for the "unbundled" local loop to make a connection to the customer. Alternately, a CLEC might lease both an unbundled local loop and an unbundled switch, and make a connection to their network at the LEC's switch. See CLEC, ILEC, the Telecommunications Act of 1996, UNE Rate and UNE-P.

Unbundled Services

A CFRS service option in which the customer provides and services some of their own equipment at each site. Less expensive than Bundled service.


Here's an FCC defintion: Unbundling is the term used to describe the access provided by local exchange carriers so that other service providers may buy or lease portions of its network elements, such as interconnection loops to serve subscribers.


Universal naming convention. See also UNC NAMES .

UNC Names

Filenames or other resources names that begin with the string \\, indicating that they exist on a remote computer.

Uncontrolled Terminal

A user terminal that is on line at all times and that does not contain the logic that would allow it to be polled, called, or otherwise controlled by the device to which it is connected.

Under mouse arrest

Getting busted for violating an online service's rules of conduct. "Sorry I couldn't get back to you. AOL put me under mouse arrest."


A condition for launching light into a fiber in which not all the modes that the fiber can support are excited (i.e. turned on).

Underfloor Duct Method

A floor distribution method using a series of metal distribution channels, often embedded in concrete, for placing cables. This method uses one or two levels depending on the complexity of the system. Sometimes referred to as under- floor raceways. See also Raceways Method.


  1. In computing, a condition occurring when a machine calculation produces a non-zero result that is smaller than the smallest non-zero quantity that the machine's storage unit is capable of storing or representing.

  2. In the transmission sense, when the input signal is operating slightly slower than the synchronized output and extra data must be periodically inserted. Generally , the last frame is repeated.


Cable installed in buried conduit. Does not typically include cables buried directly in the ground.

Underground Plant

A term used to describe the network of splicing chambers, connecting sections of conduit and the cables which run though them.


In facsimile, a defect that occurs when the width of the scanning line is less than the scanning pitch.

Underload Syndrome

When you're bored, have few challenges or stmulus at work, you'll likely to get sick and/or depressed. This is now called underload syndrome.

Underlying Carrier

A common carrier providing facilities to another common carrier which then provides services to end users.


A network error indicating that buffer checks show the buffer as empty. Underruns shouldn't happen in a well managed network. An underrun is often a synchronization problem.

Understaffing Limit

A call center term. The percentage by which you'll allow the scheduling process to fall short of the required staffing level in any period. This typically provides more economical coverage during the least-busy periods of the day.

Underwriters Laboratories, Inc.

A non-profit laboratory which examines and tests devices, materials and systems for safety, not for satisfactory operation. See UL for a longer explanation.

Undesired Signal

Any signal that tends to produce degradation in the operation of equipment or systems.

Undetected Error Ratio

The ratio of the number of bits, unit elements, characters, or blocks incorrectly received and undetected, to the total number of bits, unit elements, characters , or blocks sent.

Undirected Pickup

A phone system feature. Undirected Pickup lets you pickup any call ringing at any extension in the pickup group in which your extension is a member. The pickup groups are pre-programmed in the switch.

Undisturbed Day

A day in which the sunspot activity or ionospheric disturbance does not interfere with radio communications.


(pronounced you nee). Unbundled Network Element. The Telecommunications Act of 1996 requires that the ILECs (Incumbent Local Exchange Carriers) unbundle their NEs (Network Elements), which must be made available to the CLECs (Competitive LECs) on the basis of incremental cost. This means that CLECs will pay the additional costs the ILECs incur in making these facilities available. the words "incremental cost" are meant to signal to the ILECs that they are not to inflate the price of these facilities by adding overhead costs (e.g. the salary of the ILEC's people in charge of investor relations). UNEs are defined as physical and functional elements of the network, e.g., NIDs (Network Interface Devices), local loops, switch ports, and dedicated and common transport facilities. When combined into a complete set in order to provide an end-to-end circuit, the UNEs constitute a UNE-P (UNE-Platform). Unbundled Network Elements is a term used in negotiations between a CLEC (Competitive local Exchange Carrier) and the ILEC (Incumbent Local Exchange Carrier) to describe the various network components that will be used or leased by the CLEC from the ILEC. These components include such things as the actual copper wire to the customers, fiber strands, and local switching. The CLEC will lease these UNEs with pricing based on the previously-signed Interconnection Agreement between the CLEC and the ILEC. Typically, a CLEC will colocate a switch at the ILEC's wirecenter, then pay for the "unbundled" local loop to make a connection to the customer. Alternately, a CLEC might lease both an unbundled local loop and an unbundled switch, and make a connection to their network at the LEC's switch. See CLEC, ILEC, the Telecommunications Act of 1996, UNE Rate and UNE-P.

UNE Rate

The fee, set by state regulators, that an ILEC charges a CLEC to unbundle network elements as part of making the local exchange market competitive. Rebundling is the process of putting UNEs back together by a CLEC to become part of a competitive service offering by him to a customer.


A common strategy used by facilities-based CLECs. A CLEC owns the local switch and leases the local loop from the ILEC. This is more capital intensive than UNE-P.


Unbundled Network Element-Platform. See UNE.

Unequal Access

Refers to long distance phone companies who do not take advantage of Judge Harold Greene's Equal Access divestiture provisions. Rather than a carrier selection code, unequal access carriers require you to dial a local seven digit number and punch in an authorization code. If the carrier elected to pay for Equal Access, you would just dial directly the same 10 digits you do today, and your local telephone company would give your billing number to your long distance company.


A command for getting back files you've accidentally erased. See MS-DOS.

Unfinished Business

See Last Piece of Unfinished Business.


Not connected to ground. PBXs, key systems and other phone systems will not work well when not connected to a solid ground because they have no place to send high voltage spikes (static electricity, lightning strikes, etc.) Improper grounding is probably the most common cause of phone system faults. Our feeling: the better the ground, the better the phone system performance. One way of grounding is the third wire of an electrical outlet. This may be OK if you check where that wire is ultimately connected to. You can ground to the metal cold water pipe. But that may connect to a plastic PVC pipe one floor below. Best to check. A ground ultimately ending firmly routed a dozen feet below the ground is best.


University of New Hampshire Interoperability Lab. A testing organization affiliated with the Research Computing Center of the University of New Hampshire which tests FDDI products for vendor interoperability.


Unhave is a verb which 19th century telegraphers used to say/send to mean that they didn't have something. This definition contributed by Jim Seymour.


User Network Interface. Specifications for the procedures and protocols between user equipment and either an ATM or Frame Relay network. The UNI is the physical, electrical and functional demarcation point between the user and the public network service provider. By way of example, the Frame Relay UNI involves both the user's FRAD (Frame Relay Access Device) and the carrier's FRND (Frame Relay Network Device) across a dedicated link. The ATM (Asynchronous Transfer Mode) UNI was developed and is promoted by the ATM Forum; the Frame Relay UNI, by the Frame Relay Forum.


User Network Interface A. A B-ISDN term for a SONET OC-3 link from the network to the premise, operating at 155 Mbps.


User Network Interface B. A B-ISDN term for a SONET OC-12 link from the network to the premise, operating at 622 Mbps.

UNI Interface

See UNI.


According top Faith Popcorn writing in "Dictionary of the Future," telecommunications companies will create "universal billing minutes" that are bought in advance, and can be used for landline or wireless calls.


A UNIX version of COBOL.


The communication from one device to another device over a network. In other words, a point-to-point communication. When you're Web browsing on the Internet or sending and receiving email, you are unicasting. Unicast communications (also called point-to- point communications) are sent between one network endpoint to another. An example of unicast communication is an email message. When a user sends an email to one recipient, his or her email client addresses and sends one message. If a user sends the same email to 10 recipients at once, her email client sends a separate copy of the message to each recipient. Unicasting is efficient for certain types of communications such as email and Web browsing; however, when multiple destinations require the same data, unicasting can be resource and bandwidth intensive. Imagine the following scenario: five end stations request a particular video stream. To unicast this data, the source creates five separate video streams. The transmission uses five times the amount of bandwidth required by one stream to traverse the network backbone. Five viewers may not use too much bandwidth, but consider the bandwidth used to unicast video to 500 or even 5,000 recipients. Unicasting (one to one communication) is often defined in comparison to its alternatives, multicasting (one to many), broadcasting (one to all). See Multicast and Broadcast.


  1. Communicating from one device to another. In contrast, multicasting sends one stream of information to many. See Unicast.

  2. As an ATM term, it is the transmit operation of a single PDU by a source interface where the PDU reaches a single destination.


Unicode is a 16 bit system for encoding letters and characters of all the world's languages. At 16 bits it can encode 65,536 characters. That's two raised to the 16th power. Work it out: Multiply 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2. Sixteen-bit characters (like Unicode) are also called Wide Characters. The first 128 codes of Unicode are identical to ASCII. Just add another zero byte to each ASCII character to convert to Unicode. Unicode contains over 20,000 Han characters, which are used to represent whole words or concepts in Chinese, Japanese and Korean. Unicode was developed by the Unicode Inc. consortium as a standard to replace the various proprietary 16- bit coding techniques which comprised two 8-bit bytes linked together. At the same time that Unicode was being developed, another standard was being developed jointly by the ISO and IEC. In 1992, the two coding schemes were linked to become what is known as both Unicode and BMP. See also BMP.


The transmission of information in one direction only.

Unidirectional Bus

A distribution conductor or set of conductors that can transfer information in one direction only.

Unidirectional Path Switched Ring

UPSR. A SONET transport method in which working traffic is transmitted in one direction. UPSR is preferred for interconnected rings with numerous signals crossing the rings.

Unified Messaging

Also called Integrated Messaging, universal messaging and unified communications (UC). You walk into your office in the morning. You turn on your PC and load up your messaging software, e.g. Microsoft Outlook. That's the software you typically use to receive and send emails. Only today, you notice that instead of seeing only emails awaiting your reading pleasure , you also see faxes and voice mails received by your telephone system. You can seem them all in one list. You can sort them by when you received them, or whom they're from or how big they are. You can click on your email and fax messages and read them on screen. You can click on your voice mail messages and hear them through your computer's speakers . Some unified messaging systems also allow you to call in and have your phone system read you your email messages, using text to speech, and, of course, listen to your voice mail messages over the phone or dialing in from afar. What's happened is that your company has acquired a server (big computer) whose job is to collect all your mail from its various places and consolidate them into one inbox. It may collect your email from various POP3 email servers (some distant and some local), from your fax server and from your voice mail server, which will be attached to your company's PBX telephone system. Once collected, it simply "serves" these messages up to you when you log in. See Integrated Messaging.

Unified Text Messaging

Under GSM cell phone systems (the ones common throughout the world) it's easy to send a message from one phone to another, irrespective of which carrier is providing wireless service ” so long as it's standard GSM. In the United States, where nothing is standard, most wireless carriers let their subscribers send short messages to and from phones served by that carrier. But sending messages from my phone to a phone on a different network is not easy nor even possible in most situations. If there comes a time when the U.S. carriers set up a system to allow short message service, instant messaging, or just plain messaging between cell phones from different carriers in the U.S., it will be known a unified text messaging.

Unified Voice

Unified voice is a bundled service that is provided via a T-1 line. It is designed to provide line side business telephone features similar to a LEC (Local Exchange Carrier) ” Hunting, call forwarding, voice mail, call waiting, call blocking and conferencing. The typical UV customer will not have a PBX but may have a key system at his offices. In the old days, they used to call unified voice Centrex, with the difference that unified voice also uses the Internet, where Centrex never did.

Uniform Call Distributor

UCD. A device for distributing many incoming calls uniformly among a group of people (typically called " agents " because of the early use of these machines by the airline, hotel and car reservation industry). These days the term Uniform Call Distributor is falling into disrepute as the newer term, Automatic Call Distributor comes in. According to incoming call experts, a Uniform Call Distributor is generally less " intelligent ," and therefore less costly than an ACD. A UCD will distribute calls following a predetermined logic, for example "top down" or "round robin ." It will not typically pay any heed to real-time traffic load, or which agent has been busiest or idle the longest. Also, a UCD's management reports tend to be rudimentary, consisting of simple pegs counts, as opposed to an ACD, which can produce reports on the productivity of agents.

Uniform Call Distributor

UCD. A device located at the telephone office or in a PABX that distributes incoming calls evenly among individuals; called a "call sequencer" in some non-Bell LECs.

Uniform Encoding

An analog-to-digital conversion process in which, except for the highest and lowest quantization steps, all of the quantization subrange values are equal.

Uniform Linear Array

An antenna composed of a relatively large number of usually identical elements arranged in a single line or in a plane with uniform spacing and usually with a uniform feed system.

Uniform Numbering Plan

A uniform seven-digit number assignment made to each phone in a private corporate network. Such a plan allows routing of calls to distant phones from any on-net telephone without any differences in the dialed number. Without a uniform numbering plan, you would dial your boss in New York differently if you were in the company's Chicago office and differently again if you were in your company's San Francisco office. With a uniform numbering plan, it would be the same from all locations. The nation's long distance network has, obviously, a uniform numbering plan.

Uniform Resource Identifier

URIs have been known by many names: WWW addresses, Universal Document Identifiers, Universal Resource Identifiers, and finally the combination of Uniform Resource Locators (URL) and Names (URN). As far as HTTP is concerned, Uniform Resource Identifiers are simply formatted strings which identify ” via name, location, or any other characteristic ” a resource on the Internet.

Uniform Resource Locator

URL. An Internet term. A standardized way of accessing various resources on the World Wide Web. In more technical terms, a URL is a string expression that can represent any resource on the Internet or local TC/IP system. The standard convention for a URL is as follows : method://host_spec {port} {path} {file} {misc} Here's an example of a URL. http://www.harrynewton.com. Typing those letters into your browser brings you to the opening screen ” or home page ” of my web site. In general http:// can be safely omitted with most browsers and you'll still get to the site. See URL for a detailed explanation. See also Uniform Resource Identifier.

Uniform Service Order Code


Uniform System Of Accounts

USOA. Part 3 of the FCC rules and regulations which prescribes names and numbers of accounts and describes the content of each account and gives rules for keeping records.

Uniform-Spectrum Random Noise

The laboratory name for "white noise," a test signal made of noise that is constant in its power for every unit of bandwidth; used to test the crosstalk characteristics of multichannel analog transmission systems.


See U-NII above.


Unimodem, the "Universal Modem Driver" for Windows 95 and now Windows NT Server 4.0 and Windows NT Workstation 4.0, is both a TAPI service provider and a VCOMM device driver. It translates TAPI (Windows Telephony API) function calls into AT commands to configure, dial, and answer modems. See AT COMMAND SET and UNI-MODEM V. See the following for Unimodem specifics:

Unimodem V

Unimodem stands for Universal Modem Driver. Unimodem V is Unimodem updated for voice. The V stands for voice, not five. It now replaces Unimodem. Unimodem stands for Universal Modem Driver. It is part of Windows 95 and Windows NT Server 4.0 and Windows NT Workstation 4.0. It is both a TAPI service provider and a VCOMM device driver. It translates TAPI (Windows Telephony API) function calls into AT commands to configure, dial, and answer modems. Unimodem V is the universal modem driver and telephony service provider for the Windows operating system. Included in Unimodem V are the features requested most often by users to support voice modems, including wave playback and record to/from the phone line, wave playback and record to/from the handset, and support for speakerphones, caller I.D., distinctive ringing and call forwarding. Unimodem now supports the most popular voice modems on the market. For Unimodem/V specifics:


Euphemism for being fired . Heard on the voicemail of a Vice President at a downsizing computer firm: "You have reached the number of an uninstalled Vice President. Please dial our main number and ask the operator for assistance." See also Decruitment.

Uninsured Traffic

Traffic within the excess rate (the difference between the insured rate and the maximum rate) for an ATM VCC. This traffic can be dropped by the network if congestion occurs.

Unintelligent Crosstalk

Crosstalk giving rise to unintelligent signals.

Uninterruptible Power Supply

UPS. A device providing a steady source of electric energy to a piece of equipment. A continuous on-line UPS is one in which the load is continually drawing power through the batteries, battery charger and invertor and not directly from the AC supply. A steady off-line UPS normally has the load connected to the AC supply. When the line is weak or down, it transfers the load without any user intervention. UPS are typically used to provide continuous power in case you lose commercial power. An UPS is typically a bank of wet cell batteries (similar to automobile batteries, but often much, much larger) engineered to power a phone system up to eight hours without any re-charging. A UPS system can also include a gasoline- powered generator. And if the generator works (make sure it has gas), you can power your phone system for much longer. According to Bell Labs, however, over 90% of all power outages last less than five minutes. The cost of Uninterruptible Power Supplies is typically a direct function of how large the battery/batteries are. The larger the batteries, the higher the cost. Many file servers on local area networks are also backed by UPSes. Many NetWare file servers, which are protected by a UPS, often are attached a printed circuit card inside the server. This card acts as an early warning system. When AC power drops , and the UPS takes over, it signals the file server through the card what has happened. The file server then will send a message to all the workstations on the network that the file server has lost AC power, is running on battery power, is running out and would everyone kindly log off the server. This protects the network.

Unipolar Signal

A two-state signal where one of the states is represented by voltage or current and the other state is represented by no voltage or no current. The current flow can be in either direction.

Unique Addressing

The addressing of a node by using the software-programmable address assigned to each one upon system initialization. For example, TELECONNECT's LAN has a "unique" addressing scheme. Each workstation is known by the operator's first name.

Unique Visitors

See Hit and Hits.


See Universal Service.


A European provider of Virtual Network Services (VNS). Unisource was created in 1994 by three European carriers: PTT Telecom Netherlands, Swiss Telecom PTT, and Telia of Sweden. Unisource provides a wide range of voice, data, and Internet services in a number of countries through its equity partners , as well as through a group of distributors. Distributors included AT&T-Unisource Communications Services, WorldPartners, and Infonet. The three equity partners merged their international networks in June 1997 into AT&T-Unisource Carrier Services (AUCS), which operates a fiber optic backbone running ATM. AT&T (except for AT&T UK) pulled out of Unisource in 1999, citing conflicts between AUCS and its Concert venture with British Telecom, but the name AUCS stuck. See also VNS.

Unit Interval

In a system using isochronous transmission, that interval of time such that the theoretical durations of the significant intervals of a signal are all whole multiples of this interval. The unit interval is the shortest time interval between two consecutive significant instants.

United States Telecom Association

USTA. See the next definition.

United States Telephone Association

USTA. Now called the United States Telecom Association. The largest trade association of telephone companies, with membership of over 1,200. USTA has its roots in the National Telephone Association, formed in 1897 to unite independent (non-Bell) telephone companies. Subsequently, the organization changed its name to the USITA (United States Independent Telephone Association). After the break-up of AT&T in 1984, the RBOCs (regional Bell Operating Companies) were admitted as members, and the name was changed to USTA, which now stands for United States Telecom Association. The organization, based in Washington, lobbies the FCC, Congress and other regulatory, legislative and judicial bodies to ensure that no regulations or legislation are passed to the detriment of its members. USTA also provides a little education for its members. USTA had a sister organization, the United States Telephone Suppliers Association, which is now merged with the EIA, forming the Telecom Association. www.usta.org. See the next definition.

United States Telephone Suppliers Association

USTSA. An association of suppliers ” manufacturers and wholesalers ” which originally was a committee of the United States Telephone Association (USTA). USTSA merged with EIA/ITG (Electronic Industries Association/Information and Telecommunications Technologies Group) in 1988 to form the TIA (Telecommunications Industry Association), which operates under the umbrella of the EIA. www.tiaonline.org and www.eia.org See also EIA, TIA and USTA.

Unity Gain

Refers to the balance between signal loss on a broadband network and signal gain through amplifiers .

Universal Access Number

A single number dialed from anywhere in the country which will route a customer to one or several locations for service, advice, etc. The definition varies depending on whose networking scheme you're dealing with.

Universal Addressing

The addressing of a node by the use of the universal addresses which all nodes recognize.

Universal Messaging

See Unified Messaging.

Universal ADSL

See ADSL Lite.

Universal ADSL Working Group


Universal Agent

A telephone agent who answers incoming calls and also makes outgoing calls. This duality feature may not seem worth of its inclusion in this dictionary. But the fact is that agents have largely been just "inbound" or just "outbound" ” because managers felt that most agents were not capable of doing both. The skills were, allegedly, too different. Now the idea is to " empower " the agent with more flexibility and make them "universal," i.e. capable of being used for both inbound and outbound.

Universal Asynchronous Receiver-Transmitter

UART. A device that converts outgoing parallel data from your computer to serial transmission and converts incoming serial data to parallel for reception . See UART for a bigger explanation.

Universal Character Set

UCS. A standard coding scheme developed in 1993, jointly by the ISO and IEC. See UCS for more detail.

Universal Circuit Card

See Universal Trunk Card.

Universal Device

A SCSA device. A call processing device which has every conceivable resource for the handling of calls. The SCSA programming applies resources from many different physical devices to a call processing task. These then act as if they were a single universal device.

Universal Digital Loop Carrier

A digital loop carrier system whose T-1 lines are powered by a digital channel bank, known as a central office terminal. The central office terminal interfaces with the switch (any type) through analog lines.

Universal Edge Server

MediaGate, San Jose, CA, defines a "universal edge server" as a new breed of Remote Access Server (RAS) that offers telephony functionality combined with traditional data remote access capabilities. Such Universal Edge Server allows user to combine voice, email and pager communications into a single, secure message box, accessible via phone, fax, web browser or email client.

Universal International Freephone Number


Universal Mailbox

Allows a user of unified messaging services to have single access to all messages from internal and external electronic mail systems, fax systems and voice mail systems. A really neat idea given today's lack of standardization among electronic mail services.

Universal Messaging Universal Name Space

The set of all unique object identifiers in a domain, network, enterprise, etc. Object naming standards and methods for locating and sending messages to mobile objects are required in large-scale object-oriented distributed-computing systems.

Universal Night Answer

A feature of telephone systems that permits any phone to pick up any incoming trunk call when the Attendant's console is unmanned (unpersonned?) and the phone system is set up (typically at the console) for "Night Answer."

Universal Pay Phone

Description for a coin-and-credit-card phone.

Universal Personal Telecommunications

UPT. The ITU (formerly CCITT) term for the wired network architecture and capabilities to support PCS.

Universal Plug and Play

Microsoft's answer to Sun's Jini. See Jini.

Universal Ports

A modern telephone system is typically an empty cabinet into which you slide printed circuit cards. Those cards have an edge connector and they slide into a connector at the rear of the cabinet. That connector connects via wires to other connectors in what is typically called the phone system's bus. In the old days, phone systems had dedicated slots ” meaning you could only slide one type of printed circuit card into that particular slot. As phone systems got more advanced, they acquired "universal ports." Our definition of a universal port is that all the slots are totally flexible ” namely that you can slide any trunk or phone card (either electronic or single line phone) into any slot in the phone system. The advantage of this is obviously a far more flexible phone system, able to accommodate lots of phones and few trunks or vice versa.

Universal Power Supply

A power supply which you can plug into electricity ranging from 100 volts to 240 volts AC. With a universal power supply (now standard with many laptops) you can travel the world, plugging yourself into virtually any power outlet and have your device work perfectly , without the need for a transformer. What you'll need, however, is a plug that converts the plug you have into the necessary plug for that country. Such a converter plug shouldn't cost you more than $2.

Universal Resource Locator

See Uniform Resource Locator.

Universal Sender

Allows the dialed number to be sent out by the user.

Universal Serial Bus

See USB.

Universal Service

Milton Mueller of Syracuse University observes that universal service policy has gone through two generations:

  1. First generation (1907 - 1965),

  2. Second generation (1965 - present). The first generation was about connecting competing networks into "one system, one policy, universal service." This was the Theodore Vail vision. Vail was the first president of AT&T. The second generation started after World War II. As a response to political pressures, regulators decided to keep local rates low using the surplus generated by long distance. This system of cross-subsidies was threatened by the rise of long distance competition in the 1960s and early '70s. That was a shock to telephone monopolies because it meant that long distance rates were about to go down and therefore the subsidies were about to decline. Telephone companies tried to defend their monopoly privileges by claiming that cross subsidies were essential to the preservation of widespread household telephone penetration. This way, the term "universal service" was dusted off by the monopolies and got a new meaning: a telephone in every home (universal service as we understand it today).

Now for some history: The Communications Act of 1934 defined the nation's telecom goal as "To make available, so far as possible, to all the people of the United States a rapid, efficient Nationwide, and worldwide wire and radio communication service with adequate facilities at reasonable charges." The same act created the FCC (Federal Communications Commission), charging it with the responsibility to carry out this policy, as well to regulate the telecommunications industry, in general. Prior to the breakup of the Bell System in early 1984, AT&T and the BOCs (Bell Operating Companies) administered a fund through the "settlements" process, which essentially reimbursed the LECs (Local Exchange Carriers) for the use of their local networks in originating and terminating long distance calls. "High cost" (i.e., rural) LECs were compensated at very high levels, in recognition of the universal service policy. Since 1983, NECA (National Exchange Carrier Association) has been charged with this responsibility.

The Telecommunications Act of 1996 considerably expanded the definition of "universal service" to include "access to advanced telecommunications and information service...in all regions of the Nation, including low-income consumers and those in rural, insular, and high cost areas...reasonably comparable to those services...and those rates...for similar services in urban areas." The Act goes on to provide for discounts to elementary and secondary schools and classrooms, health care providers, and libraries. The Telecommunications Act of 1996 also directed that a special Universal Service Joint Board comprised of federal and state regulators and a consumer advocate develop recommendations for the FCC identifying services that will be supported by a federal universal service funding mechanism. Relying heavily on the Joint Board's November 8, 1996, Recommended Decision, the FCC released a Report and Order that undertakes to modernize universal service policy in an increasingly competitive marketplace and to fundamentally expand its applicability. See also FCC, High Cost, NECA, Separations and Settlements and Universal Service Fund. See also www.fcc.gov/ccb/universal_service/welcome.html and www.ntia.doc.gov/opadhome/uniserve/univweb.htm

Universal Service Administrative Company

USAC. The not-for- profit corporation set up and operated by NECA (National Exchange Carriers Association) to administer the Universal Service Fund (USF). USAC accepts the Universal Service funds collected by the LECs (Local Exchange Carriers) and IXCs (IntereXchange Carriers), and disburses them in support of Universal Service (US). Universal Service first was stated as a national United States objective in the Communications Act of 1934, with the idea being that all U.S. citizens should have access to basic telephone service of good quality and at reasonable cost, regardless of where they live, and regardless of the underlying cost to the LEC of providing such service. That translated into a complex set of cross-subsidies administered by the FCC (Federal Communications Commission), which was formed by that very same act. Universal Service finally was codified (made into law) with the Telecommunications Act of 1996 (The Act), and the fund was formalized to support universal service in high-cost areas. The Act also led to the formation of USAC and its three divisions, The High Cost and Low Income Division, The Schools and Libraries Division (SLD) and the Rural Health Care Division (RHCD). The first division is responsible for disbursement of funds in connection with the original stated purposes of the USF. The last two divisions are responsible for the disbursement of funds to ensure that funds are made available to their respective constituencies to subsidize the cost of inside wiring, telecommunications services, and Internet access, with the ultimate objective being that of ensuring that all US citizens can participate in the Information Age. See also FCC, Telecommunications Act of 1996, Universal Service, and Universal Service Fund.

Universal Service Charge

A federal subsidy program that is apparently apprently being widely abused. The idea is that phone companies would add a figure to their bill, of apparently 6.9 percent. But some of the long distance companies are charging up to 12 percent. And the FCC seems to have little clue, according to testimony, where the extra money is going ” though it's obviously adding to the carriers' income. See Universal Service Fund.

Universal Service Fund

USF. Under the direction of the FCC, the National Exchange Carriers Association (NECA) administers the USF, which is a cost allocation mechanism designed to keep local exchange rates at reasonable levels, especially in "high cost" (i.e., rural) areas. The primary support mechanism that applies to telecom carriers is the high cost Support mechanism, of which there are five main components:

  1. High-Cost Loop Support, Compensates rural operators for the cost to build local loops in areas where the cost exceeds 115% of the national average.

  2. Local Switching Support. Interstate support to cover switching costs for companies that serve fewer than 50,000 customers.

  3. Long-Term Support. Distribution of interstate access charges for rate-of-return- regulated operators. A new universal support mechanism, Interstate Common Line Support, was created under the MAG plan (discussed below) to convert implicit subsidies to explicit subsidies.

  4. High Cost Support for Non-Rural Carriers. Compensates rural operators for the cost to build the local loop in areas where the cost exceeds 135% of the national average.

  5. Interstate Access Support. Distribution of interstate access charges for price cap regulated operators. The CALLS plan, which was passed in 2001, established an explicit support mechanism capped at $650 million for such charges.

NECA administers the program by collecting USF data, determining LEC eligibility, billing the IXCs (long distance phone companies), and distributing the payments. The original goal of the Universal Service Fund was to provide at least one access line for basic telephone service to every household in the U.S., and at a reasonable, subsidized cost. The fund gets money from a surcharge on phone lines, and uses those funds to offset operating costs of telcos in high-cost areas. While the concept of Universal Service was first stated in the Telecommunications Act of 1934, and while the USF has been in place for a great many years, it wasn't codified (enacted into law) until the Telecommunications Act of 1996 (The Act). The Act changed the underlying subsidy mechanism, authorizing the carriers to add a surcharge of up to five percent onto every telephone bill. The Act also established two new not-for-profit corporations, which now operate as divisions of the Universal Service Administrative Company (USAC), a not-for-profit corporation operated by NECA. The Schools and Libraries Corporation (SLC), which operates as the Schools and Libraries Division (SLD), is funded to the tune of up to $2.25 billion per year. The Rural Health Care Company (RHCC), which operates as the Rural Health Care Division (RHCD), is funded to the tune of $400 million per year. The funds are parceled out by these divisions to help fund necessary inside wiring, telecommunications services, and Internet access. See also FCC, NECA and Universal Service.

Universal Service Obligation

See USO.

Universal Service Order Code

USOC. The information in coded form for billing purposes use by the local telephone company pertaining to information on service and equipment (S&E) records. USOCs are not truly "universal," as operating companies can have wide differences in terminology. For example, a flat-rate single-party residence line is known variously in USOC terminology as 1FR and FR1.

Universal Service Plan

See USP.

Universal Trunk Cards

Most PBXs have different circuit boards (or circuit cards - same thing) for combination trunks and for DID (direct inward dial) trunks. A Universal Circuit Board enables you to use the ports on the board for either combination trunks OR DID trunks. This capability makes the PBX more flexible. If you have spare ports on a trunk circuit board you may use them for either a combination or a DID type of trunk.

Universal Turret

A very large key system for financial traders, emergency teams at nuclear power stations and others who need single phone button access to hundreds of people. By simply pushing one of the button in front of them, the user can dial one of hundreds of people. These buttons may be connected to tie lines, foreign exchange lines. They may even be DDD lines with autodial capability. Like all good key systems, the buttons have a lamping display which shows if the particular line is idle, busy, ringing, on hold, etc.

Universal Wall Jack

There's really no such animal. Every manufacturer of installation gadgetry is trying to propagate the idea that their jack is universal, when it really isn't. The "universal" wall jack we installed in our new offices is actually four jacks ”

  1. Four pairs for two PBX voice lines (one electronic two-pair phone and one tip and ring phone) and one spare.

  2. One RS-232-C 12-conductor shielded cable for connecting to centralized printers, for connecting to a dataPBX and for permanent null-modem connection of computers.

  3. One for connecting to our high-speed, one megabit per second LAN, and

  4. One spare twisted, shielded, stranded pair for a second LAN, or whatever comes along.

Universal Wireless Communications Consortium

UWCC. A consortium of over 100 wireless telecommunications carriers and vendors dedicated to promoting and supporting TDMA (Time Division Multiple Access) cellular phone service. TDMA competes with FDMA (Frequency Division Multiple Access), the analog cellular approach, and CDMA (Code Division Multiple Access), another digital approach. Specifically, the UWCC promotes TDMA as a platform for developing and delivering enhanced personal communications features through the TIA's (Telecommunications Industry Association's) IS-136 (Interim Standard-136) for the TDMA digital air interface, and the IS-41 Wireless Intelligent Network (WIN) internetwork standard. The attempt is to bring together the three primary versions of TDMA RF (Radio Frequency) technology. GSM (Global System for Mobile Communications), is the European version. PHS (Personal Handyphone Service), also known as PDC (Personal Digital Cellular), is the Japanese version. IS-136 is the North American version, which allows AMPS (Advanced Mobile Phone System) to coexist with TDMA on the same network, sharing frequency bands and channels. GSM, PHS, and IS- 136 are incompatible, meaning your phone which works on one of these networks won't work on the other networks. The UWCC also is involved heavily in the promotion of 3G (3rd Generation) TDMA-based wireless standards, including EDGE (Enhanced Data Service for GSM Evolution), GPRS (General Packet Radio Service), and UMTS (Universal Mobile Telecommunications System). See also CDMA, Cellular, EDGE, FDMA, GPRS, GSM, IS-41, IS-136, PHS, TDMA, UMTS, and WIN. www.uwcc.org.


A call center term. The total number of names to be attempted on an outbound call program.


An immensely powerful and complex operating system for computers for running data processing and for running telephone systems. UNIX was developed in 1969 by Ken Thompson, Dennis Ritchie and a few other programmers at Bell Telephone Laboratories. They had been working on the MULTICS (MULTiplexed Information and Computing System) project, a multiuser time-share system development project sponsored by MIT, Bell Labs and General Electric. Thompson then began to develop UNICS (a single-user variant on MULTICS) on an old DEC PDP-7 minicomputer he scrounged. According to legend, Thompson wanted to play Space War, an early computer game. In 1973, Thompson and Dennis Ritchie rewrote UNICS in the high-level C programming language, which is extremely portable, offering the incredible advantage of allowing programs to transition smoothly to newer computing platforms over time. At that point, UNICS became known as UNIX. The "X" in "UNIX" signifies that it can run on just about any computing platform. (Note: "X" is the generic "whatever.")

UNIX provides multi-tasking, multi-user capabilities that allow both multiple programs to be run simultaneously and multiple users to use a single computer. On a single-user system, such as MS-DOS, only one person at a time, on an individual task basis, can use a computer's files. programs, and other resources. Later Windows versions of MS-DOS added multi-tasking capabilities, of course. Today, the UNIX operating system is available on a wide range of hardware, from small personal computers to the most powerful mainframes, from a multitude of hardware and software vendors. UNIX is also a trademark of UNIX Systems Laboratories, Inc. which used to be owned by Novell Inc. but then was sold to SCO, Santa Cruz Operations. UNIX has given rise to a number of variants, including AIX from IBM, HP-UX from Hewlett-Lackard, LINUX, POSIX from the US government, Solaris from Sun, and ULTRIX from DEC. See also LINUX and MULTICS.

UNIX-To-UNIX Copy Program

UUCP. A standard UNIX utility for exchanging information between two UNIX-based machines in a network. UUCP may also be referred to as the UNIX-TO-UNIX Communications Protocol and is widely used for electronic mail transfer.

unknown device

A Bluetooth term. A device that is currently not connected with the (LocDev and the LocDev has not paired with it in the past. Also called a new device. No information about the device is stored (e.g., BD_ADDR, link key, or other information).

Unlicensed bands

There are two types of wireless communications devices. Those that require a licence from the Federal Communications Commission. And those that don't. Those that require a license run in a licensed communications band, a specific frequency. Those that don't require run in unlicensed communications bands can be plugged in and run ” so long as they meet FCC rules for that communications band, i.e. that frequency. The FCC's rules loosely prohibit " harmful interference" of unlicensed devices, but devices that run in an unlicensed band are not guaranteed protection from interference.

Unlicensed PCS

Unlicensed PCS is the name for wireless frequency in the PCS band, which in the United States is 1.920 GHz - 1.930 GHz. The advantage of unlicensed PCS is that you can install a wireless telephone system in your company in this band without having to secure licenses from the Federal Communications Commission. Such systems are often called "business wireless." Such systems are typically all digital and often hang off a PBX. And the wireless phones often will have most of the features that an electronic phone wired to the PBX would have.

Unlisted Number

There are various interpretations of what constitutes an "unlisted, an "unpublished" or a "non-published" phone number in North America. Some phone companies use these words interchangeably. Some don't. In California, Pacific Bell offers unpublished phone service. Your phone number is not listed in the paper phone directories, but is listed with dial up "Directory Assistance." Pacific Bell also has a more expensive service called "Unlisted Service." Here, your phone number is not included in the paper phone directories or given out to callers to Directory Assistance. Telephone companies have a service whereby you can leave a message for the owner of an unlisted number. "Please call me. You've won the lottery." The owner of the unlisted number then has the choice to return the call or not. He doesn't pay to receive this message. Some telephone companies confuse the definitions and some invent new ones. For example, some phone companies use the term "non-published" number. You won't find the number in a phone book or by calling Directory Assistance. Over 25% of many private phone numbers in major metropolitan areas are unlisted, unpublished or non-published ” a "service" their subscribers pay extra for. To my simple brain, it's a lot easier to simply publish your name as "Apple Plumpudding." See Unpublished.

Unloaded Line

A telephone line with its loading coils removed to increase the distance and speed with which data may be transmitted over the line. A fee is usually charged for removing the coils.

Unlock Code

This is a three-digit number required to unlock a cellular phone when you have electronically locked it to prevent unauthorized use. You might lock it when you park your car in a hotel. The factory default is 123.


Unified Network Management Architecture. AT&T's proprietary architecture for network management.

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

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