Telephone Manager-Token Latency

Telephone Manager

Apple's telephony API for the Macintosh world. Here is an excerpt from Apple's Web page explaining it : "Telephony is the process of managing telephones, particularly of establishing and controlling connections between telephones on a telephone network. The Telephone Manager is the part of the Macintosh system software that you can use to develop applications and other software that provide telephony capabilities. For example, you can use the Telephone Manager to place outgoing telephone calls, answer incoming telephone calls, place calls on hold or transfer them to other telephones, and accomplish many other similar tasks . The data transferred during a telephone call can be either voice, modem, or fax data, or indeed any kind of data that can be encoded for transmission across a telephone network.

"The Telephone Manager provides a set of simple but powerful programming interfaces that you can use to support telephony activities. The Telephone Manager operates independently of the particular telephone network or networks to which a user 's computer is connected. Accordingly, your application can provide telephony services whether the Macintosh computer on which it is executing is connected to an integrated services digital network (ISDN), to a private branch exchange (PBX), or to "plain old telephone service" (POTS).

"The Telephone Manager accesses a specific telephone network using a telephone tool, a software module that manages the connection between a network and the telephony applications or other software running on a Macintosh computer. Telephone tools control the device drivers of the telephony hardware (such as an ISDN card) installed on the user's system. Each telephone tool is designed for specific hardware. For example, the Apple ISDN Telephone Tool is designed for the Apple ISDN NB Card. For more, or

Telephone Pioneers of America

The Telephone Pioneers of America began almost a century ago, originally consisting of the 'charter employees ' of the company, or 'pioneers' in telecommunications, mainly those who served with the Bell System at its outset. As time went on, there would be fewer living or active original Pioneers, thus the TPA charter was amended to allow membership by any employee of AT&T or (as they were called) a subsidiary company who had been employed by Bell (or an independent) for at least twenty years. Membership in the Pioneers was opened to more types of telephone company people over the years (including companies that are not "Bell" or AT&T).

The Telephone Pioneers have a distinguished history of community service. Pioneers devise technical solutions to improve the lives of those with disabilities , allowing them to use telephones when this would otherwise be difficult or impossible . Pioneers also assist with general community activities such as voter registration, help those who are ill, feed those who are needy, and more. The Telephone Pioneers of America has chapters throughout the USA and Canada. At the non-Bell telcos, the same organization is known as the Independent Pioneers.

Telephone Plant Index

TPI. The telecommunications indicator used to calculate inflation based on a "Market Basket of Goods."

Telephone Preference Service

TPS. A service offered by the Direct Marketing Association, New York, NY. The DMA keeps a list of consumers who have requested that their names be removed from telemarketing calling lists. Telemarketing companies can have the list upon request. Use of the service does not relieve companies from their obligation under the TCPA. In Europe the TPS is called a Robinson List.

Telephone Receiver

Telephone earpiece. Device that converts electrical energy into sound energy, designed to be held to the ear.

Telephone Relay Service

TRS. A voice/data system that enables communications with the hearing impaired.

Telephone Number

The Telephone Number is officially the 10-digit number (613-723-8231) of that subscriber, hence it includes the area code. See DN.

Telephone Number Salary

A salary that has seven digits, based on the fact that local North American phone numbers have seven digits.

Telephone Service Representative

TSR. Another word for agent ” the person who answers the phone on an automatic call distributor. See Agent.

Telephone Set

A fancy name for a telephone.

Telephone Set Emulation

The concept is simple: Emulate the proprietary electronic phone on a printed circuit card inside a PC. Let the PC do everything a human using the phone could do. Only the PC will do it more efficiently and the human will find it easier to use all his phone's features because the PC's screen is bigger and the PC's keyboard easier to use than the phone's keyboard. Attach the phone emulation card to voice and call processing cards, like voice synthesis, voice recognition, voice mail, touchtone generation and recognition, etc. And bingo, phone systems acquire all the benefits of integrated voice and call processing. It's powerful concept. As I wrote this, a handful of telephone phone emulation cards had appeared. Within a little while, there won't be a phone worldwide that you won't be able to emulate on a printed circuit card you can drop into a vacant slot inside your PC.

Telephone Set Management

Imagine you have a phone attached to your computer through a telephony board inside your computer. Now imagine that you pick up the phone and dial a number. If the company knows you have dialed a number and knows which number you have dialed , that feature is called handset management. It is the ability of the computer to be aware of every button pushed on the phone. The advantage of this is obvious: You really want the PC to collect those digits, so it can, for example, add a price to each call and use them for monthly billing (lawyer, accountant , etc.). You also want to be able re-dial those numbers by simply clicking on the number one you want, hitting Enter and bingo, you're redialing that number, without having to key it in again. This term , telephone set management, used to be called handset management.

Two of the early pioneers in the field of telephone set management, David Perez and Nick Nance of COM2001 Technologies in San Diego, defined telephone set management as "the ability for seamless Integration with the phone (any 2500 set) and the modem / voice processing board and /or fax machine. The hardware must notify (send a signal or command) to the software when the phone is off hook or on hook. It must also notify the software when the user presses the numeric buttons on the phone. Ultimate integration would include additional types of button support as in: volume, hold, release, redial, conference, or any button on the telephone / fax / modem etc. The reason? Telephone integration offers true Computer Telephony integration. The ability to signal the handset and feature keys allows the user to continue to use their desktop phones but take complete advantage of the Computer Telephone software on their desktop for speed dialing, transferring, conferencing, voice mail, etc.

Telephone Signaling Device

A gadget which indicates that the phone is ringing. May also be hooked up to lamps or overhead lighting to cause those lights to flash when the phone is ringing.

Telephone Tag

I call you. But you're not there. I leave a message. You call me back. But I'm not there. You leave a message. And so on. We're now playing telephone tag.

Telephone Tap

Telephone taps are generally defined as devices which are designed to extract audio information of intelligence from the telephone line pair. The process consists of identifying the specific telephone talk pair of interest at some accessible point, the interception of their electrical signals, and the communication of these signals to the surveillance equipment operator. Telephone companies unintentionally assist the wiretapper by installing extra telephone wires for future expansion. There are almost always extra wires that can be appropriated for use in wiretapping.

Wiretaps can be installed at the telephone company's central office if the phone company cooperates. If not, taps can be installed in splice cases or in a ready access terminal. Wiretaps should be distinguished from telephone bugs. Bugs are room audio surveillance devices that use the telephone wiring to bring the audio to the surveillance operator. Telephone bugs are used because they avoid RF interference.

Telephone Tone

Audible tone generated by the network which provides call progress indications to the user. Different tones (e.g., ring back, busy) allow the human ear to interpret the progress of the call. On digital networks (such as PBX or ISDN), the network may send indication messages (e.g., billing, carrier, faxCNG, modemCNG) to the telephone to indicate the status of the call, and the telephone may generate certain tones locally, driven by those messages.


This is a European term referring to what North America calls a receptionist or switchboard attendant Note: the term switchboard operator is also used in Europe, but not switchboard attendant.


The science of transmitting voice, data, video or image signals over a distance greater than what you can transmit by shouting. The word derives from the Greek for "far sound." For the first hundred years of the telephone industry's existence, the word telephony described the business the nation's phone companies were in. It was a generic term. In the early 1980s, the term lost fashion and many phone companies decided they were no longer in telephony, but in telecommunications ” a more pompous sounding term that was meant to encompass more than just voice. The pomposity of the word may have added some value to the stock of telecommunications companies. In the early 1990s, as computer companies started entering the telecommunications industry, the word telephony was resurrected. And in a white paper on Multimedia from Sun Microsystems, the company said that telephony refers to the integration of the telephone into the workstation. For instance, making or forwarding a call will be as easy as pointing to an address book entry. Caller identification (if available from the telephone company) could be used to automatically start an application or bring up a database file. Voicemail and incoming faxes can be integrated with e-mail (electronic mail). Users can have all the features of today's telephones accessible through their workstations, plus the added benefits provided by integrating the telephone with other desktop functions. See also Computer Telephony.

Telephony Access Module

See TAM.

Telephony Interface Control

A Telephony Interface Control resource is any resource that interfaces with the telephone network (public or private). This is usually claimed as the primary member of a group .

Telephony Markup Language

Telephony Markup Language (TML) is a vocabulary extension to the Extensible Markup Language (XML) dealing with telephony, unified messaging, and other forms of network data exchange. Thanks to efforts by the World Wide Web Consortium (W3C), XML itself recently became a formal specification. Like HTML, XML is a simplified descendant of the enormously complex Standardized General Markup Language (SGML) that's been used for high-end, highly structured publishing applications for the last ten years. But unlike HTML, XML allows you to create your own tags (which is what "extensible" means). Whereas HMTL is concerned primarily with presentation, XML tags ” which can exist on the same page as HMTL ” specify content (first name, price, phone number, etc.).

The idea for TML originated with Computer Telephony Magazine editor-in-chief John Jainschigg. Two companies were instantly excited about developing and building TML into their products: SoloPoint (Los Gatos, CA) and Technology Deployment International (Santa Clara, CA). These and other companies are contributing to the TML initiative by atomizing call and messaging functions in an effort to start formulating a list of possible telephony and messaging tags. The telephony tags will be a universal way to put touchtone screens on browser-equipped handheld devices, and since XML will become a standard mechanism for exchanging data as well as documents, it's possible that voice mail, video mail, faxes and email messages from different vendors ' repositories could be exchanged across the Internet and reviewed on any XML compatible device.

But TML will be more than just standardized tags for telephony and unified messaging. While XML definitely will be appearing on browsers, you can think of XML (and TML) as more of a self-describing messaging standard rather than simply some extra tags focusing on web page content. XML can be used on the Internet, intranet, extranet, VPNs, WANs, or whatever, because XML itself is not actually sending messages. XML describes the message content while other applications, components or servers actually send and interpret the messages containing XML.

So TML should not be thought of as merely a "browser client-like thing" talking to a "server-like thing." TML will be a more pervasive messaging environment running over all networks.

The closest thing to being a TML competitor is VxML or "VoxML," sponsored by some big companies such as Lucent and Motorola. VxML is a XML language for voice menu item management. It's used to represent a caller's many choices and input options when interacting with an IVR or other voice automation system. But like the TML developers, the VoxML developers (some ex-Bell Labs guys) look upon the client not just as a browser but as "audio over any phone" which makes sense for an IVR- related XML language. Still, the industry needs something more powerful and comprehensive than VxML, which is what TML's supporters hope it will be.

Telephony Server

A telephony server is a computer whose major function is to control, add intelligence, store, forward and manipulate the various voice, data, fax and e- mail calls flowing into and out of a computer telephony system. The traditional function of a telephony server is to move call control commands from client workstations on a LAN to an attached PBX or ACD. (This is what it does under the paradigm called "Telephony Services.") A telephony server can also be a voice response system. It can also be a fax on demand system. It can also be a conferencing device. It can also be switch. And it can be all these capabilities, which traditionally run on physically separate servers, all rolled into one machine, called generically a "telephony server." See Telephony Service Application Programming Interface And Telephony Services.

Telephony Services Application Programming Interface.

TSAPI. Described by AT&T, its inventor , as "standards-based API for call control, call/device monitoring and query, call routing, device/system maintenance capabilities, and basic directory services." For a better explanation, see Telephony Server, Telephony Server NLM and Telephony Services.

Telephony Server NLM

Telephony Server NetWare Loadable Module. The main part of a software product call Telephony Services announced in early 1993 by AT&T and now marketed by Lucent (but not Novell). The Telephony Server NLM is software add-on to Novell's NetWare LAN operating software. The idea is have a NetWare server equipped with the NLM, an interface card and a cable connection to an adjoining telephone system. This would mean that anyone with a PC on the network and a PBX phone on their desk will be able to use telephone features, such as auto-dialing, conference calling and multiple call handling from their desktop PC.

A Novell White Paper in Spring of 1993 said "Telephony Services for NetWare provides benefits to three main customer segments. First, applications are being developed to provide increased productivity to everyday computer desktop users. Second, call-centers take advantage of this technology as it provides a right-sizing cost-effective solution. Finally, benefits will be available to telecommunications/IS administrators by providing the ability to reduce administrative costs through easier management of user databases.

"Computer-Telephone Integration (CTI) combines telephone and computer technology to provide access and control telephone functionality from a computer terminal. It combines the easy access and usable graphical interface of the computer desktop with the features of the telephone. CTI is not a new concept. Traditionally, however, CTI has only been available in a mini and mainframe computer environments. These solutions are expensive and can be cost-justified only in large call-center applications. Consequently, the penetration of CTI solutions has been very small.

"However, providing CTI in NetWare environment brings this technology mainstream. Not only does this solution provide a more cost-effective implementation, it also allows integration with the rich set of NetWare services. In the simplest example, a Telephony Services for NetWare application allows users to make a phone call by clicking on a name from a calling list displayed on a desktop computer and having the desktop computer dial the number. Possibilities exist for applications that will allow similar functionality with the addition of conference calling capability. Instead of clicking on a single name, the user can highlight a number of names, click on a conference-call icon and have the system place the calls to all parties. The benefits which are derived from the integration of telephony with other NetWare services is far reaching. As part of continued development efforts, applications are becoming available which allow desktop video phone calls. Callers can see each other and talk on the phone, while simultaneously viewing and editing image documents.

"Other capabilities include integrating voice-mail , fax and e-mail into a single message- management application. Possibilities also exist utilizing number recognition technology to integrate computer database records with caller-id . Administrators can manage a single user database utilized by the computer network, the PBX and the voice-mail system.

"Telephony Services for NetWare takes advantages of client/server technology to provide a broad framework for creating first-party and third-party call-control applications. These applications answer the customer demand for integrated business tools and solutions. This technology provides a logical connection between the desktop computer and the telephone. The only physical connection is established between the PBX and a NetWare server. This architecture is cost-effective and efficient by utilizing a company or organization's existing equipment. The initial product deliverables include the following components:

  • Client/Server API

  • Telephony Server NLM

  • PBX Driver

  • PBX Link Hardware

  • Passageway Application "The Telephony Server NLM is the mechanism for passing information between the PBX and the NetWare server. As part of the NLM, an open PBX Driver Interface allows PBX manufacturers to write drivers which communicate with their respective PBX models. The client/server API provides support across multiple desktop operating systems. It also allows call control at either the client or the server. The Passageway application provides the user with basic autodialing and notes capability.

"Telephony Services for NetWare provides a key opportunity for developers. Open APIs which support multiple desktop operating systems provide a development platform for both traditional telecommunications developers and new or experienced NetWare developers."

Novell has effectively stopped marketing Telephony Services, but AT&T (now Lucent) continues to market it. See Telephony Services.

Telephony Service Provider

TSP. A software encapsulation of all the services provided by a particular network interface device or line device. A line device may be a single POTS bearer channel or it may be several bearer channels; e.g., a single E-1 span with 30 network channels of 64 Kb/s bandwidth. The TSP is provided by the vendor who has developed a network interface device for SCSA. See S.100.

Telephony Services

Telephony Services' real name is Telephony Services for NetWare, the local area network software from Novell, Orem, Utah. Telephony Services for NetWare basically consists of an addition to the NetWare operating system, called Telephony Server NLM. (See Telephony Server NLM.) That addition handles communications between a NetWare file server (a PC loaded with NetWare) and an attached telephone switch, e.g. a PBX or ACD (automatic call distributor). The concept is very simple. Picture your depart- ment's LAN. You're sitting in front of your PC which is on your department's LAN. You have a telephone which is an extension off your company's or department's PBX. You click on an icon that says "Phone." Bingo, a screen comes up with icons and pull down menus . You can now look up Joe, click on his name. Your PC sends a command to your NetWare file server, which in turn sends a command to your PBX which tells it to dial Joe from your phone. Once it's completed dialing, it might turn on your phone's speakerphone or your telephone headset. You'll then hear Joe say "Hello." Telephony Services for NetWare is basically the software in the NetWare file server which takes care of interpreting your PC commands into commands your switch can understand and respond to.

Telephony Services requires a link to your switch. Each telecom switch manufacturer has been implementing that link in a different way technically. That's fine, because Telephony Services for NetWare insulates the user and the developer. This means that computer telephony applications written for Telephony Services for NetWare will work on any switch conforming to the Telephony Services standard. As of writing, virtually every switch manufactured in North America and many made in Japan and Europe is conforming to Novell's Telephony Services.

According to a White Paper issued by Novell in March 1994 and called NetWare Telephony Services, "The three main components of Telephony Services are call control, voice processing, and speech synthesis. Call control provides the core service for PBX-to- NetWare communication and an Application Programming Interface (API) for developing client server applications. With call control, users can enjoy features, says Novell, such as making calls, transfers, or conference calling. Voice processing functions include voice mail and interactive voice response. Speech synthesis will be a key area for integrating multiple media types. Through speech/text conversion, users can access voice mail, e-mail, and fax documents through audio or text media types. The initial products Novell is delivering include:

"Client/Server API

"Telephony Server NetWare Loadable Module (NLM)

"PBX Driver

"The Telephony Server NLM is the mechanism for passing information between the PBX and the NetWare server. As part of the NLM, an open PBX Driver Interface allows PBX manufacturers to write drivers that communicate with their respective PBXs. The client/server API provides support across multiple desktop operating systems and allows call control at either the client or the server."

Client server computer telephony, according to Novell, delivers ten benefits:

  1. Synchronized data screen and phone call pop. Your phone rings. The call comes with the calling number attached (via Caller ID or ANI). Your PBX or ACD passes that number (via Telephony Services) to your server, which does a quick database look up to see if it can find a name and database entry. Bingo, it finds an entry. It passes the call and the database entry simultaneously to whoever is going to answer the phone: The attendant. The boss. The sales agent. The customer service desk. The help desk. All this saves asking a lot of questions. Makes customers happier .

  2. Integrated messaging. Also called Unified Messaging. Voice, fax, electronic mail, image and video. All on the one screen. Here's the scenario. You arrive in the morning. Turn on your PC. Your PC logs onto your LAN and its various servers. In seconds, it gives you a screen listing all your messages ” voice mail, electronic mail, fax mail, reports , compound documents .... Anything and everything that came in for you. Each is one line.

    Each line tells you whom it's from. What it is. How big it is. How urgent. Skip down. Click. Your PC loads up the application. Your LAN hunts down the message. Bingo, it's on screen. If it contains voice ” maybe it's a voice mail or compound document with voice in it ” it rings your phone (or your headset) and plays the voice to you. Or, if you have a sound card in your PC, it can play the voice through your own PC. If it's an image, it will hunt down (also called launch) imaging software which can open the image you have received, letting you see it. Ditto, if it's a video message.

    Messages are deluging us. To stop them is to stop progress. But to run your eye down the list, one line per entry. Pick the key ones. Junk the junk ones. Postpone the others. That's what integrated messaging is all about. Putting some order back into your life.

  3. Database transactions. Customer look ups. There are bank account balances , ticket buys, airline reservations , catalog requests , movie times, etc. Doing business over the phone is exploding. Today, the caller inputs his request by touchtone or by recognized speech. The system responds with speech and/or fax. Today's systems are limited in size and flexibility. The voice processing application and the database typically share the same processor, often a PC. Split them. Spread the processing and database access burden . Join them on a LAN (for the data) and on new, broader voice processing "LANs," like SCSA or MVIP. You've suddenly got a computer telephony system that knows no growth constraints. You could also get the system to front-end an operator or an agent. Once the caller has punched in all his information, then the call and the screen can be simultaneously passed to the agent.

  4. Telephony work groups. Sales groups. Collections groups. Help desks. R&D. We work in groups. But traditional telephony doesn't. Telephony today is BIG. Telephony today is one giant phone system for the building, for the campus. Everyone shares the same automated attendant, the same voice mail, the same ubiquitous, universal, generic telephone features. But they shouldn't. The sellers need phones that grab the caller's phone number, do a look-up on what the customer bought last and quickly route the call to the appropriate (or available) salesperson. The one who sold the customer last time. The company's help desk needs a front end voice response system that asks for the customer's serial number, some indication of the problem and tries to solve the problem by instantly sending a fax or encouraging the caller to punch his way to one of many canned solutions. "The 10 biggest problems our customers have." When all else fails, the caller can be transferred to a live human, expert at diagnosing and solving his pressing problem. A development group might need e- mails and faxes of meeting agendas sent, meeting reminder notices phoned and scheduled video conferences set up. All automatically. The accounts receivable department needs a predictive dialer to dial all our deadbeats. The telemarketing department also needs a predictive dialer, but different programming.

  5. Desktop telephony. There are two important aspects. Call control and media processing services. Call control (also called call processing) is a fancy name for using your PC to get to all your phone system's features ” especially those you have difficulty getting to with the forgettable commands phone makers foist on us. *39 to transfer? Or it is *79. With attractive PC screens, you point and click to easy conferencing, transferring, listening to voice mail messages, forwarding, etc. There are enormous personal productivity benefits to running your office phone from your PC: You can dial by name, not by number you can't remember. You can set up conference calls by clicking on names and have your PC call the participants and call you only when they're all on the phone. You can transfer easily. You can work your voice mail more easily on screen, instead of having to remember "Dial 3 for rewind," "Dial 2 to save," and other obscure commands. Here's a wonderful quote from Marshall R. Goldberg, Developer Relations Group at Microsoft. He says "Voice mail systems that could benefit through integration with the personal computer largely remain isolated, difficult to use, and inflexible . Browsing, storing messages in hierarchical folders, and integration of address books ” functions just about everyone could use ” are either unavailable or unusable."

    The second benefit is media control. Media control is a fancy name for affecting the content of the call. You may wish to record the phone call you're on. You may wish to have all or part of your phone call clipped and sent to someone else ” as you often today with voice mail messages. You may wish to simply file your conversations away in appropriate folders. You may wish to be able to call your PC and get it to read you back any e- mails or faxes you received in the last day or so.

  6. Applying intelligence. A PC is programmable. The typical office phone isn't. A PC can be programmed to act as your personal secretary, handling different calls differently. It can be programmed to include commands, such as "If Joe calls, break into my conversation and tell me." "If Robert calls, send him to voice mail." etc.

  7. The Compound Document. The typed document lacks life. But add voice, image and video clips to it and it gets life. The LAN makes the compound document easier to achieve. The Compound Document gets attention.

  8. Management of phone networks. Today, phone networks are very difficult to manage. Often the PBX is managed separately from the voice mail, which is managed separately from the call accounting, etc. It's a rare day in any corporate life when the whole system is up to date, with extensions, bills and voice mail mailboxes reflecting the reality of what's actually happening. The latest generations of LAN software ” NetWare 4.1 and Windows NT ” have solid enterprise-wide directories and far easier management tools. Integrate these LAN management tools with telecommunications management, and potentially all you need is to make one entry (for a new employee, a change, etc.) and the whole system ” telecom and computing ” could update itself automatically, including even issue change orders to the MIS and telecom departments and vendors.

  9. No dedicated hardware in the PC. With only one link ” from the switch to the LAN ” there's no need to open the desktop PC and place specialized telephony hardware in each PC that wants to take advantage of the new LAN-based telephony features.

  10. Switch elimination . The ultimate potential advantage of LAN-based telephony is to eliminate the connection to the switch (PBX or ACD) by simply populating the LAN server (now called a telephony server) with specialized computer telephony cards and run the company's or department's phones off the telephony server directly.

Novell has effectively stopped marketing Telephony Services, but AT&T (now Lucent) continues to aggressively market it. and the benefits are still as valid as Novell detailed above. See Telephony Server NLM and Telephony Services Development Tools.

Telephony Workgroup

A concept that says work is done in groups and those groups need special telephony features and services. This is in contrast to most telephone installations today, where one giant phone system serves the company. Everyone shares the same automated attendant, the same voice mail, the same ubiquitous, universal, generic telephone features. But the concept of a telephony is that they shouldn't. Each group has different telephony needs: The sellers need phones that grab the caller's phone number, do a look-up on what the customer last bought and quickly route the call to the appropriate (or available) salesperson. The one who sold the customer last time.

The company's help desk needs a front end voice response system that asks for the customer's equipment serial number, some indication of the problem and tries to solve the problem by instantly sending a fax or encouraging the caller to punch his way to one of many canned solutions. "The 10 biggest problems our customers have." When all else fails, the caller can be transferred to a live human, expert at diagnosing and solving his pressing problem.

A development group might need e-mails and faxes of meeting agendas sent, meeting reminder notices phoned and scheduled video conferences set up. All automatically.

Computer telephony on a LAN can do to the workgroup what products like e-mail and Lotus Notes are doing ” substantially improve productivity (or at least, the pleasure of work). Except that the telephone is still less intimidating.

There are probably as many specialized telephony workgroups features needed as there are computer workgroup features needed. And since computer workgroup features are often provided on a local area network, it makes sense to provide many telephony features for that workgroup on the same local area network.


Harry Nyquist of Bell Telephone Laboratories began work in 1918 on a method of transmitting photographs over analog telephone circuits. In 1924, the effort culminated in telephotography, a term used to describe AT&T's photographic facsimile machine. A transparency of the photograph was mounted on a spinning drum and was scanned by the transmitting machine. The machine then modulated the amplitude of electrical signals across the analog PSTN in order to represent variations in the shades and tones of the transparency. The receiving machine demodulated the signal and deposited the results onto a sheet of photographic negative film mounted on a spinning drum. The negative was developed in a darkroom to create a facsimile of the original. Many of those principles are still used in contemporary fax machines. See also Facsimile Equipment and Nyquist, Harry.


The British name for the new generation of cheap, digital mobile phones. They're also called CT2. Think of telepoint phones as cellular phones but using micro-cells. By having smaller cells than normal cellular cells, CT2 phones can be smaller, cheaper and lighter. The first generation of these phones didn't do well, since they weren't smaller and lighter; there weren't many micro- cells and you couldn't receive an incoming call. See CT1, CT2 and CT2+.


The definition written by Gary Stix in the August 12, 1986 issue of Computer Decisions reads, "High bandwidth telecommunications distribution systems that allow major local users to obtain local, private services and long distance services. The most notable example is the New York Teleport," which is located on Staten Island. Teleports traditionally consist of two things ” a fiber optic /coaxial cable network around a city and a collection of nearby satellite antennas. The cable network collects transmissions from larger customers and takes them to the antennas for shipping to and from distant offices. Teleport companies are now more successful as local communications companies than they are as long distance gateways. Which is understandable, since the cost of local calls has gone up, while the cost of long distance calls has gone down.


In 1985 a team of researchers at NASA invented the notion of telepresence ” projecting yourself into someone else's virtual reality. In one version of telepresence, according to Discover Magazine, a computer prompts a robot to mimic your movements. As you manipulate objects in your virtual world a robot somewhere else does the same thing to real objects. Telepresence will be especially useful for hazardous jobs like repairing a nuclear reactor or satellite. Or going on a blind date? See Virtual Reality.


A teletypewriter. Also called a telex machine.


  1. Remote access data processing.

  2. Use of data link communications to accomplish a computer-based task; distinguished from Distributed Data Processing in that an application processor is not required at each and every node as in DDP.


British. Sales activities conducted by telephone in a planned and controlled manner.


  1. A generic term for services offered on phone links. Includes e-mail and facsimile features.

  2. A product of SunSoft, a division of Sun MicroSystems, Mountain View, CA. According to SunSoft, "Sun's vision of the impact of widespread use of teleservices suggests that the computer workstation will become the new communications center, combining many existing communication media with new ones, while creating new paradigms for the expression and sharing of ideas. Information in the form of charts and pictures, schedules and plans, and audio and video will merge through application programs that provide a collaborative vehicle for decisions in the 1990s and beyond. The desktop will become the platform for a new set of productivity tools, seamlessly integrated into the critical business activities and methodology of today's companies, and providing a competitive edge for facing the global challenges of tomorrow. Individuals will gain new freedom in where they work and how they access information. And ideas will be communicated in more expedient and creative ways." SunSoft has developed Solaris Teleservices to provide a platform for next -generation workstation applications which leverage the benefits and capabilities of the telephone network and the commonplace use of it. Teleservices applications, according to SunSoft, include:

Desktop Teleservices. Workstation based telephone and answering machine applications allow users to efficiently plant, receive and manage telephone calls.

Remote Access. Users can place calls for their workstation from any telephone and access applications and data through DTMF signaling, or perhaps through speech, using a workstation's speech recognition capabilities.

Wide Area Networking. The ubiquity of telephone networks allow for the complete connectivity of all computers. Network links can be brought up or taken down on demand merely by placing or tearing down a telephone call.

The Solaris Teleservices Platform is called XTEL, which is a multilayered software architecture based on client server computing model. XTEL consists of four key components:

A client side library. Providing a high-level, object oriented application programming interface (API) to application programmers. Using the XTEL API, an application can place and retrieve telephone calls. The API library consists of a collection of C++ objects which is linked to applications that wish to use the systems teleservices resources.

A server. Providing multi-client and multi-device support, the server is the central point of contact for all teleservices, resource management and security are provided by the server. Communication between the XTEL API and the server occurs through the XTEL Server Protocol (XTELS).

One or more providers. Manages each telecommunication device connected to the system. The Teleservices server communicates with an XTEL provider using the XTEL provider protocol (XTELP).

A data stream multiplexor (Sun's spelling). The universal multiplexor (Umux) provides a uniform means for applications to access and share data channels associated with a telephone call. Umux is a streams pseudo-device driver used to connect data channels to applications. An XTEL application is linked with the XTEL API library, through which communicates with the server using the XTELS protocol. XTELS is a synchronous, symmetric messaging protocol using the Solaris loopback transport mechanism. The XTELS protocol is essentially the XTEL provider protocol with extensions to support multiple clients and multiple XTEL providers. For more information, see a document called Solaris Teleservices Architectural Overview, available from SunSoft, Mountain View, CA. See Teleservices API.

Teletel Terminal Emulation

Teletel is a popular character-based graphics emulation for communicating with the Minitel service, found primarily in France.


An ITU-T standard for text and message transmission which is replacing Telex. Teletex operates at 2400 baud, about 50 times faster than telex. Teletex uses ASCII to encode its characters for transmission.


A data communications information service used to transmit information from remote data banks to viewers . It was transmitted over the air in the vertical blanking interval of the TV signal of the BBS (British Broadcasting Service). Teletext was originally designed for public consumption. It gave out weather information, sports results, headlines, etc. Teletext is proving somewhat more successful among corporations for the internal dissemination of information.

Teletraffic Optimizer Program

Derives data by processing actual calls instead of using an analytical model based on estimates or summaries.


Education and training through telecommunications.


A specific type of teletypewriter.

Teletyper Input Method

Teletyper Input Method (TIM) is specially designed for using pushbutton phone or mobile phone to input text, command and instruct your PC through the public telephone network. Teletyper Telephone-Input Method (TIM) and Teletyper Plus use three base keys on the phone pad with the combination of other keys to form alphabets, symbols, utility and control functions in order to command your PC remotely. Information could then be sent to fax, pager or voice output.

Teletyper Input Method (TIM)

01 =


*5 =


#8 = X

#1 =


05 =


*9 = Y

*2 =


#5 =


09 = Z

02 =


*6 =


#9 = space

#2 =


06 =


** = Enter

*3 =


#6 =


00 = Zero

03 =


*7 =


## = Backspace

#3 =


07 =



*4 =


#7 =


1 to 9 press 1 to 9

04 =


*8 =




TTY, as in TeleTYpewriter. A telegraph device capable of transmitting and receiving alphanumeric information over communications channels. It may also contain a keyboard similar to that of a typewriter or computer but usually with fewer keys. See Teletype.

Teletypewriter Control Unit

TCU. A device that serves as the control and coordination unit between teletypewriter devices and a message switching center when controlling teletypewriter operations.

Teletypewriter Exchange Service

TWX. A switched teletypewriter service in which suitably arranged teletypewriter stations are provided with lines to a central office for access to other such stations . TWX and Telex are commercial teletypewriter exchange services. They are currently both owned by AT&T. These days their revenues are in decline. A computer with a modem is a lot faster than TWX or telex.

Teletypewriter Signal Distortion

The shifting of signal-pulse transitions from their proper positions relative to the beginning of the start pulse. The magnitude of the distortion is expressed in percent of a perfect unit pulse length.


  1. TV. Translated from Greek and Latin, "far-off sight," television traditionally is thought of as broadcast TV, transmitted over the airwaves using radio broadcast frequencies. Most of us today think of TV as being provided by a CATV (Community Access TV) provider via coaxial cable. Increasingly, as many as 5 million U.S. viewers think of TV as being delivered directly via satellite. A standard analog TV channel today fits into a frequency bandwidth of 6 MHz.

  2. "Chewing gum for the eyes." Frank Lloyd Wright

  3. "Why should people go out and pay money to see bad movies when they can stay at home and see bad television for nothing?" Samuel Goldwyn, film producer.


The combination of computer and telecommunications technology which enables office workers to work at home or away from the main office on a part-time or full- time basis. See also Telecommuting.


A person who works from his home or some place distant from his company's office. A teleworker may send his completed work in and pick his new work up via a modem in his PC. A teleworker may also be on the phone at home answering calls on behalf of his company and entering the results of those calls (i.e. reservations on airlines, orders for catalogs) in on a PC connected by phone lines to his company. He may use one phone line, like an ISDN BRI line or he may simply use two analog phone lines ” one for talking on and one for PC's data. Or he may simply use one analog phone line and use a protocol such as VoiceView.


A worldwide switched message service. Telex service is offered in the United States by the Western Union Telegraph Company, MCI, ITT, RCA, FTCC and TRT. Telex has one gigantic advantage: Overseas it's very popular and widely used. Contacting overseas businesses by telex is often far more reliable and faster than contacting them by telephone. Telex is good for overseas time zone differences because you can send a message to an unattended telex machine. It also delivers a printed record. Telex is relatively inexpensive usually costing a little less than a phone call. Telex has one disadvantage : It's very slow and not very accurate with virtually no data communications error checking procedures. Telex is being rapidly displaced by faster, more accurate forms of data communications, including the public packet switched networks and the various electronic mail services, and most recently by massive competition from low-cost facsimile machines. See Teletex.

Telex Access Unit

TLXAU. An X.400 AU (Access Unit) serving Telex users.


A program that lets you connect to other computers on the Internet. The process by which a person using one computer can sign on to a computer in another city, state or country. Telnet is the terminal-remote host protocol developed for ARPAnet. Using Telnet, you can work from your PC as if it were a terminal attached to another machine by a hardwired line. The format of the telenet command is telnet address.domain or telnet address.domain port #. These days, most users are insulated from TELNET by GUI browsers, such as Netscape or Internet Explorer.

Telnet Port

The port address on a computer which supports remote telnet access. Normally port 23 is the default telnet port.

Telocator Alphanumeric Protocol

See TAP.

Telocator Message Entry

See TME.


A discontinued AT&T service that gave large customers discounts on purchases of multiple analog private lines. Telpak was to discourage users from building their own private microwave systems. Users who bought Telpak, however, were not allowed to resell any of the circuits, though they were allowed to share them. The FCC ruled Telpak as being discriminatory against competition. (It was too cheap.) It may still exist on an intrastate basis in some states. Telpak typically came in bundles of 12, 24, 60 and 240 voice lines. The bigger the bundle, the cheaper the per circuit cost.


Talker Echo Loudness Rating. A score, in dB (decibels), based on ratings by test subjects of the audibility of an echo in a communications channel. Echo in telecom channels is distracting, annoying and the reason satellites aren't used much for voice any longer. The most common source of echo is at two-wire to four-wire hybrids, such as at the line card of a digital switch. Echo can also be caused by poor handset design (receiver to transmitter coupling) or from speaker phones (speaker to microphone coupling). It turns out that the objectionability (new, invented word) of an echo is a function of the delay between when a speaker utters a word and the reception of the echo back at his/her handset, as well as the level (i.e. the volume). Delay can be introduced at a number of places. The long distance network is the most significant source. An intracontinental call will have a delay less than 30 msec, whereas intercontinental calls may have as much as 100 msec. Satellite calls have nearly 600 msec. Delay can also be introduced by digital customer premise equipment, as well as small delays due to encoding and switching in the local central office switches. VOIP (Voice over IP) networks tend to introduce significantly more delay than circuit switched networks. Therefore the need for echo cancellers is also greater with VOIP. Considerable reasearch has been done on this topic using test subject ratings. Both the level of echo and the delay affect the objectionability of an echo. The ITU-T standard G.131 discusses this relationship as "Talker Echo Loudness Rating". It demonstrates , for example, that delays of 300 msec must be suppressed by 40 dB more than an equally loud echo with a delay 5 msec to achieve the same relative level of annoyance. TELR, along with MOS (Mean Opinion Score), are two important factors that determine the subjective "quality" of a communications channel. The actual Talker Echo Loudness Rating is a score, in dB (decibels), based on ratings by test subjects of the audibility of an echo in a communications channel. Usually used in the context of comparing the relative audibility of a fixed echo as delay is varied. TELR is one of the factors involved in determining the MOS (mean opinion score). That makes it a hot topic. Delay is almost unavoidable in large-scale VOIP networks, and that delay makes TELR important. Contributed by Rolf Taylor, Applications Engineer, Telos Systems. See also: Echo, Echo Canceller, Echo Suppressor, Hybrid and MOS.


Total Element Long Run Incremental Cost. There are two problems in the regulated monopoly phone industry today. First, how to price end-user services like local phone service and second, how to price services ” such as the rental of local cable to companies such as CLECs ” competitive local exchange exchance carriers . In pricing such services ” and I instance only two examples ” there are three questions: First, what's the real cost? (There's obviously no way of figuring it.) Second, what do we want the answer to be? Third, what do you want the answer to be for political reasons? You may want the price to be low ” for example to help poor people in rural areas? In the phone industry there are as many ways of calculating prices as there are prices. Telric is a way of figuring out what phone service should cost based on the incremental cost of new equipment and new labor, not counting the embedded cost of old equipment and the labor to install that old equipment. Telric has been used to put a price cap on what telephone companies can charge for links to homes and businesses. Telric pricing is, according to George Gilder, "the Telric cap is based on an estimate of costs that would apply in a fully competitive environment, when bandwidth is a pure commodity." This is not exactly accurate, but then neither is Telric.


Telephone Set.

Telstar 1

Telstar 1 was the world's first active communications satellite. It was launched on July 10, 1962. (Sputnik was launched on October 4, 1957.) There is some argument about Telstar's claim to fame as the first. The engineers at the RCA Astro- Electronics Division, Princeton NJ (now Martin-Marietta Aerospace) claimed that they launched and successfully used a satellite to broadcast the coronation of the pope a little earlier than Telstar. But it was Telstar that got all the fame and glory , and that RCA engineers don't deny that.


Telstra is Australia's largest local and overseas phone company. The company has its origins in 1901, when the Postmaster-General's Department (PMG) was formed to manage all domestic telephone, telegraph and postal services. The Overseas Telecommunications Commission (OTC) was formed in 1946 to manage international telecommunications. The Australian Telecommunications Commission, trading as Telecom Australia, was created as a separate entity in July 1975, following the breakup of the PMG. Telecom Australia and OTC merged in February 1992 to form Telstra. On July 1, 1997, Australia's telecommunications markets were opened to full competition, with no limit on the number of carriers that own transmission infrastructure who can enter the market.

Temperature Rating

The maximum temperature at which the insulating material may be used in continuous operation without loss of its basic properties.


Unclassified name referring to the investigation, study, and control of compromising emanations from electrical and electronic equipment. Devices which are tempest- secure mean they do not send emanate electromagnetic signals which can, potentially, be received by others, i.e. enemies.


  1. A voice processing term. A pattern of information as a function of time, which is intended to represent an entire word.

  2. A Norstar definition: A system wide setting assigned during System Startup. The most important effects of a template are the number of lines assigned to the telephones, and the assignment of Line Pool Access. Templates will also assign other system wide defaults, such as Prime Line and Ringing Line assignment. It is important to understand that a template is only provided as a convenience, and that any settings effected by the template can be changed.

Temporal Coding

Compression that is achieved by comparing frames of video over time to eliminate redundancies between frames .

Temporary Signaling Connections

On August 14, 1995, AT&T announced Temporary Signaling Connections, which it billed as the first service that lets banks, retail outlets and other data- intensive businesses link their Software Defined Network locations together on demand using virtual connections created in AT&T's national signaling networks. Businesses can use Temporary Signaling Connections to verify credit card transactions, update inventory databases, exchange data with automatic cash machines. The service uses a portion of the D channel capacity of an ISDN PRI channel and passes information to other ISDN PRI locations.

Temporary Station Disconnection

Allows the attendant to completely remove selected phones from service at any time on a temporary basis.


I generally avoid temptation unless I can't resist it ” Mae West.


Transformer Exciting Network. A specially designed drainage reactor that provides a low impedance path -to-ground for longitudinally induced currents to flow. It bridges across one of the working circuits in an INT to serve as its "exciting" pair, thus freeing up a circuit that would have otherwise had to be grounded and unavailable for revenue-producing services. See INT.

Ten-High Day

A traffic engineering term for a traffic study which considers the average of the traffic during the same clock hour on the ten busiest normally recurring days of the busy season of the year. See Ten-High Day Busy Hour and Traffic Engineering.

Ten-High Day Busy Hour

A telephone company term. The hour, not necessarily a clock hour, which produces the highest average load for the ten highest business day loads in that hour. It may be a different hour from the ABS busy hour. With present data collection procedures, the ten high days are usually selected from the busy period.

Ten-High Day Data

THD. Data collected during the ten-high day busy hour. See above.

Tenant Partitioning

Also known a Service Bureau Capability. One computer or telephone host can provide service to many tenants in the building.

Tenant Service

Some businesses acquire a telephone system too large for their needs so they sell parts of the service to smaller offices in their own building or in the surrounding community. There are two ways to make money on tenant service ” renting phone equipment or re-selling long distance lines. There's more money on re-selling long distance lines.

Tensile Load

Refers to the maximum load or pull force that may exerted upon a cable during installation or relocation without damage. An excessive tensile load on twisted pair cables can cause elongation or untwisting which may result in signal loss.

Tensile Strength

A term denoting the greatest longitudinal tensile stress a substance can bear without tearing apart or rupturing.


See Telephone Equipment Order.


Pronounced "terr." From French or Latin meaning "third," or for the third time. Used in ITU terminology to indicate the third enhancement to an existing communications standard. For example, "V.27 ter" is the third enhancement to V.27 (or a subsequent enhancement to V.27 bis").


T. A million million, or a thousand giga-. A prefix that denotes 10 raised to the 12th power, or one trillion. In computer terms, however, tera- is actually equal to 2 raised to the 40th power power , or 1,099,511,627,776, the power of 2 that is closest to one trillion. See Terabyte.


A terabit is literally equal to 2 raised to the 40the power, 1,099,511,627,776 bits, but is often calculated with a base of 10 (10 raised to the 12th power), making it equal to one trillion bits. In short, one million million bits. The capacity of optical fiber is now moving into the terabit per second range. In April 1999, NEC announced it had achieved three terabits per second on a single strand of cable. That's 3,000,000,000,000 bits per second ” more than enough capacity to carry the entire Internet in the entire world. That brings some urgency not to break the cable.


A combination of the Greek "tera," meaning "monster," and the English "bite," meaning "a small amount of food." A unit of measurement for physical data storage on some form of storage device-hard disk, optical disk, RAM memory etc. and equal to two raised to the 40th power, e.g. 1,099,511,627,776 bytes . Roughly a trillion bytes. Here is the progression.

KB = Kilobyte (2 to the 10th power)

MB = Megabyte (2 to the 20th power)

GB = Gigabyte (2 to the 30th power)

TB = Terabyte (2 to the 40th power)

PB = Petabyte (2 to the 50th power)

EB = Exabyte (2 to the 60th power)

ZB = Zettabyte (2 to the 70th power)

YB = Yottabyte (2 to the 80th power)

One googolbyte equals 2 to the 100th power.

To put things in perspective ( courtesy of Microsoft), a terabyte holds a 100-byte record for every person on earth, as well as an index of those records; or a JPEG-compressed pixel for every square meter of land on earth, which is plenty to create a high-resolution photograph; or 1 billion business letters , which would fill 150 miles of bookshelf space; or 10 million JPEG images, which would provide 10 days and nights of continuous video.


A trillion (10 to the 12th power) floating point instructions per second. A measure of a computer's speed. A teraflop is a trillion calculations per per second. That one million million calculations per second.


THz. A unit denoting one trillion (10 to the 12th) hertz. See TERA-


A point of presence (POP) with a capacity of terabits per second. See Point of Presence.


Trans-European Research ann Education Networking Association. Formed in 1994 by a merger of Rare and Earn.

Term Sheet

A term sheet is a fancy name a piece of paper which lists the terms of an deal which everyone has agreed to. A term sheet is not the final legal agreement. It's the paper which everyone initializes as correct and then hands to the lawyers and tells them to "paper" it, in other words create a legally binding agreement which the parties will then sign later.


  1. The point at which a telephone line ends, or is connected to other circuits of a network.

  2. An input/output device for communicating with computers. Typically has a keyboard and a CRT (TV screen) display. See Terminals.

Terminal Adapter

TA. A Terminal Adapter, also known as an ISDN Modem, is an interface device that essentially is a protocol converter that serves to interface non-ISDN devices (e.g., PCs, fax machines and telephone sets) to an ISDN BRI (Basic Rate Interface) circuit. In more technical terms, a TA is an interface device employed at the "R" reference point in an ISDN environment that allows connection of a non-ISDN terminal at the physical layer to communicate with an ISDN network. Typically, this adapter will support standard RJ-11 telephone connection plugs for voice and fax, and RS-232C, V.35 and RS-449 interfaces for data. See also BRI and ISDN.

Terminal Address

Where there's a terminal to punch down, there's an address. That address will have numbers on it and will enable the technician who's responsible for fixing the circuit (when it breaks) to come, find it and fix it.

Terminal Block

A device used to connect one group of wires to another. Usually each wire can be connected to several other wires in a bus or common arrangement. A 66- type block is the most common type of connecting block. It was invented by Western Electric (now called Lucent). Nortel Networks has a terminal block called a Bix block. Other manufacturers make their own versions, though the Lucent one is most popular. A terminating block is also called a connecting block, a punchdown block, a quick-connect block, a cross-connect block. A connecting block will include insulation displacement connections (IDC). In other words, with a connecting block, you don't have to remove the plastic shielding from around your wire conductor before you "punch it down."

Terminal Configuration

The functional interconnection of the components of a terminal. For example, a keyboard-printer may be configured to transmit keystrokes without printing them. Printing is only performed on data retrieved from the communication line. Terminals with multiple components can be configured in a variety of ways.

Terminal Emulation

An application that allows an intelligent computing device such as a PC to mimic or emulate the operation of a dumb terminal for communications with a mainframe or minicomputer. It does this with special printed circuit boards inserted into its motherboard and/or special software. For example, TELECONNECT uses the communications software program called Crosstalk to emulate a DEC VT-100, a Digital Equipment Corporation VT-100 terminal. We do this because emulating a DEC VT-100 works better with certain software programs we call up remotely.

Terminal Equipment

Terminal Equipment usually refers to the telephones and other equipment at the end of telephone lines. See also CPE.

Terminal Equipment Type 1

TE1. In Integrated Services Digital Network (ISDN) technology, TE1 is a type of terminal compatible with ISDN.

Terminal Equipment Type

TE2. In Integrated Services Digital Network (ISDN) technology, a type of terminal that must be connected to ISDN via a specially designated point, normally an RS 232 or RS 449 interface.

Terminal Hunt Group

Also called Terminated Hunt Group. It's another name for a "top down" hunt group. You have a bunch of phone lines. They are in a "hunt" group which means that, if one is busy, the switch sends the call to the next available line in the hunt group. In a terminal hunt group, the switch always starts at the top of the hunt group and goes down, searching for the first available line from the top. This contrasts with a circular hunt group, where the switch remembers the last line it connected and, starting there, hunts down to the next available line, searching basically in a circle. A terminated or "top down" hunt group puts more calls on the first lines in the group. A circular hunt group tends to distribute the calls evenly. There are reasons why you might choose one type of hunt group over another. You might choose to evenly distribute your calls over a bunch of humans answering incoming calls or you might choose to send the calls top down to a voice mail system and watch the usage statistics carefully to tell if you need more or fewer lines and more or fewer voice cards.

Terminal Impedance

The impedance as measured at the unloaded output terminals of transmission equipment or a line that is otherwise in normal operating condition. The ratio of voltage to current at the output terminals of a device, including the connected load.

Terminal Interface Node

TIF. Provides the interface between a terminal and the Concert Packet Services network.

Terminal Node

In IBM Corp.'s Systems Network Architecture (SNA), a network device that cannot be programmed by the user.

Terminal Number

  1. A terminal number is one or multiple circuit numbers not identified by an individual directory telephone number (DTN) but by 001, 002, 003, etc. and is only referenced as a subset of the main trunk pilot DTN. Terminal numbers may be rented from both Incumbent Local Exchange Carriers (ILECs) or Competitive Local Exchange Carriers (CLECs), like MCI Worldcom. Terminal numbers are all organized to hunt (descending, ascending , most idle, least idle). A terminal number is another name for an auxiliary or private line that doesn't have a real number, doesn't get a listing in the phone book, but gets a monthly bill. An auxiliary number is a telephone trunk you rent from your local phone company in addition to the main number you rent. Phone systems are always set up for multiple phone lines, so that when a call comes in, it doesn't hit a "busy," but rolls over to one or more auxiliary lines. That collection of lines is called an Incoming Service Group, or ISG. For example, the publisher's main office main number is 212-691-8215. But it also has 8216, 8217, 8218 and several unmarked or coded trunks. All these numbers are auxiliary lines and don't receive their own bill or directory listing from the phone company. Costs for these lines are lumped onto the bill for the main number. See Rollover and ISG.

  2. TN. The physical address of a device (such as, telephone set, a truck, and attendant) on a Nortel Networks' PBX. The TN is composed of the loop, shelf, card and unit IDs.

Terminal Repeater

A repeater for use at the end of a trunk line.

Terminal Server

A small, specialized, networked computer that connects many terminals to a LAN (local area network) through one network connection. Any user on the network can then connect to various network hosts . A terminal server has a single network interface and several ports for terminal connections. One advantage of a terminal server is it allows many terminals to be connected to a host via a single existing LAN cable or hub, rather than a variety of point-to-point cables. A terminal server is especially valuable where lots of asynchronous terminals require low-speed access to a host computer. Since asynchronous devices output a character at a time, and since LANs work on the basis of a frame with minimum and maximum frame sizes, asynchronous terminal devices can be very wasteful of LAN resources ” the frames must be padded with stuff bits in order to satisfy the minimum frame size. The terminal server accepts individual characters output from the terminals and the ports to which they are connected, buffers them, interleaves them, packetizes them in LAN frames, and places them on the network through a process much like Time Division Multiplexing (TDM). At the target host computer, a matching terminal server recognizes the type of traffic by virtue of the port address of the incoming traffic, and breaks down the frames to get at the individual characters generating by the originating asynchronous terminals. See also Asynchronous, LAN, Server, and TDM.

Terminal Shelf

A terminal shelf is an area inside a FOTS (Fibre Optic Transmission System) which is used to house the circuit cards inside the bay.

Terminal Table

An ordered collection of information that identifies each line, phone, component or application program from which a message can be sent.


The screws or soldering lugs to which an external circuit can be connected.

Terminals To Long Distance Operator

Commonly known as "toll terminals", they provide special trunks directly to the long distance telephone company operators. Upon completion of long distance calls, the toll operator will ring the attendant (or hotel operator) and give them "time and charges" for the phone call just ended.


  1. To connect a wire conductor to something, typically a piece of equipment.

  2. To end one's telecommunications service or equipment rental.


  1. The condition of a wire or cable pair which is connected to (terminated on) binding posts or a terminal block.

  2. The condition of a circuit connected to a network which has the same impedance the circuit would have if it were infinitely long.

Terminated Line

A telephone circuit with a resistance at the far end equal to the characteristic impedance of the line, so no reflections or standing waves are present when a signal is entered at the near end. Compare with bridge tap.

Terminating Channel

The name for the circuit in a private line channel that connects a local central office with the CBX/PBX or telephone instrument at the customer's premises.

Terminating Multiplexer

TM. A type of Path Terminating Equipment (PTE) used to provide access to a SONET/SDH network. The Terminating Multiplexer is equivalent to a Time Division Multiplexer (TDM) in a T/E-Carrier context. The TM also serves to perform the signal conversion process from electrical to optical on the transmit side, reversing the process on the receiving end.

Terminating NPA/NXX

The area code and exchange of the number dialed.

Terminating Office

The switching center (i.e. the central office) of the person you're calling (the "called party").

Terminating Only Traffic

A type of circuit operation that provides for traffic in the terminating direction only (from the carrier to the end user).

Terminating Resistor

A grounding resistor placed at the end of a bus, line, or cable to prevent signals from being reflected or echoed . Sometimes shortened to terminator.


Termination involves the placement of impedance matching circuits on a bus to prevent signals from being reflected or echoed.

Termination Restriction

Prevents a user from receiving any calls on the phone line. A DID call to the restricted termination routes to an attendant, an announcement or intercept tone at customer option. All other calls route to intercept tone.

Termination Of Service

The end of service of a line or equipment. All pursuant to the regulations set forth in the tariff .


Some communications facilities ” e.g. local area networks ” are bus configurations. This means one long piece of cable with workstations connected along the way, typically with "T" connectors. For a network to work properly, you need to place resistance at the end of the cable that serves to absorb the signal on the line. A thin wire Ethernet typically requires a 50 ohm resistance at either end of the bus. You can buy these Ethernet terminators already included in a connector.


A device used to terminate an optical fiber that provides a means to locate and contain an optical fiber within a connector.


Long distance facilities which are entirely on land and do not use satellites. This includes microwave, coaxial cable, optical fiber, normal cable, etc. There are reasons to prefer terrestrial facilities over satellite facilities:

  1. No echo or delay in voice conversation. Some people find satellite conversations disturbing because of the delay; and

  2. No significant reduction in data throughput. Most data communications protocols send their data in " chunks " and require an acknowledgement from the other end when one chunk has been received before the next chunk can be sent. When it takes a long time for an acknowledgement to be received (as in a satellite circuit), the effective throughput of data becomes very slow.

When you're trying to send one one-way signal to many locations, satellites often do a better and cheaper job.

Terrestrial Interference

TI. Interference emanating from sources on the earth as distinguished from those emanating in space.

Tesla, Nikola

Nikola Tesla is regarded as one of the most mysterious and least recognized scientific pioneers in modern history. He is commonly associated with high-frequency electrical devices, radio transmission, and the invention of the multi-phase alternating current system in use today. Born on July 9, 1856 in Smiljan, Lika, Croatia, Yugoslavia, Tesla was the fourth of five children and son of a reverend of the Serbian Orthodox Church. Tesla was educated at the polytechnical school at Graz, Austria (1875), where he acquired an interest in the study of electrical engineering and mathematics. Tesla was dismayed at the inefficient design of DC motors. While working as a telegraph operator in Budapest (1881) and later as a telephone engineer for Edison in Paris (1882), he developed a multi-phase alternating current power system, named the Tesla Polyphase System. Other engineers had attempted AC designs modeled after direct current systems with a single circuit, but none were ever successful. Tesla's multi-circuit system included new polyphase induction motors, dynamos, and transformers , the patents to which were purchased in 1888 by the Westinghouse Electric Company from the Tesla Electric Company.

Tesla's 60 cycle AC Polyphase System was the primary competitor to the Continental Edison Company's DC Current System, and caused Thomas Edison to personally wage a massive propaganda campaign against Tesla and the "dangers of alternating current". However, AC could travel over hundreds of miles and at much higher voltages, while DC traveled only much shorter distances and required a generator every two miles. Despite Edison's efforts, the war of the currents was won by Tesla. The Chicago World's Fair in 1893 featured the first electrically powered pavilion, designed entirely by Tesla using his polyphase system and financed by Westinghouse. This pavilion featured Tesla demonstrating many high-energy devices, including the wireless transmission of energy using a tuned circuit, a device that would come to be known as radio. Guglielmo Marconi used several of Tesla's patents in his 1901 "invention" of the wireless radio transmitter. Marconi's initial patent claims for this device were rejected based on Tesla's prior patents (645,576 and 649,621 granted in 1900) for the wireless transmission of energy. Marconi's later patent claims for a signal communications device were granted. Despite a lawsuit filed by Tesla in 1915 and other efforts, history has erroneously painted Marconi as the inventor of the radio. Some redemption to this injustice occurred when the Supreme Court ruled on June 21, 1943 in the case of Marconi Wireless Telegraph Company of America vs. the United States that Tesla's radio patents predated those owned by Marconi. In effect, this ruling declared Tesla the inventor of radio; it came five months after his death.

Tesla continued to experiment with high-frequency energy. He believed that energy in phase with the natural vibrations of thunderstorms and the Earth (7.68 Hz) could be broadcast to anyplace. Using this theory, he received backing from J.P. Morgan to build a worldwide telegraphy system. Tesla also believed that electrical power was present everywhere, in unlimited quantities , and free for the taking. Tapping into such a natural source of energy could replace all other fuels. The global wireless transmission of power, however, did not interest Morgan, who did not see the benefit in providing free electricity to humanity. Tesla created hundreds of inventions and improvements during the course of his life, including the telephone repeater, wireless communications, radio, antennas, ground connections, aerial ground circuits with inductance and capacitance , tuned circuits, emitters and receivers tuned to resonance , the electronic tube, fluorescent lighting, the electromechanical audio speaker, AND and OR logic gates, radio remote-control , robotics , radar, and diathermy.

Tesla's patented inventions includes a robotic submarine (613,809), vertical take-off and landing aircraft (1,655,114), disk (bladeless) turbine engine (1,329,559), ozone generator (568,177), electro-dynamic induction lamp (514,170), and superconduction (685,012). His more fantastic concepts include anti-gravity propulsion and a thought photography machine. The more than 700 patents Tesla was awarded during his lifetime represent only a fraction of his total number of inventions and discoveries. Tesla often didn't bother to patent many of his inventions (he received his last patent in 1928) and often failed to document his work. Tesla died on January 7, 1943 secluded in his New York City apartment at the age of 86. Tesla was intelligent, highly strung, neurotic, charismatic, germ-phobic, and always very well-dressed. Over his lifetime his financial backers were a diverse group including George Westinghouse, J.P. Morgan, and even Thomas Edison. His friends and supporters, an equally diverse group, included Albert Einstein, Samuel Clemens, and Eleanor Roosevelt. His manor and mystery as depicted by the press inspired the creation of evil comic book geniuses that did battle with Superman and Captain Marvel using a myriad of strange inventions and energy devices. Tesla's secret work on "death ray" energy devices fueled much of this, as did the U.S. government's confiscation of many of his inventions after his death.

Test And Validation

Physical measurements taken to verify conclusions obtained from mathematical modeling and analysis.

Test Antenna

An antenna of known performance characteristics used in determining transmission characteristics of equipment and associated propagation paths.

Test Bed

A constant physical and electrical environment in which devices or programs are tested in order to measure their performance against requirements, benchmarks, or each other.

Test Board

A switchboard equipped with testing apparatus.

Test Center

Equipment for detecting and diagnosing faults and problems with communications lines and the equipment attached to them. If centralized, a facility where a network manager or technician can gain access to (almost) any circuit in a network for the purpose of running diagnostic testing. Also called a network control center.

Test Desk

A desk equipped with equipment to test and repair subscriber lines. See also Test Center.

Test Friendly Busy

A test to see if a line is busy. The subscriber does not know the line is being tested. Such a test is usually performed by the operator if someone calling that number requests it. It used to be free. So did a lot of things in this world.

Test Intrusive

Breaking a circuit in order to test its functionality. Testing intrusively will drop service on the circuit.

Test Repeatability

This definition courtesy Steve Gladstone, author, "Testing Computer Telephony Systems," (available from 212-691-8215) says that a key component in any successful test program is the ability to repeat tests simply and quickly. If problems are found, tests must be rerun, both to help recreate and document the problem, as well as to verify the bug fix. Repeating tests can be very time consuming as many tests will change the state of either the test system or the computer telephony system under test. For example, checking that messages are correctly deleted means starting the test from a known state where messages are in a mailbox. When the test is completed usually there are fewer messages left than when the test started. Repeating the test may therefore necessitates reinitializing the computer telephony system to the state before the test started.

Test Set

A telephone handset with extra electronics designed to test telephone circuits. Also called a butt set, since it typically hangs on the technician's tool belt near the wear- er's butt... Well, that's one explanation. Another is that it's called a "butt" set because it allows the use to "butt in" to a conversation and listen to its quality, etc.

Test Shoe

A device that is applied to a circuit at a distributing frame to gain test access to circuit conductors.

Test Tone

A tone used to find trouble on phone lines. Also called installer's tone. A small box that runs on batteries and puts an RF tone on a pair of wires. If the technician can't find a pair of wires by color or binding post, they attach a tone at one end and use an inductive amplifier (also called a banana or probe) at the other end to find a beeping tone. A more technical explanation: A tone sent at a predetermined level and frequency through a transmission system to facilitate measurement and/or alignment of the gains and/or losses of devices in the transmission circuit.

Test, Friendly Busy

A test to see if a line is busy. The subscriber does not know the line is being tested. Such a test is usually performed if someone calling that number requests it.


The ability of a system to support testing and verification of the services it offers.


An all-encompassing term including the concepts of wireless mobility and intelligent network services (such as the ability of a user to roam freely among wired and wireless networks while making and receiving calls.


Terrestrial Trunked Radio. An European Telecommunications Standards Institute (ETSI) standard for the type of mobile radio known variously in the US as TMR (Trunk Mobile Radio) and SMR (Specialized Mobile Radio). The typical application for such systems is in local communications with fleets of vehicles, such as taxicabs, fire trucks , police cruisers, and emergency vehicles. TETRA divides these applications into PAMR (Public Access Mobile Radio) and PMR (Private Mobile Radio). PAMR includes applications such as fleets of taxicabs, delivery vehicles, and utility vehicles. PMR applications include fleets of public service and emergency vehicles. TETRA combines the features of mobile cellular telephony, fast data communications and the workgroup capabilities of mobile radio. A measure of the reliability and range of functions of the TETRA standard is that it has already been adopted by many public safety and emergency organizations. The technology behind TETRA creates new standards of network service and functionality at a cost- effective price. It gives you "press-to-talk" instant call set-up for individual and group calls as well as the expected added-value features found in any advanced mobile network. TETRA operates on a simplex (one-way communications) basis, making use of TDMA (Time Division Multiple Access) for digital communications over 25 kHz channels in the 400 MHz frequency band. the 400 MHz frequency band supports good signal propagation over relatively long distances, compared with the GSM band of 900 MHz. TETRA's packet data transfer operates at up to 28.8 Kbps through the concatenation of four digital time slots. This, together with the Short Data Service (text and numeric messaging), provides the fastest and a flexible mobile data transfer capability available. SDS allows the transmission of four different message types, with Type 4 supporting data transfers up to 2047 bits, which is approximately 256 bytes (i.e., characters). Advanced TETRA technology delivers great voice quality which is especially impressive in noisy industrial environments and in-car, hands-free operation. TETRA operates in both the "open channel" mode and the Direct Mode. The open channel allows all terminals to hear all communications, which are handled through a centralized dispatcher. The Direct Mode is a "walkie-talkie" mode that allows direct operation between terminals. The TETRA Memorandum of Understanding (MoU) was established in December 1994 to create a forum which could act on behalf of all interested parties, representing users, manufacturers, operators, test houses and telecom agencies. Today the TETRA MoU represents 58 organizations, from 19 countries . See also APCO25, SMR, SMS.


A four-element vacuum tube, consisting of filament (or cathode ), grid, screen grid and plate.


Transmitted characters which make up the body of a message.

Text Based Browser

A browser that cannot handle hypermedia files.

Text Enriched

The successor to MS-DOS text/richtext, is a simple text markup language for MIME that lets you mark up the document (using commands enclosed in angle brackets) without making the text unreadable to someone without the software to interpret it. See MIME.

Text File

A file containing only letters, numbers, and symbols. A text file contains no formatting information (like bolding and underlining and type fonts and sizes), except possibly line feeds and carriage returns. A text file is an ASCII file. A text file can be read by every word processor and editor. A text file the lowest common denominator in the word processing world. I wrote this file with an editor called The Semware Editor, which produces only text files. I did this because this dictionary has to be sent to a Macintosh for "type- setting" and to a DEC for distribution on CD-ROM. And a text file is the form both easily recognize.

Text Messaging

Text messaging is a simple term for what it is ” sending messages (also called email) in plain text to various devices ” wired or wireless. The most common implementation of text messaging is something called short message service ” SMS or S.M.S. It is a way by which short messages can be sent to and from digital cell phones, pagers and PDAs (personal data assistants) other handheld wireless devices. Alphanumeric messages of up to 160 characters can be supported by SMS. That's adequate for stock quotes, filtered (abbreviated) e-mail, bank account balances, buying movie tickets on line, updates on traffic conditions, answers to quizzes posed by the teacher and other really short messages. Europeans, who have relied on digital cell phones for years, prefer to send short text messages by tapping on their telephone dialing pads. SMS is defined in IS-41C. Text messaging is about to get a big boost from 2.5G ” second and a half generation digital wireless phones and systems and 3G ” third generation. These new generations will seriously expand the the amount of characters and the quality of images that can be sent back and forth to and from cell phones. See also IS-41 and Wireless Application Protocol (WAP).

Text Telephone

A machine that employs graphic communication in the transmission of coded signals through a wire or radio communication system. TT supersedes the term, "TDD" or "telecommunications device for the deaf."


TTS. Technologies for converting writtten text into spoken speech output. A system with text-to-speech (TTS) capabilities is able to interpret electronic text and generate audible speech from it. Text-to-speech technology can be used in many different ways including reading email, airline timetables, etc. TTS is used in computers from laptops to over the phone applications. It is used in interactive voice response (IVR) systems. IVRs provide information such as credit card balances, movie listings, etc., verbally to customers who access the system by phone. See also Drunken Swede, IVR and Speech Concatenation.


See Text Messaging.


Business PBX Trunk.


PBX Service, Combination Flat Rate Trunk.


Thin Film Transistor Liquid Crystal Display panels are currently the most widely used flat panel display technology. TFT-LCDs are used in notebook computers, desktop monitors , televisions , digital cameras , portable DVD players, mobile phones, portable games , and car navigation systems, among other applications. TFT-LCDs work by assigning a tiny transistor to each pixel, making it possible to control pixels independently of each other. TFT screens are very fast, have a high contrast ratio and a wide viewing area.


Trivial File Transfer Protocol. A simplified version of FTP that transfers files but does not provide password protection or user-directory capability. It is associated with the TCP/IP family of protocols. TFTP depends on the connectionless datagram delivery service, UDP.


Terrestrial Flight Telephone System.


  1. Trunk Group.

  2. Task Group. A term used by the IEEE (Institute of Electrical and Electronics Engineers) for a group of people who work on tasks associated with larger standards recommendations that are the overall responsibility of a Working Group (WG). See also 802.15.


  1. Trunk Group Busy

  2. Telecommunications Grounding Busbar. See TBB.


Transmission Group Control in IBM's SNA.


Terminator group - type E.


Terminator group - type F.


Trunk Group Warning.


Transmission Header, an SNA term.


Total Harmonic Distortion Plus Noise. A measure of the audio clarity of a voice system. The best measure is 0%., or close. Pretty bad is 25%. The average PC voice card is around 10%.

The Full Monty

To strip completely naked. There's a movie and a play of the same name.

The Grand Alliance

A consortium of seven organizations which produced a workable version of HDTV ” High Definition TV. The companies are AT&T, General Instrument Corporation, The Massachusetts Institute of Technology, the David Sarnoff Research Center, Philips Consumer Electronics, Thompson Consumer Electronics and the Zenith Corporation.

The Open Group

Formed in February 1996 through consolidation of the Open Software Foundation (OSF) and X/Open Company Ltd. (X/Open). The stated mission of The Open Group is to make multi-vendor open systems the preferred customer choice for the delivery of the right information to the right person at the right time. Specific goals include the following: 1) Enabling a rapid vendor response to customer requirements for open systems, 2) Innovative technology research, 3) Accelerated consensus-building around standards and technology, 4) Consensus among open systems vendors, and 5) Promoting a consistent open systems message. Examples of The Open Group's work include the X Window System specification, the Motif Toolkit API, the Distributed Computing Environment (DCE) and Network File System (NFS) specifications, and the Common Desktop Environment (CDE) specification. (

The Phone Company

Also known by the initials TPC. In the 1966 James Coburn movie "The President's Analyst", the evil worldwide conspiracy was run by TPC, which turned out to be The Phone Company. Some people believe the movie was not fiction .


In the fields of mathematics and logic, a theorem is a formula, proposition, or statement that is deduced from other formulas or propositions . In popular usage, a theorem is an idea that is accepted or proposed as a demonstrable truth that may be part of a broader general theory. See also Nyquist Theorem and Shannon's Law.

Theoretical Midpoint

TMP. The theoretical halfway point that divides an international private line circuit into its respective US and foreign halves . A US records carrier is responsible for the US portion of service and a foreign records carrier assumes responsibility for service to the foreign half.

Thermal Ducting

The phenomenon that occurs when the difference in temperature from day to night increases , specifically in the Fall, that causes radio signals (cellular) to travel further than should be possible. An example would be when a handheld cellular user is in central Nebraska, but is using a cellular tower signal in Kansas.

Thermal Management

A fancy term for cooling.

Thermal Noise

Noise created in an electronic circuit by movement and collision of electrons.

Thermionic Emission

The emission of electrons or ions under the influence of heat, as in a vacuum tube cathode.


A resistor whose resistance varies with temperature. More technically, a thermistor is a device made from mixtures of metal oxides that exhibits large negative coefficient of resistance changes as the temperature increases.


Two dissimilar wires joined together that generate a voltage proportional to temperature when their junction is heated.


Material that will soften and distort from its formed shape when heated above a critical temperature peculiar to the material.


A plastic material which is crosslinked by a heating process known as curing. Once cured, thermosets cannot be reshaped.


Thermostats are temperature-activated on/off switches that usually work on the 'bimetal' principle, in which the bimetal strip consists of two bonded layers of conductive metal with different coefficients of thermal expansion, thus causing the strip to bend in proportion to temperature and to make (or break) physical and electrical contact with a fixed switch contact at a specific temperature. In practice, the bimetal element may be in strip, coiled, or snap-action conical disco form, depending on the application, and the thermal 'trip' point may or may not be adjustable. Figures 8(b) and (c) show the symbols used to represent fixed and variable thermostats. A variety of thermostats are readily available, and can easily be used in automatic temperature control or danger-warning (fire or frost ) application. Their main disadvantage is that they suffer from hysteresis; typically, a good quality adjusted thermostat may close when the temperature rises to (say) 21 C, but not re-open again until it falls to 19.5 C.


Tremendously High Frequency.


Telephone Headset Integrator. A new form of headset manufacturer who will make headsets that do new tasks, like take a phone off hook without physically having to lift the receiver off the phone.

Thick Ethernet Cable

Thick Ethernet cable is 0.4-inch diameter, 50-ohm coaxial cable. Thick Ethernet cable can be bought in pre-cut lengths, with standard N-Series male connectors installed on each end. It also is available in bulk cable without connectors. Any of the following types of connectors will work:

Belden 9880 or Belden 89889 Montrose CBL5688 or Montrose CBL5713 Malco 250- 4315-0004 or Malco 250-4314-0003 Inmac 1784 or Inmac 1785


Jargon used to describe thick Ethernet coaxial cable. See Thickwire.


0.4 inch diameter, 50-ohm, Ethernet IEEE 802.3 coaxial cable. See also Thick Ethernet Cable and Thinwire.

Thin Client

Here's Citrix's definition: A low-cost computing device that works in a server-centric computing model. Thin clients typically do not require state-of-the-art, powerful processors and large amounts of RAM and ROM because they accesses applications from a central server or network. Thin clients can operate in an application server environment.

Here's my longer definition: Clients are devices and software that request information ” applications or files. A client is a fancy name for a PC or workstation which is connected to a network, such as a local area network (LAN), a company's Intranet or, the Internet. The client runs on a server which houses applications and/or files. Clients come in two varieties ” Fat and Thin. A "thin client" is a relatively cheap workstation akin to a dumb terminal in a mainframe environment. The thin client, according to current definition, lacks a hard drive, modem, PCMCIA slot, CD-ROM drive, floppy drive, serial port, communications port. The thin client comprises a sealed unit with often no potential for enhancement, other than adding memory. However, it does contain RAM, a limited processing power and perhaps a burned-in chip with a program or two, perhaps its user interface. The bulk of the applications and the information it needs remain on the server. Hence, the thin client is totally dependent on the server. The advantage of a thin client is low TCO (Total Cost of Operation), including costs of acquisition, maintenance and support. The downside is that the thin client is totally reliant on the server, through the network. Should either the server or the network fail, the client effectively is rendered useless until the problem is resolved. Here's a definition of Thin Client, courtesy of Oracle Corporation, writing in early 1994: "The thin client modem stores and processes more data on the server, but keeps the user interface and application functions on the client device. Example: a television with a settop box, Apple's Newton Personal Digital Assistant, or a low-end PC."

In an Internet scenario, thin clients are known as NetPCs or Netstations. The NetPC is reliant on the server, which is provided by a service provider (e.g., America OnLine, CompuServe, or your ISP). In addition to providing some combination of content and Internet access, the service provider's server will provide your client NetPC with access to all necessary applications (e.g., word processing and spread sheet applications), will store all your personal files, will provide all significant processing power, and so on. In this Internet example, the NetPC differs from the standard thin client by virtue of the fact that it does contain a modem, a communications port and communications software, all of which are required for Internet access. See also Client, Client Server, Client Server Model, Fat Client, Mainframe Server and Media Server.

Thin Computing

See Thin Client.

Thin Ethernet

A coaxial (0.2-inch, RG58A/U 50-ohm) that uses a smaller diameter coaxial cable than standard thick Ethernet. Thin Ethernet is also called "Cheapernet" due to the lower cabling cost. Thin Ethernet systems tend to have transceivers on the network interface card, rather than in external boxes. PCs connect to the Thin Ethernet bus via a coaxial "T" connector. Thin Ethernet is now the most common Ethernet coaxial cable, though twisted pair is gaining. Thin Ethernet is also referred to as ThinNet, ThinWire or Cheapernet. See also 10BASE-T.

Thin-Film Interference Filter

Thin-film filters control the reflection, refraction, transmission, and absorption of light waves. Filters are used in a wide variety of optical components, and the majority of today's WDM systems incorporate thin-film filter technology for multiplexing and demultiplexing. Interference filters are constructed by depositing a series of coatings with different refractive indexes on a glass substrate. This construction generates interference patterns as lightwaves pass through such that certain wavelengths are reflected while others pass through undisturbed. In DWDM applications, at lower channel counts and larger spacing between wavelengths , thin-film filters are produced in volume quantities that can process channel spacings of 200 Ghz. However, at higher channel counts and smaller channel spacings (below 100 Ghz and 50 Ghz), manufacture becomes increasingly difficult. The value proposition for competing multiplex - ing/ demultiplexing technologies such as arrayed waveguides and fiber bragg gratings becomes increasingly compelling as channel count increases.


See Dingy.


Jargon used to describe thin Ethernet coaxial cable. Referred to ThinNet, ThinWire or Cheapernet.


The 50-ohm coaxial cable listed in IEEE 802.3 specifications and used in some Ethernet local area network installations.

Third Generation Wireless

See 3G.

Third Order Harmonics

The third multiple of a specific frequency or a specific frequency multiplied by three.

Third Party Call

Any call charged to a number other than that of the origination or destination party. It's not a good idea to let your employees make third party calls to one or more of your phone numbers. Best to ask them to place the calls on their personal phone credit cards. This way, they will spend a modicum of time justifying their exorbitant phone calls.

Third Party Call Control

A call comes into your desktop phone. You can transfer that call. When the phone call has left your desk, you can no longer control it. That is called First Party Call Control. If you were still able to control the call (and let's say, switch it elsewhere) that would be called Third Party Call Control. Some Computer Telephony links allow only first party call control. Some allow third party as well. If you control the switch ” the PBX or the ACD ” you will typically have Third Party Call Control. If you just control the desktop, you'll typically have only First Party Call Control. There is no such animal as Second Party Call Control.

Third Party Cookie

See Cookie.

Third Party Verification

TPV. Before your Primary Interexchange Carrier (PIC), or long distance carrier, can be changed, the FCC now (1988) requires that the new carrier have a in place a means of verifying that you have authorized such a change. Business customers must execute a written Letter of Agency (LOA), which the new carrier can present to the old carrier. The veracity of a change for residential customers is ensured through Third-Party Verification (TPV), which takes the following form. Once you have concluded your conversation with the sales representative of the new carrier, the sales rep will initiate a conference call to add to the call a representative of an independent third party. The third party will verify the change, including all relevant information recorded by the sales representative. This step protects you from "slamming," which is the practice of changing your PIC without your authorization. See also LOA, PIC, and Slamming.

Third Place

A video screen, particuarly the screen on a cell phone, that a person uses almost as often as their television and computer screens. Like Starbucks' relentless attempts to sell itself as the "third place," the wireless industry is trying to sell itself as the "third screen." The electronic notion of a "third screen" is based on the idea of a "third place," which is a place other than home or work where a person can go to relax and feel part of the community, e.g. Starbucks coffee shops .

Third Wire Tap

The activating of a telephone handset microphone by using a third wire, thus bypassing the hook switch.


Trans Hybrid Loss.

Thought Police

In Imperial Japan before World War II, members of the "thought police" ” Shisou Keisatsu ” spread out to suppress dangerous thinking in the populace. Such dangerous thinking was obviously different to what the imperial government wanted. The Thought Police were disbanded by General McArthur when he imposed freedom of speech after the War. The thought police was later chillingly immortalized by George Orwell in his 1949 "1984."

Thousand Block Number Pooling

See Number Pooling.


A computer has a finite amount of memory and processing capability. If a process or program or user makes a request that can't be met, the OS (Operating System) may borrow resources from another process in an attempt to satisfy the request. The process from which the resources were borrowed then borrows resources from another process. And so on, and so on. The computer thrashes about looking for resources, and never getting anywhere . You get either a blank screen or a frozen screen. Your computer has just crashed. Thrashing can be caused by a number of things, including your clicking around too fast, so just slow down and take things one at a time. See also Crash.


  1. A thread is a sequence of computing instructions that makes up a process or program. A program can be single-threaded or multi-threaded. A single-threaded application program insists that only a single instruction can be executed at a given time. All the instructions must be executed in an exact sequence, from beginning to end. For example, a single-threaded Internet experience might involve your accessing a Web-based server that would accept your request to establish a session, and would accept and serve your request for information. During this period of time, a tightly choreographed series of steps would take place in exact sequence, and no requests from other clients would be accepted until your request was satisfied. In other words, a single-threaded program must follow a single line of logic in a very rigid manner.

    A multi-threaded process has multiple threads, each executing independently and each perhaps executing on separate processors within one or multiple computers. A multi-threaded program has multiple points of execution (one per thread) and, therefore can perform multiple tasks associated with multiple processes and multiple programs supporting multiple users at any given time. As each task associated with each task associated with each process supporting each program and each user is completed, the thread for that task is resumed at the same point it had been interrupted , much as though it had been bookmarked. As multiple instruction sets can be executed concurrently, the throughput and speed of running the program is much improved. In other words, a multi-threaded program, if running on a computer with multiple processors, will run much faster than a single-threaded program running on a single processor machine.

  2. In the context of an Internet Usenet newsgroup or other interactive discussion forum, a thread essentially is a train of thought or line of logic that can be followed through the fabric of a larger subject. A thread begins with a message posting. Responses are "hung off" of that initial posting in a chronological and hierarchical fashion as comments are offered and elicit additional comments, and as questions are posed and answered and the answers elicit yet other sets of questions and answers. This hierarchical threading is very easy to follow in graphical format, such as that used in the World Wide Web. See also Hyperthreading, Threaded and Threaded Code.


A method of presenting articles within a newsgroup in a way that shows which articles refer to which other ones. See Thread.

Threaded Code

Threaded code is also known as Threaded Pseudo Code, or threaded p-code . It was first popularized in a software language called Forth. Eventually Microsoft fixed Forth and changed it into Basic. See Thread.

Threat Analysis

Examination of all actions and events that might adversely affect a system, a network or an operation.

Three Finger Salute

Ctrl Alt Delete.

Three Dog Night

Three Dog night, attributed to Australian Aborigines and the American Eskimos) came about because on especially cold nights these nomadic people needed three dogs (dingos, actually) to keep from freezing.

Three Nines

99.9%. Three nines typically refers to the reliability of a system (computer, telephone system, etc.) that works 99.9% of the time. These days the industry talks increasingly of five nines reliability, i.e. 99.999% and fo six times reliability, e.g. 99.9999%.

Three Slot

An obsolete pay phone that is identified by three separate coin slots.

Three- Tier

A type of client/server architecture consisting of three well-defined and separate processes, each running on a different platform:

  1. The user interface, which runs on the user's computer, also called the client.

  2. The functional modules that process the data. This middle tier runs on a server. It is often called the application server.

  3. A database management system (DBMS) that stores the data required by the middle tier. This tier runs on a second server called the database server.

The three-tier design has some advantages over traditional two-tier or single-tier designs. Its modularity makes it easier to change or replace one tier without affecting the other tiers. It's also better for load balancing.

Three-Way Calling

A local phone company feature that allows a phone user to add another user to an existing conversation and have a three party conference call.

Three-Way handshake

The process whereby two protocol entities synchronize during connection establishment.

Three-Watt Booster

Optional equipment for use with a cellular phone car- mounting kit that raises a portable phone's maximum transmission power from 0.6 watts to 3.0 watts.

Three-Way Conference Transfer

A PBX feature. By depressing the switch hook, a user can dial another extension and either hang up and transfer the call, get information from the called party and then resume the first call or bridge all parties together for a three-way conference call.


The process whereby two protocol entities synchronize during connection establishment.


  1. The minimum value of a signal that can be detected by the system or sensor under consideration.

  2. Automatic call distributors allow the definition of several different thresholds that pertain to different objectives of your organization. For instance, thresholds can be defined for the maximum length of time a customer's call should wait in queue, how long an agent should spend on each call, and how many accepting the overflow.

  3. In England in the 1500s, the poor had dirt floors (hence "dirt poor), the wealthy had slate floors that would get slippery in the winter when wet, so they spread thresh (straw) on the floor to help keep their footing. As the winter wore on, they kept adding more thresh until, when you opened the door, it would all start slipping outside. A piece of wood was placed in the entranceway ” hence, a "thresh hold."

Threshold Of Pain

  1. The present price of local telephone service.

  2. Unbearable noise.


What happens when your Internet service provider decides you're getting too much bandwidth (aka speed) on your connection to the Internet. He cuts down the speed of your connection. He does this because he has other people or other services (e.g. email) he wants to provide higher speed service to. Or because he's simply short of a speedy connection to the Internet himself.

Through Dialing

Allows the attendant on a phone system to select a trunk and pass dial tone to a restricted phone user so that user may directly dial an outside call.


The actual amount of useful and non-redundant information which is transmitted or processed . Throughput is the end result of a data call. It may only be a small part of what was pumped in at the other end. The relationship of what went in one end and what came out the other is a measure of the efficiency of that communications network. Throughput is a function of bandwidth, error performance, congestion, and other factors. See also Goodput.


As in "throw a cable". To cut over. See Cutover.


How we type on our BlackBerrys and other small wireless devices ” those with tiny keyboards.

Thumb, Rule of

The Rule of Thumb of is derived from an old English law that stated a man could not beat his wife with anything wider than a thumb.


Describes the size of an image you frequently find on Web pages. Usually photo or picture archives will present a thumbnail version of its contents (makes the page load quicker) and when a user clicks on the small image a larger version will appear. Sometimes these links will be to a new page containing the larger graphic and other times right to the image directly.


A Microsoft Windows term for the transformation between 16-bit and 32- bit formats, which is carried out by a separate layer in the VM. the fundamental idea is to make older 16-bit programs work better in newer 32-bit operating systems.


Thuraya is the name of a commercial satellite service which delivers phone calls and other mobile communications services in parts of the Middle East, Asia, Africa and Europe. It started in in May 2001, It achieved a degree of fame when, in December, 2003, it was revealed that American intelligence penetrated Saddam Hussein's inner entourage before the 2003 Iraq war, finding one of his security aides who used a Thuraya satellite telephone, of the kind that American commanders favored. According to accounts circulating in Baghdad, Mr. Hussein personally executed the security man after the second of two pinpoint bombing strikes that nearly killed him, on March 20 and April 7, 2003. After that the use of satellite telephones by his entourage virtually stopped. Mr. Hussein was captured in December, 2003. Thuraya phones offer most of the features of normal cell phones, except that they use a constellation of satellites to provide service. Like all satellite phones, Thuraya's only work outdoors. Thuraya's "country" dialing code is +88216. Each Thuraya subscriber has an eight digit number. Thuraya phones have GPS. You can access the GPS features from the "GPS manager" submenu. After you figure where you are, you can send your coordinates to them via SMS (short message service) which the phone supports. Thuraya's carrier modulation is QPSK.


Terahertz (10 to the 12th power hertz). See also Spectrum Designation of Frequency.


Terrestrial Interference.


  1. Telecommunications Industry Association. TIA represents the telecommunications industry in association with the EIA (Electronics Industry Association). TIA represents companies, which provide communications materials, products, systems, distribution services and professional services in the U.S. and around the world. Activities include government relations, market support activities such as trade shows and trade missions, and standards development. TIA began as a group of equipment suppliers in the form of a committee of the USTA (United States Telephone Association, now known as the United States Telecom Association), splitting off in 1979 to form the USTSA (United States Telecommunications Suppliers Association). In 1988, the USTSA merged with the EIA/ITG (Information and Telecommunications Technologies Group of the Electronic Industries Association). TIA now operates under the umbrella of the EIA as the TIA/EIA, and works in conjunction with the USTA. TIA is accredited by ANSI (American National Standards Institute), and contributes voluntary standards to that body. In the Fall of 2000, the MultiMedia Telecommunications Association (MMTA), the successor organization to NATA, was fully integrated into the Telecommunications Industry Association.

    More recently and in connection with the privatization of its Part 68 responsibilities, the FCC selected TIA and ATIS (Alliance for Telecommunications Industry Solutions) as joint sponsors of the Administrative Council for Terminal Attachments (ACTA). ACTA responsibilities include adopting and publishing technical criteria for terminal equipment submitted by ANSI-accredited standards development organizations, and operating and maintaining a database of approved terminal equipment. See also ACTA, ACTAS, NATA, and Part 68. and

  2. Thanks In Advance.

TIA 568

Commercial Building Telecommunications Wiring Standard, July 91

TIA 568A

Commercial Building Telecommunications Cabling Standard, October 1995

TIA 569

Commercial Building Standard for Telecommunications Pathways and Spaces, Oct 90

TIA 569A

Commercial Building Standard for Telecommunications Pathways and Spaces, Aug 97

TIA 570

Residential and Light Commercial Telecommunications Wiring Standard, May 91

TIA 606

Administration Standard for the Telecommunications Infrastructure of Commercial Buildings .

TIA 607

Commercial Building Grounding and Bonding Requirements for Telecommunications.


The US Telecommunications Industries Association and Electronics Industries Association, which have merged. Now just called the Telecommunications Industry Association. See TIA for a full explanation.


See TIA/EIA IS-96.


IS-96 is the Speech Service Option Standard for Wideband Spread Spectrum Digital Cellular System, a new vocoder standard. The standard supports IS-95, the North American spread spectrum digital standard based on Code Division Multiple Access (CDMA), which was published in July, 1993. The engineering effort to produce IS- 96 was done in TIA Technical Subcommittee TR-45,5, Wideband Spread Spectrum Digital Technologies Standards. The specific vocoder described in IS-96 is a variable rate implementation, chosen because of its combination of high voice quality and low average transmission rate. The IS-96 vocoder provides variable vocoder rates depending on voice activity. This variability typically results in an average transmission rate of under 4 Kbps and yet provides for reasonably quality voice transmission. The IS-96 also provides a variable noise threshold which tracks and eliminates much of the background noise from the speaker's environment. You can get copies of both standards from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112.

TIA PN-2416

Backbone Cabling Systems for Residential and Commercial Buildings

Tiananmen Square

The largest public space in the world. It is five times the size of Moscow's Red Square. See 1949.


  1. An AT&T term for a digital carrier facility used to transmit a DS-1 formatted digital signal at 3.152 Mbps.

  2. Token-Ring Interface Coupler. An IBM device that allows a controller or processor to attach directly to a Token-Ring network. This is an optional part of several IBM terminal cluster controllers and front-end processors. See TIC CARD.

  3. See Telphony Interface Control.

TIC Card

Token Ring Interface Coupler is the IBM name for a variety of token ring adapter cards used to connect IBM controllers to token ring LANs. See TIC.


TICE was the mantra of PC Magazine and others in 1999 and 2000. It was the great sound echoing from the (very hollow) drums of Silicon Valley: "The Internet Changes Everything"


  1. A tick is an increment of time, as measured by a clock. The term refers to the audible sound of a mechanical clock or watch as it clicks away the seconds. Computer systems of all sorts have internal quartz clocks that manage and synchronize all system functions. A computer's clock speed in measured in MHz (MegaHertz, or millions of cycles per second), with each cycle also known as a tick. See also Clock Speed.

  2. A tick is a clock timer interrupt that causes a computer operating system to increment the system time in the DTS (Distributed Time Service) function of DCE (Distributed Computing Environment. See also DTS and DCE.

  3. A clock tick is a means of measuring time on a computer operating system. There are functions that report the number of milliseconds (ms) that have elapsed since the system was booted . The Windows operating system, for example, updates the function whenever there is a system clock tick, which is every 10ms.

  4. A tick mark is a mark plotted on a continuum, such as the axis of a graph. Tick marks are at regular, precise intervals in space, just as clock ticks are regular, precise intervals in time.

  5. Cisco defines ticks as the delay on a data link using IBM PC clock ticks (approximately 55 milliseconds).

Tick Tone

Clicking noise heard on some PBX lines indicating that the digits dialed will shortly be repeated to the central office.


A one-way telex machine used to typically report stock or commodity prices. The machine prints on ticker tape, which is about one inch wide and perfect for throwing out windows at passing celebrities . Thus the term "Ticker Tape Parade."


A telephone industry term for a filled-out form, usually a form for billing someone for a call. There are all sorts of tickets, including ones on paper, ones on computer and ones automatically generated without human intervention.


Temperature Induced Cable Loss. Pronounced " tickle ." A phenomenon in which the performance of fiber optic cables is adversely affected by low temperatures . The adverse impact is a multi-dB attenuation. What's strange is that the attenuation (i.e. reduction is signal strength) is localized so that it looks like a splice on an OTDR (Optical Time Domain Reflectometer, a test and measurement device often used to check the accuracy of fusion splices and the location of fiber optic breakers.) Particularly affected are cables which have been in place for at least one summer and which operate at relatively long wavelengths. Also particularly affected are cables which do not have a strong coupling between the central members (fiber cores) and the buffer tubes (protective individual fiber sheaths). The issue is that the glass fiber (expands and) contracts with changes in temperature, and to a different degree than does the buffer tube. The result is that of changes in the geometry of the fiber. TICL is a bad thing. What's difficult is fixing it, because the attenuation loss typically goes away when temperature rises, so that diagnosis is difficult ("like chasing ghosts" to use a colorful phrase). TICL is most likely to be troublesome when upgrading an existing link from single wavelength, e.g. 1310nm traffic to DWDM 1550nm traffic.


Terminal Identification. Used for all National-1 ISDN services, a two digit number between 00 and 62 entered after the SPID.


  1. Joining cables and/or wires together.

  2. Time Interval Error.

  3. Trusted Information Environment, an encryption scheme.

Tie Down

Verb meaning to terminate a wire on a main, intermediate or satellite distribution frame.

Tie Line

A dedicated circuit linking two points without having to dial the normal phone number. A tie line may be accessed by lifting a telephone handset or by pushing one, two or three buttons.

Tie Trunk

A dedicated circuit linking two PBXs.

Tie Trunk Access

Allows a phone system to handle tie lines which can be accessed either by dialing a trunk group access code or through the attendant.

Tied in the Wood

Term for wire that are placed in the wiring device but not terminated. Usually, wires are tied in the wood in preparation for coordinated termination. This refers to when wiring devices had wooden wire management strips .

Tier 1

Imagine a bunch of international Internet telephony carriers. Each one has POPs (Points of Presence) in several overseas cities. A POP consists of at least one PC containing some voice cards. When someone dials another country, their call goes across the Internet, reaches the PC at the distant POP. That PC recognizes the call as for that local city, grabs it, dials the local number and conferences the Internet call with a local dial-up call. This combination Internet/local phone call is theoretically cheaper than dialing directly across the world's telephone system. In order to provide seamless, cheap international calling over the Internet, you really need POPs in every major and minor city abroad. A number of Internet telephone companies have been banding together to create this international network. They're thinking about classifying themselves into various categories. For example a Tier 1 carrier would have over 50 POPs worldwide; have a network managed by a 7x24 NOC; have the ability to reroute and fall back to the PSTN if there is congestion or a hardware problem; have redundancy in terminating locations and have the ability to offer several levels of quality. Tier 2 might have fewer. It all hasn't been defined yet. But here's a definition a reader, Bill Coleman sent me: A Tier 1 telephone carrier has POPs in every city where there is a NFL football team. A Tier 2 telco would be a secondary market such as a city that gets bold print and a size 10 font in a Rand-McNally road atlas. A Tier 3 city would be one that nobody has really heard of unless you were born there. See also Back to Back Peering. To further confuse you, Infonetics Research, Inc. defines Tier 2 as National ISPs and CLECs that don't have fiber and regional ones that do.

Tier 2

See Tier 1.

Tier 3

See Tier 2.

Tiered Service

Telecommunications carriers and Internet service providers are eager to differentiate their network offerings. They sometimes do this by creating tiers of service. Tier 1 service, for example, is the best, and we all want to be Tier 1, if we can justify the additional cost. Some switches and routers allow network service providers to broaden their network service portfolios by creating multiple, differentiated QoS (Quality of Service) or GoS (Grade of Service) levels in order that they can offer tiered services. ATM naturally supports multiple Service Categories which differentiate between various native information streams, thereby providing each with the guaranteed QoS that he or she demands. Real- time, uncompressed voice, for example, is very demanding ” therefore, it is treated in the most effective manner. LAN-to-LAN traffic, on the other hand, expects nothing in terms of QoS ” therefore, it is treated on a "best effort" basis. IP networks are basically "best effort" networks, to begin with. However, there are proprietary mechanisms which can be embedded in logic programmed logic in the network switches and routers to differentiate between various packets, and, thereby, to deliver differentiated GoS. These mechanisms, which are contained in the IP packet headers, can be associated with individual customers, based on their port numbers, circuit IDs, or other identifiers. Tiered services let network service providers differentiate their offerings to segment existing markets and create new markets. There also are standards initiatives in development at the IETF (Internet Engineering Task Force) which will support standards-based GoS differentiation. At this time, it is not anticipated that IP networks will ever offer truly guaranteed QoS ” that's what sets ATM apart ” but differentiated GoS may well be good enough for most applications and most end user organization.


Time Independent Escape Sequence, a feature of modems.


Terminal Interface Node.


Tag Image File Format. TIFF provides a way of storing and exchanging digital image data. Aldus Corp., Microsoft Corp., and major scanner vendors developed TIFF to help link scanned images with the popular desktop publishing applications. It is now used for many different types of software applications ranging from medical imagery to fax modem data transfers, CAD programs, and 3D graphic packages. The current TIFF specification supports three main types of image data: Black and white data, halftones or dithered data, and grayscale data. Some wags think TIFF stands for "Took It From a FotograF." It doesn't.


Tagged Image File Format-Fax. A compression technique for sending faxes across an IP (Internet Protocol) packet data network. Fax image documents are attached to e- mail headers and are encoded in the TIFF-F compressed data format. In simple-mode, T.37 restricts fax transmission to the most popular fax machine formats, which specify standard resolution and page size. Simple-mode provides no confirmation of delivery. Full-mode provides for delivery confirmation.

Tiger Team

A group hired by an organization to defeat its own security system to learn its weaknesses.

Tiger Whiskers

In 16th- and 17th-century Peking, one took revenge against one's enemies by placing finely chopped tiger whiskers in their food. The whisker barbs would get caught in the victim's digestive tract and cause sores and infections.

Tight Buffer Fiber Optic Cables

Tight-buffered fiber optic cables use aramid strength members inside the cable instead of gel filling, as is the case with loose- tube gel-filled fiber optic cables. One of the advantages of tight-buffered fiber optic cables having aramid strength members along every inch of the cable is that the cable can be hung vertically and the fibers are still protected for the entire length of the cable. This is not the case with loose-tube gel-filled fiber optic cables because, when they are hung vertically, all the gel filling settles to the bottom and the optical fibers are no longer protected. Tight-buffered fiber optic cables also have buffer coatings (up to 900 microns) over each optical fiber cladding for added environmental and mechanical protection, increased visibility, and ease of handling. Tight-buffered fiber optic cables can be used indoors and outdoors which allows one cable to be used instead of having to switch cable types at the building entrance . This is different from loose-tube gel-filled cables because the gel is flammable and the cable must be spliced to indoor flame-retardant cables for runs into buildings. Therefore, according to manufacturers, tight-buffered fiber optic cables reduce labor, equipment and materials cost while improving system performance and reliability. See also Aramid and Tight Jacket Buffer.

Tight Jacket Buffer

A buffer construction which uses a direct extrusion of plastic over the basic fiber coating. This construction serves to protect the fiber from crushing and impact loads and to some extent from the microbending induced during cabling operations. See also Loose Tube Buffer.

Tightly Coupled

Describing the interrelationship of processing units that share real storage, that are controlled by the same control program and that communicate directly with each other. Compare with loosely coupled.

Tightly Coupled CPUs

Term used to describe multiple-processor computers in which several processors share the same memory and bus.




The tilde is the ~ sign, which you'll find on most keyboards. It looks like an arched eyebrow. Microsoft uses it in DOS to truncate a long Windows file name. Thus c:\my documents in Windows becomes c:\mydocu~1 in DOS. Other programs use it in different ways.


A surface segment of a furniture system panel, usually removable for access to cables or patch panels contained within the panel.


An unpleasant mosaic-like effect created by block-oriented video compression techniques like DCT (Discrete Cosine Transform), used in the JPEG (Joint Photographics Expert Group) standard. See DCT and JPEG.


Tilt is a factor that affects the maximum length of a metallic cable system. Tilt is a mathematical expression of the difference in attenuation (i.e., loss of signal power) between high frequency and low frequency signals over the entire length of a cable segment in a carrier band system. (Note: High frequency signals attenuate more quickly over distance than do low frequency signals.) Measured in decibels (dB), tilt is determined by N/(A1-A2), where N is the maximum allowable tilt, A1 is the attenuation of the high frequency signal, and A2 is the attenuation of the low frequency signal.


Teletyper Input Method. See Teleypre Input Method.


The quality of tone distinctive to a particular voice.


Time is critical to all forms of telecommunications. To understand why is simple. It takes time to send something from me to you. If I send you information encoded in bits and bytes, you have to have some way of figuring what I'm saying. There are basically two ways of sending information. You can send information in packets ” think paper envelopes. Those "envelopes" have my address and your address on them. And they're set up so it's clear what's the addresses and what's the message, etc. That takes extra bits. A faster way is to send the information in one gigantic fast stream. But that means that your computer and mine have to be exactly on the same time. And there's a huge business in making very precise clocks that synchronize flows of information. For more on this read the definitions for Asynchronous and Synchronous and the definitions following. Here's a fun fact on time: Most grandfather clocks with metal pendulums lose time in warm weather. This phenomenon occurs because most solids expand when heated. In the case of the clock, the higher temperature makes the metal pendulum longer, and thus slower.

Time-based Authoring Tool

A multimedia creation tool that uses time as a metaphor for building a project. Generally, objects are set up to happen at a certain time in a project, rather than in a certain place.

Time Assignment Speech Interpolation

TASI. A voice telephone technique whereby the actual presence of a speech signal activates circuit use. The result is clipping of the first bit of the speech, but more efficient use of the transmission facility. TASI is used on expensive circuits, such as long submarine cables. See TASI.

Time Call Hour Indicator

The hour at which the call was placed.

Time Call Minute Indicator

The minute within the hour at which the call was placed.

Time Congestion

The time resources (outgoing trunks) are busy.

Time Difference of Arrival

TDOA. A class of Position Determination Technology in which a mobile radio unit's position is calculated based on the reception time of its transmitted signal measured at three or more receiving sites. The distance from transmitter to receiver equals the propagation delay times the speed of light. However, the absolute propagation time is rarely known, leading to the use of time differences at the receiving sites. Employed in certain wireless E-911 solutions. See also E-911 and Angle of Arrival.

Time Divert To Attendant

A system feature which automatically transfers a phone to the attendant if the phone has been left off-hook too long.

Time Diversity

A method of transmission wherein a signal representing the same information is sent over the same channel at different times. Often used over systems subject to burst error conditions and with the spacing adjusted to be longer than an error burst.

Time Division Controller

TDC. A device which commands functions, monitors status and connects channels of TDM cards.

Time Division Multiple Access

  1. TDMA. A technique originated in satellite communications to interweave multiple conversations into one transponder so as to appear to get simultaneous conversations. A variation on TASI. A technique now used in cellular and other wireless communications. See TDMA.

  2. An RFID definition. A method of solving the problem of the signals of two readers colliding . Algorithms are used to make sure the readers attempt to read tags at different times. See RFID.

Time Division Multiplex

TDM. A technique for transmitting a number of separate data, voice and/or video signals simultaneously over one communications medium by interleaving a piece of each signal one after another. Here's our problem. We have to transport the freight of five manufacturers from Chicago to New York. Each manufacturer's freight will fit into 20 rail boxcars. We have three basic solutions. First, build five separate railway lines from Chicago to New York. Second, rent five engines and schlepp five complete trains to New York on one railway track. Or, third, join all the boxcars together into one train of 100 boxcars and run them on one track. The train might look like this: Engine, Boxcar from Producer A, Box Car from Producer B, Producer C, Producer D, Producer E, and then the order begins again...Boxcar from Producer A, Producer B...Moving one large train of 100 boxcars is likely to be cheaper and more efficient than moving five smaller trains each of 20 boxcars on five separate railway tracks. Time Division Multiplexing, thus, represents substantial savings over have five separate networks (five separate tracks) and sending five separate transmissions (five separate trains).

This is what Time Division Multiplexing is all about. And the analogy is perfect. Take one large train (fast communications channel) and interleave pieces (boxcars) from each conversation one after another. If you do this fast enough, you'll never notice you've broken the conversations apart, moved them separately, and then put them back together at the distant end. In TDM, you "sample" each voice conversation, interleave the samples, send them on their way, then reconstruct the several conversations at the other end. There are several ways to do the sampling. You can sample eight bits (one byte) of each conversation, or you can sample one bit. The former is called word interleaving; the latter bit interleaving. The basic goal of multiplexing ” whether it be time division multiplexing, or any other form ” is to save money, to cram more conversations (voice, data, video or facsimile) onto fewer phone lines. To substitute electronics for copper . See also the following three definitions.

Time Division Multiplexer

TDM. A device which derives multiple channels on a single transmission facility by connecting bit streams one at a time at regular intervals. It interleaves bits or characters from each terminal or device using the time. See Time Division Multiplex.

Time Division Signaling

Signaling over a time division multiplex system in which all voice channels share a common signaling channel, with time division providing the separation between signaling channels. See Signaling System 7.

Time Division Switching

The connection of two circuits in a network by assigning them to the same time slot on a common time division switched bus.

Time Division - Synchronous Code Division Multiple Access


Time Domain Reflectometer

TDR. A device that measures network cable characteristics such as distance, impedance, levels of RFI/EMI, connector and terminator problems, and the presence of opens and shorts. It uses radar-like principles to determine the location of metallic circuit faults.

Time Guard Band

A time interval left vacant on a channel to provide a margin of safety against interference in the time domain between sequential operations, such as detection, integration, differentiation, transmission, encoding, decoding, or switching.

Time Jitters

Short-term variation or instability in the duration of a specified interval.

Time Marker

A reference signal, often repeated periodically, enabling the correlation of specific events with a time scale. markers are used in some systems for establishing synchronization.

Time Multiplexed Switch

The space switch of which the cross point settings are changed in each time slot.

Time Notify

See TNotify.

Time Of Day Display

The time and date displays on phones. Actually, it's very useful information. Sometimes it's not displayed on the operator's console. As a result, the operator may never know that every phone in the office is showing the wrong time and date.

Time Of Day Routing

  1. This feature automatically changes access to certain types of lines at times when the lines change from being expensive to cheap, or vice versa. For example, it's cheaper to use WATS lines before 8:00 AM in the morning. A company has offices in New York and Los Angeles. It might be cheaper to route calls to Chicago in the morning over the tie lines to LA and then out the LA WATS lines to Chicago, than to go directly out the New York WATS lines. This is a way to allocate bandwidth for LAN traffic over corporate T-1 Networks. By programming T-1 multiplexers, customers can allocate the amount of T-1 bandwidth that can be used by voice, data, and LAN traffic on a time of day basis. For example, during the day, most of the T-1 bandwidth can be allocated for voice. At night, after employees go home, more bandwidth can be allocated to LAN and other computer data traffic so that file transfers can be done faster. This is particularly useful in IBM mainframe environments where large amounts of data needs to be transferred form remote offices/divisions to the headquarters.

Time Out

In telecommunications and computer networks, an event which occurs at the end of a predetermined interval of time is called Time Out. For example, if you lift the phone off the cradle and do not proceed to dial, after a certain number of seconds you will hear either a voice telling you to get on with it, a howling sound of some sort , or a fast busy signal. Data networks have the same thing. Don't do anything for x minutes and the system will knock you off the air, i.e., hang up on you. For example, your Internet session will time out at some point, if a device in the network (e.g., a router or a server) senses that no activity is taking place (i.e., no data packets are flowing in either direction. In more technical terms, time out is the amount of time that hardware or software waits for an expected event before taking corrective action by terminating the connection or session. This corrective action conserves network resources, which always are limited. See also Answer Supervision.

Time Sharing

A mode of operation that provides for the interleaving of two or more independent processes on one functional unit. Its most common use is the interleaved use of time on a computing system enabling two or more users to execute computer programs concurrently. Time sharing of computer resources is now relatively obsolete. See also Timesharing below.

Time Sharing Computer System

A computer system permitting usage by a number of subscribers, usually through data-communication subsystems. This is usually the case where the users have only dumb terminals that cannot process data by themselves the way a stand alone computer can. Computers are being joined together to deliver more computing power where it is most needed.

Time Sink

A consumer of our time. What happens to our personal time when things we do consume far too much of our time ” for example, listening to stupid recordings of distant automatic telephone systems present us mindless requests: Dial 1 if you live in Northern Illinois. Dial 2 if you live in Southern Illinois, etc.

Time Slice

In a multi tasking environment, each task is allotted a portion of the CPU's overall processing power. This portion is called a time-slice. And it's usually measured in milliseconds. The CPU switches between tasks, and those with higher priority receive more time-slices than lower-priority tasks. See Time Slicing.

Time Slicing

The term used to describe the dividing of a computer resource so multiple applications or tasks requesting the resource are allocated some amount of the resource's time. See Time Slice.

Time Slot

  1. In time division multiplexing (TDM) or switching, the slot (brief moment in time) committed to a voice, data or video conversation. It can be occupied with conversation or left blank. But the slot is always present. You can tell the capacity of the switch or the transmission channel by figuring how many slots are present. See also TDM.

  2. An SCSA term. The smallest switchable data unit on the SCbus or SCxbus Data Bus. A time slot consists of eight consecutive bits of data. One time slot is equivalent to a data path with a bandwidth of 64 Kbps. See S.100 and SCSA.

Time Slot Assignment

TSA. The assignment of a time slot in a forward time division multiplexed (TDM) facility in order to accommodate traffic from a tributary TDM facility, or in reverse. TDM-based transmission requires that time slots be committed across the network, from end-to-end. Therefore, it is essential that time slots be assigned by the various multiplexers that interconnect TDM circuits. Time-slot assignment enables traffic to be added to any circuit from any tributary, or to be dropped from any circuit to any tributary. The term is most commonly used in the SONET domain. See also SONET, TDM, Time Slot, and Time Slot Interchange.

Time Slot Interchange

TSI. The interchanging of time slot between TDM-based links. If the timeslot committed to a given transmission (i.e., call) on an incoming tributary link is already assigned to another transmission on the outgoing link to which it connects, another time slot is selected and assigned. The term is most commonly used in the SONET domain. See also SONET, TDM, Time Slot, and Time Slot Assignment.

Time Space Time System

TST. The most common form of switching matrix for small digital telephone exchanges in which a space switch is sandwiched between two time switches.

Time Switch

A device incorporating a clock which arranges to switch equipment on or off at predetermined times.

Time T

December 31, 1996, 2359 hours UTC (Universal Time Coordinated). The exact time when the maximum digit length allowed in international dialing was increased from 12 to 15 digits. It seems silly to be so precise about such a thing, but the Time T deadline marked the beginning of the expansion of the number of digits within the numbering plans of the various countries around the world. All of the switches in the networks had to be reprogrammed to understand the lengthened dialing plan, or else the new numbers could- n't be processed. Some switches were reprogrammed, but lots were not. We needed a lengthened dialing plan because we are running out of telephone numbers, and for a bunch of reasons. Blame it on fax machines, cell phones, and pagers. For that matter, blame it on me; my family of four has 18 separate telephone numbers, including fax lines, modem lines, pager ( beeper ) lines and cell phones, For that matter, blame it on your family; they probably have as many as I have. See also NPA and UTC.

Time To Live

TTL. A mechanism used in the IP protocol, the TTL is an eight-bit field in the IP header. TTL begins at 255 (2 raised to the power eight minus one) seconds, as the TTL field in the IP header is eight bits wide, and as the value of "00000000" is the TTD (Time To Die). As an IP packet is accepted in the buffer of a switch or router, the TTL is decremented until it exits that device. This happens again and again, until either the packet reaches its destination, or until the TTL is decremented to the "00000000" value and it is killed. Without the TTL mechanism, errant packets would circle forever in a "closed loop" and the Internet (or other IP-based network) would be brought to its knees.

Time Varying Media

An SCSA definition. Time-varying media, such as audio data (as opposed to space-varying media, such as image data). See S.100.

Time Zone Calling

The ability of a dialing system to start and stop calling at predetermined times to different time zones.


Any of several addressing standards used to interlock and sequence audio and video information.

Timed Detection

As a substitute for answer supervision, some long distance phone companies use call timing and estimate that a call is completed if the caller remains off- hook for 30 seconds or more. This is not necessarily accurate, of course. The caller might be holding, thinking the person is in the shower, out in the garden, etc. Little does the caller know he is now being charged to listen to ringing signals. A long distance phone company that is "equal accessed" doesn't have this problem. A long distance company that isn't equal accessed ” one that you have to dial directly with a local call ” might well have this problem. Rule: When in doubt, don't wait too long on the phone listening to endless ringing. Hang up. Count to ten. Then redial.

Timed Purge

A feature of interactive voice response systems, especially fax-back systems. If the document isn't requested for x number of days or weeks or if the document ages to a certain point, the system automatically deletes the document.

Timed Recall

Your PBX can be instructed to place a call at a designated time. When the time comes, your PBX rings your phone. When you answer your phone, the PBX places the call.

Timed Reminders

At 20-second intervals, timed reminders will alert an attendant that a call is still waiting, a called line has not yet been answered or a call is still on hold. Timed reminders can be made longer or shorter. They can alert attendants to all sorts of events and non-events .


Two computers are "talking" on a network. One (for any reason) fails to respond. The other computer will keep on trying to communicate with the other computer for a certain amount of time, but will eventually "give up." This is called timeout. A timeout also happens in a single standalone computer. If a device (e.g. a printer) is not performing a task or responding, the computer will wait before figuring that something wrong has happened . That time period is called timeout.

Times T

A new, expanded dialing plan developed by the ITU-T. Times T increases the maximum number of dialed digits from the current 12 to 15, plus the three-digit international access code (country code).


The use of one computer by many users at one time. Each user is typically sitting in front of a data terminal and connected to the master computer through communications lines ” local or long distance. The user asks the computer to work on his task, whether it be a simple as looking up some stock prices, checking an airline reservation or doing some accounting calculations. It appears to each user as if he/she has a computer dedicated to his own task, but the computer is large and powerful, and is moving rapidly from one user's task to the next. Timesharing's advantages are twofold:

  1. The user may find it cheaper to time share a computer than to buy his own.

  2. The computer may have valuable and extensive information in it, which would be virtually impossible to duplicate or handle in many stand-alone computers. Timesharing was more popular when computers were more expensive.

Timeslot Management Channel

TMC. A dedicated channel for sending control messages used to set up and tear down calls in a T-1 frame. In a GR-303 interface group, the primary TMC is usually in channel 24 of the first DS1, while a redundant TMC (if used) would be located in a different DS-1.


A mark placed on a data or voice transaction used for throughput and processing calculations. Can be used to determine total work time by placing one at the beginning and one at the end of a transaction. Timestamps are used in productivity measurement, in call accounting and traffic analysis systems, and a wide variety of other applications. Timestamps also are used to synchronize various network devices, such as IRC (Internet Relay Chat) servers.


In the beginning, telephone systems were very simple, circuit-switched animals. When I called you, we used the entire bandwidth on the wires for our conversation. If something untoward happened, one of us would simply ask the other to repeat what he said. No sweat. Quickly it became apparent to the phone industry that devoting an entire circuit to one conversation was wasteful. So various methods to put more than one conversation on a circuit was devised. These were initially called multiplexing techniques. The early ones were typically analog, with different conversations occupying different frequencies. Filters could easily pull the various conversations out. But then came the digital revolution, which made it suddenly cheap to represent phone calls by bits and mush many conversations into one large stream of bits. (The original digital channels are originally thought of purely as "pair gain.") How to pull the various conversations out of that one gigantic bit stream? Think T-1 with a stream of 1.544 million bits per second, or 24 conversations each encoded at 64,000 bits per second. How to figure out where one conversation started and ended? You could add information to the flow. Call it "framing" information. That information would frame the data. If you know what the frame looked like, you could pluck the information out of it. The T-1 trunk's 24 channels of 64,000 bits per second, each carrying 8,000 8-bit bytes per second. Each byte represented one sample of analog information. The remaining 8,000 bits per second were framing bits (24 x 64 = 1,536,000 bits per second plus 8,000 bits per second = 1,544,000 bits per second. In the beginning each T-1 was an entity unto itself and it typically started and ended in analog loops at either end. Initially, T-1 was an asynchronous system. Each pair of end terminals ran at their own clock rate, and each terminal used its receive timing to demultiplex the incoming signal. The transmit and receive sides were independent of one another. Unfortunately, the voice quality of these analog-end and often analog-middle networks proved to be less than desirable due to the low bandwidth and losses of the analog channels. And the networks of lonely pair gain digital systems suddenly started to get more and more complex and more intertwined. It was increasingly evident that the bits and pieces of a digital networks had to become one gigantic synchronized network. So follow this evolution: When digital channel units were introduced (to bring T-1 channels right to the user's site without the disadvantage of convergence to analog), one end terminal was designated as the master and had its own timing reference. The other end terminal was a slave, and derived timing for its transmit side from the data being received (looped timing). This arrangement worked as long as the end terminals were no more complex than a channel bank. But T-1 (DS-1) was only the beginning. Soon T-3 (DS-3) came along, with speeds of 45 million bits per second (672 voice conversations). And switches became digital, plucking straight digital bit streams right out of the T-1 bit stream. Digital switches with DS-1 port interfaces exemplified the shortcomings of an asynchronous system. If the two switch clocks were not at the same frequency (i.e. their clocks were out of whack), the data would slip at a rate dependent on the difference in clock frequencies. A slip is defined as a one frame (193 bits) shift in time difference between the two signals in question. This time difference is equal to 125 microseconds. Slips were not considered a major impairment to trunks carrying voice circuits. The lost frames and temporary loss of frame synchronization resulted in occasional pops and clicks being heard during the call in progress. However, with advances in DS-1 connectivity, these impairments tended to spread throughout the network. To minimize these problems (and to allow for efficient ” i.e. error-free transmission of data), a hierarchical clock scheme was developed, whose function was to produce a primary reference for distribution to switching centers in order to time the toll switches. Local switching in that early era was primarily analog, so that synchronization was not required at the end offices. Later, digital switches and direct digital services or networks (DDS or DDN) became common at the end offices (i.e. those directly serving the customer and providing digital services to customers. This meant timing had to be distributed to local levels.

The resulting hierarchy evolved into four levels. Level 1, known as Stratum 1, is the primary reference. It was known originally as the Bell System Reference Frequency or BSRF. The second level, Stratum 2, is used at toll switches. Stratum 3 is used at local switches. Channel banks and end terminals that use simple crystal oscillators are known as Stratum 4 devices. Recently, SONET (Synchronous Optical Network) networks have created the need for a clock stratum level better than Stratum 3, which is called Stratum 3E.

In 1984, when the Bell System broke up into the local service providers and the long distance carriers, the timing hierarchy became less well defined. Now each local company could no longer take its timing from the long distance carrier, but had to engineer a system, either a hierarchy or otherwise, to distribute timing to their offices. This made everything more difficult because failures in the transmission systems could cause "islands" or areas without a reference to Stratum 1. For more on timing, see See also Timing Advance.

Timing Advance

See Location Services.

Timing Jitter

Deviation of clock recovery that can occur when a receiver attempts to recover clocking as well as data from the received signal. The clock recovery will deviate in a random fashion from the transitions of the received signal.

Timing Recovery

The derivation of a timing signal from a received signal.

Timing Signal

The output of a clock. A signal used to synchronize connected equipment.

Timing Slip

A sudden timing delay change during high-speed digital transmission often caused by using T-1 carriers from different suppliers.


Transmission Impairment Measurement Set. It is a basic analog testing set. In common usage it refers to the suite of fundamental tests required to ensure that a telecom circuit will support analog traffic.


Telecommunications Information Networking Architecture. A developing standard which is intended to resolve issues of integration between TMN (Telecommunications Management Network) and IN (Intelligent Network) standards and concepts. TINA focuses on the definition and validation of an open architecture for worldwide telecom services through a flexible software architecture for both end-user and network management services. See TINA-C, TMN and IN.


Telecommunications Information Networking Architecture Consortium. An international, voluntary, not-for-profit organization of vendors and others for the purpose of promoting an open network architecture for the delivery and management of sophisticated services.


Also known as a finger. An individual digital channel of a wireless rake receiver. A rake receiver can support a number of tines, which can be combined to form a stronger received signal.


The dongle that fits between a PCMCIA card inside your laptop and the RJ-45 cable that is typically used to connect to your local area network.

Tinned Wire

Copper wire coated with tin to make soldering easier.

Tinsel Town

Hollywood. The nickname "Tinsel Town" was coined by Oscar Levant, the pianist, and composer who observed : "Strip the phoney tinsel off Hollywood, and you'll find the real tinsel underneath."

Tinsel Wire

A component of some phone line cord conductors. Tinsel wire is made by rolling copper into very thin, narrow rolls and then winding several strands of tinsel around a non-metallic core (a string) and then placing an insulating cover over the resulting conductor. A cord is then built up of two or more conductors encased in a plastic jacket. The essential reason for this type of construction is to obtain good cord flexibility and long life.


Another name for hue.


  1. The first wire in a pair of phone wires. The second wire is called the "ring" wire. The tip is the conductor in a telephone cable pair which is usually connected to positive side of a battery at the telephone company's central office. It is the phone industry's equivalent of Ground in a normal electrical circuit. See Tip & Ring.

  2. TIP. The Transaction Internet Protocol protocol ensures that multivendor transaction monitors will work with one another to complete transactions over the Internet (RFC 2371). TIP came from a joint Microsoft/Tandem effort. See Transaction Internet Protocol for a much longer explanation.

Tip & Ring

An old fashioned way of saying "plus" and "minus," or ground and positive in electrical circuits. Tip and Ring are telephony terms. They derive their names from the operator's cordboard plug. The tip wire (the positive wire) was connected to the tip of the plug, and the ring wire (the negative wire) was connected to the slip ring around the jack. A third conductor on some jacks was called the sleeve. See Tip, Ring & Ground.

Tip Cable

A small cable connecting terminals on a distributing frame to cable pairs in the cable vault.

Tip Conductor

The conductor of a pair that is grounded at the central office when the line is idle. This term was originally coined from its position as the first (tip) conductor of a tip-ring-sleeve switchboard plug. See Tip & Ring.

Tip Side

That conductor of a circuit which is associated with the tip of a plug, or of a telephone circuit. See Tip & Ring.

Tip, Ring, Ground

The conductive paths between a central office and a phone. The tip and ring leads constitute the circuit that carries the speech or data signal. The ground path in combination with the conductor is used occasionally for signaling.


Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON). An ETSI (European Telecommunications Standards Institute) project to define the interactions between emerging VoIP (Voice over Internet Protocol) packet technologies and traditional circuit-switched voice networks. TIPHON is intended to ensure that VoIP networks will interface smoothly with the PSTN (Public Switched Telephone Network), as well as the GSM and other wireless networks. TIPHON is trademarked by ETSI.


Telephone Industry Price Index.


Telrate International Quotations.


Trunks Integrated Records Keeping System. An Operations Support System (OSS) developed many years ago by the Bell System to mechanize circuit provisioning functions including circuit order control, circuit design, selection and assignment of equipment and facilities, work order generation and distribution, and circuit inventory control. TIRKS maintains inventory information on all assignable components for trunks and special-service circuits. The Plug-in Inventory Control System/Detailed Continuing Property Records (PICS/DCPR) system maintains records of plug-in equipment, and interfaces with TIRKS in the circuit-provisioning process. TIRKS is still used by the RBOCs (regional bell operating companies).


Technical Information Sheets.


On December 21, 1993 Vice President, Al Gore, told the National Press Club in Washington, "There is a lot of romance surrounding the sinking of the Titanic 81 years ago. But when you strip the romance away, a tragic story emerges that tells us a lot about human beings ” and telecommunications. Why did the ship that couldn't be sunk steam full speed into an ice field? For in the last few hours before the Titanic collided, other ships were sending messages like this one from the Mesaba: "Lat42N to 41.25 Long 49W to Long 50.30W. Saw much heavy pack ice and great number large icebergs also field ice." And why, when the Titanic operators sent distress signal after distress signal did so few ships respond?

The answer is that ” as the investigations proved ” the wireless business then was just that, a business. Operators had no obligation to remain on duty. They were to do what was profitable. When the day's work was done ” often the lucrative transmissions from wealthy passengers ” operators shut off their sets and went to sleep. In fact, when the last ice warnings were sent, the Titanic operators were too involved sending those private messages from wealthy passengers to take them. And when they sent the distress signals, operators on the other ships were in bed."


Titanium resists corrosion for 100 years. It's as light as aluminum and as a strong as steel . It's also expensive and it's now "way cool." The titanium-clad Guggenheim Museum in Bilbao, Spain made the town a major tourist attraction. When I saw it in 2001, I flipped .


The Bell Atlantic Telecom Industry Services Operating Center. It provides standards, methods and procedures and services to the full spectrum of CLECs from full service providers to wholesale providers.


In the language of multimedia, when an author sells what he or she has created, it is called a title. The encyclopedias, dictionaries, musical works, and games available on CD are all "titles." Someone authors the material, and sells it to users who can play it back but not change the content.


The dot on top of the letter "i" is called a "tittle." Tittle is Latin for something very small.


Touch-tone central office (CO) trunk.


Touch tone.


Test Jack Frame.


Journal Recovery Table.


  1. Tie Line.

  2. Transmission Level.


Transaction Language 1. A machine to machine communications language which is a subset of ITU-T's man machine language.


Three Letter Acronym. A form and usage common to our acronym-happy industry.


Test LoopBack. A CSU (Channel Service Unit) operating mode that loops the telco's T-1 transmission facility back towards itself at itself at the same time it loops the CPE back toward itself.


Top Level Domain. See Domain and gTLD.


A Temporary Local Directory Number is assigned by a visited wireless network's Mobile Switching Center to support call delivery to an idle roaming subscriber. This TLDN is used by the originating MSC (Mobile Switching Center) to establish a voice path to the serving MSC via existing interconnection protocols (i.e. SS7).


Terminating Local Exchange Carrier.


  1. Trunk Link Frame.

  2. Resource Management Table.


Transport Layer Interface. TLI. An application program interface provided with UNIX System V Release 3.


Logical Line Table.


  1. Transmission Level Point. A physical point in a circuit at which the signal level, or amplitude, is measured. See also dBrn, Level, Loss, and Pad.

  2. Logical Line Pair Table.


Transparent LAN Service. You have a LAN in one office. Across town you have another office with another LAN. You go to your friendly service provider and say "I want a telecommunications service that will let me send messages, mail and files, etc. between my two LANs." Bingo, they provide you a Transparent LAN Service (TLS), which is a high speed VPN (Virtual Private Network) service that hides the complexity associated with the WAN (Wide Area Network. With TLS, a service provider interconnects a corporation's LANs in such a way that the wide area is transparent to the end user. It is as though the physically separate LANs were all physically connected in the same physical location. Actually, they are logically interconnected across the WAN.

A loosely-defined high speed VPN (Virtual Private Network) service offering of various LECs (Local Exchange Carriers), IXCs IntereXchange Carriers) and MSPs (Metropolitan Service Providers), TLS provides for the interconnection of LANs over the MAN or WAN public data network (PDN). In other words, a TLS customer can establish direct Ethernet-to- Ethernet or Token Ring-to-Token Ring connectivity through a PDN without either the trouble or expense associated with a private leased-line network, or even a Frame Relay or ATM network. Internally, the carrier may provision the network through a variety of methods. Transmission facilities may be in the form of optical fiber or xDSL (e.g., ADSL, HDSL, or SDSL) for access, and will be optical fiber in the backbone. At Layer 1, the optical fiber may run the SONET protocol, although it may be DWDM. At Layer 2 and 3, various combinations of GbE (Gigabit Ethernet) and 10GbE, IP, Frame Relay, ATM, MPLS, and other protocols may be employed. In any event, all of these protocol issues are transparent to the end user organization. TLS generally is provisioned as a managed service, with the service provider retaining full ownership of and taking full responsibility for all of the technical issues, including the CPE (Customer Premises Equipment). It looks like straight Ethernet to you, although generally at a slower speed. See 10GbE, ADSL ATM, CAP, CPE, DWDM, Ethernet, Frame Relay, GbE, HDSL, IP, IXC, LEC, MPLS, MSP, SDSL, SONET, Token Ring, VPN, and xDSL.


  1. Trouble Management. The responsibilities associated with receiving any network events that impact customer service whether they are generated via customer contact or from internal network elements. Trouble Management tracks all problems, groups them together (if possible), and relays trouble tickets for problem resolution. A mobile phone term.

  2. Traffic Management. As an ATM term, traffic Management is the aspect of the traffic control and congestion control procedures for ATM. ATM layer traffic control refers to the set of actions taken by the network to avoid congestion conditions. ATM layer congestion control refers to the set of actions taken by the network to minimize the intensity, spread and duration of congestion. The following functions form a framework for managing and controlling traffic and congestion in ATM networks and may be used in appropriate combinations.

    • Connection Admission Control

    • Feedback Control

    • Usage Parameter Control

    • Priority Control

    • Traffic Shaping

    • Network Resource Management

    • Frame Discard

    • ABR Flow Control


Terminal Multiplexer.


Telecommunication Managers Association.


A piece of software announced by Northern Telecom (now called Nortel Networks) in the summer of 1994 and designed to map Windows Telephony commands to Novell Telephony Services (TSAPI) commands. Tmap runs on the local workstation (also called client) and translates TAPI commands into TSAPI commands that are sent through the local area network to the telephony file server and thence to the PBX, causing the PBX to dial, or conference or ring a phone, etc. The idea is that computer telephony software running on the user's desktop PC could be implemented as easily through a card in the PC or through the company PBX attached to the LAN ” and the whole process would be seamless to the user.


Timeslot Management Channel. A dedicated channel for sending control messages used to set up and tear down calls in a T-1 frame. In a GR-303 interface group, the primary TMC is usually in channel 24 of the first DS1, while a redundant TMC (if used) would be located in a different DS-1.


Telocator Message Entry. A client/server protocol proposed for use in communications between wireless pagers and the Internet. TME is proposed as a replacement for Simple Network Paging Protocol (SNPP). See also SNPP.


See TeleManagement Forum.


Telecommunications Main Grounding Busbar. A busbar placed in a convenient and accessible location and bonded by a means of the bonding conductor for telecommunications to the service equipment (power) ground. l




  1. Multilink Control Table.

  2. See Telephony Markup Language.


Telecommunications Management Network. A network management model defined in ITU-T recommendation M.30 and related recommendations, and intended to form a standard basis for management of advanced networks such as SDH (Synchronous Digital Hierarchy) for fiber optics in land lines and GSM (Global System for Mobile Communications) in the cellular world. TMN specifies a set of standard functions with standard interfaces, and makes use of a management network which is separate and distinct from the information transmission network. Further, standard network protocols such as the OSI CMIP (Open Systems Integration Common Management Information Protocol) are specified. Implementation of this concept involves the linking of all subject device elements to OMCs (Operation and Maintenance Centers) which, in turn, are linked together over a separate network. A centralization occurs to facilitate control, monitoring, and management of all devices in the communications network, which can include legacy systems as well as newer technologies. Operation systems functions include the full range of functions defined in the OSI model: Performance Management (PM), Fault Management (FM), Configuration Management (CM), Accounting Management (AM), and Security Management (SM).

A gentleman called James Keil who wrote his master's thesis at the University of Boulder, Interdisciplinary Telecommunications Program, on TMN compliant equipment, says that a "quick and dirty definition of TMN" would be "A network management standard which seeks to provide IT, business and network service management in a multi-domain environments (i.e. VPN, RBOC, Cellular providers)." Mr. Keil also says TMN fully implemented can retrieve resources from disparate networks like SNMP, through the use of managed objects or ANSI.1. TMN has much more functionality than SNMP. See also TINA.


Test Management Protocol: As an ATM term, it is a protocol which is used in the test coordination procedures for a particular test suite.


Trunked Mobile Radio. Another name for SMR (Specialized Mobile Radio). See SMR.


Traffic Measurement and Recording System.


  1. Time Multiplexed Switch. In the AT&T 5ESS switch CM, the TM provides switch paths between switching modules and passes control messages to and from the message switch, and functions as the hub for clock distribution to the switching modules.

  2. TOPS Message Switch.

  3. Trouble Management System.

  4. Transmission Measuring Set.


Temporary Mobile Station Identifier A mobile station identifier (MSID) sent over the air interface and is assigned dynamically by the network to the mobile station.


Terminal MakeUp. Refers to the electrical configuration (resistance including bridged tap) of the terminal. It is a function of the linear distance (usually measured in feet) from the Central Office and copper cable gauge (or gauges) and bridge tap.




  1. Telephone Number.

  2. Twisted Nematic. Most used display technology for calculators , watches and measuring equipment. TN uses liquid crystals sandwiched between two plates of glass with integrated transparent electrodes which can be made transparent and non-transparent by applying an electric current to them. See LCD.


Delivery of a 3270 data stream via Telnet, provided as part of the TCP/IP protocol suite.


Tits and Ass ” an irreverent name for a TV channel called the Spike Channel, which was once called TNN.


A small connector used on coaxial cable, commonly used for cellular antennas, and some data and test equipment.


Terminal Net Loss.


Time Notify. Specifies how often SMT initiates neighbor notification broadcasts. See also SMT.


A protocol used to send paging messages from terminal to terminal on LANs and WANs over a wire circuit.


  1. Transit Network Selection. As an ATM term, it is a signaling element that identifies a public carrier to which a connection setup should be routed.

  2. Transient Network Signaling

  3. Network Status Table.


Non-Synchronous test line provides for rapid testing of ringing, tripping and supervisory functions of toll completing trunks. This test line provides an operation test which is not as complete as the Synchronous test but which can be made more rapidly.


  1. Test and Turnup. This is the end phase of the circuit installation and provisioning process.

  2. Network I/O Device Table.


Transmit Only.


Type Of Address/Numbering Plan Identifier.


Technical Operating Center.


Time Of Day.


The king of stockbrokers, but the peasant of tennis players. Todd Kingsleyism include such gems as "When in doubt, stay out." "A broken clock is right twice a day."


Time Out Factor: As an ATM term, it is an ABR service parameter, TOF controls the maximum time permitted between sending forward RM-cells before a rate decrease is required. It is signaled as TOFF where TOF=TOFF+1. TOFF is a power of 2 in the range: 1/8 to 4,096.


Time Out Factor: See TOF.


  1. A flip-flop switch that changes for every input pulse.

  2. Any simple two-position switch.


Transport Overhead. A SONET term describing an element of signaling and control. TOH includes Section Overhead (SOH) and Line Overhead (LOH).


Test Okay.


  1. In networking, a unique combination of bits used to confer transmit privileges to a computer on a local area network. It also carries important information for routing messages over the network, such as source and destination addresses, access control information, route control information, and date checking information. When a LAN-attached computer receives a token, it has been given permission to transmit. On a token ring network, the token is 24 bits long. See Token Passing and Token Ring.

  2. Here is a Rolm definition: The floating master message which coordinates use of the CBX control packet network among the nodes connected to it.

Token Bus

A local network access mechanism and topology in which all phones or workstations attached to the bus listen for a broadcast token or supervisory frame. That token confers on them the right to communicate over the share channel, the token bus. An example of a Token-Bus is IEEE 802.4. See Token Passing.

Token Latency

The time it takes for a token to be passed around the local area network ring.

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