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A glossary of computer and telephone terms. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Procedure used in most T-1 transmission links where one bit, robbed from each of the 24 subchannels in every sixth frame, is used for carrying dialing and controlling information. A type of in-band signalling used in T-1 transmission. A & B signalling reduces the available user bandwidth from 1.544Mbps to 1.536 Mbps. ADSL Asymmetric Digital Subscriber Line. A revolutionary method of compressing and multiplexing data on a POTS line PSTN network. ADSL is currently offered by Bell Canada as a 64kbps upstream and 1.54Mbps downstream facility over standard long copper links. Bandwidth as high as 52Mbps has been promised. The future of ADSL is in part that it presents a more direct migration path to ATM, than does ISDN. ADSL, on the surface, providing transparent data pipes at various rates over POTS. To create multiple channels, ADSL modems divide the available bandwidth of a telephone in one of two ways: Frequency division multiplexing (FDM) or echo cancellation. FDM assigns one band for upstream data and another for downstream data. The downstream datapath is then divided by time division multiplexing into one or more high-speed channels and one or more low-speed channels. The upstream path is also multiplexed into corresponding low speed channels. Echo cancellation assigns the upstream band to overlap the downstream, and separates the two by means of of local echo cancellation, a technique well known in V.32 and V.34 Modems. Echo cancellation uses bandwidth more efficiently, but at the expense of complexity and cost. With either technique, ADSL splits off a 4KHz region for POTS at the DC end of the band. An ADSL modem organizes the aggregate data stream created by multiplexing downstream channels, duplex channels, and maintenance channels together into blocks, and attaches error code to each block. The receiver then corrects errors that occur during transmission up to the limits implied by the code and the block length. The unit may also be set to create super-blocks by interleaving data within sub-blocks; this allows the receiver to correct any combination of errors within a specific span of of bits. Initial trial indicate that the correction used in ADSL will create effective error rates suitable for MPEG2 and other digital video compression technologies. A-Law The PCM coding and commanding standard used in Europe. The method of encoding sampled audio waveforms used in the 2.048Mbit 30 channel PCM primary system, widely used outside North America. ACD Automatic Call Distribution. A system which passes callers to an open line. Often adjoining Private Branch Exchange (PBX) switches. Aliasing Distortion in a signal. In video when sampling rate interferes with the frequency of program material. Spectral aliasing is caused by interference between the luminance and chrominance signals. ANI Automatic Number Identification is a Telco service (similar to CallerID) which allows a recipient to determine the number of the caller before the call goes through. ASCII American Standard Code for Information Interchange. is a 7-bit coding scheme used by small computers for converting letters, numbers, punctuation and control codes into digital form. Asynchronous Transmission A method of data transmission which allows characters to be sent at irregular intervals by preceding each character with a start bit, and following it with a stop bit. It is the method most small computers (especially PCs) use to communicate with each other and with mainframes today. ATM Asynchronous Transfer Mode is a cell-switching and multiplexing technology designed to combine the benefits of circuit switching (constant transmission delay, guaranteed capacity) with those of packet switching (flexibility, efficiency for intermittent traffic). Like X.25 and Frame Relay, ATM defines the interface between the user equipment and the network. ATM differs from synchronous transfer mode methods, where time-division multiplexing techniques are employed to preassign users to time slots. ATM time slots are made available on demand, with labels identifying the source of the transmission contained in each ATM cell. Attenuation The decrease in power of a signal, light beam, or lightwave, either absolutely or as a fraction of a reference value. Usually occurs as a result of absorption, reflection, diffusion, scattering, deflection or dispersion from an original level and not normally from geometric spreading (i.e., the inverse square of distance effect). Attenuation is measured in decibels (dB), and is the opposite of gain. ANI Automatic Number Identification is a service, analog or digital, which passes through the phone number of the caller before the recipient picks up the phone. ANI is touted as a compelling service of ISDN, although really an attribute of Signalling System 7 (and therefore distinct from ISDN) and one can get ANI from other Telco services such as Switched 56k or Centrex. ANI is becoming synonymous with Caller ID. Or bearer channel, is a fundamental component of ISDN interfaces. It carries 64,000 bits per second in both directions (duplexed), is circuit switched and is able to carry either voice or data. Whether it does or does not depends on how your Telco has tariffed its ISDN service. Bandwidth The number of bits of information which can move over a communications medium in a given length of time. Basic Rate Interface An ISDN service package which includes 2 B or Bearer channels (full duplex @ 64k bps) and one D or Data channel at 16kbps. Commonly referred to as 2B+D. Ideal for SOHO CT applications because of tip-ring connectivity. Baud The measure of transmission speed over an analog phone line. The number of changes per second in the analog sine wave carrier signal (3kHz). Often confused with bits per second. See Modem. A Telco leased service from the local CO, which typically includes intercom, call forwarding, call transfer, toll restrict, least cost routing and call hold on single lines. CGI Common Gateway Interface. It defines a method for a Web server and an outside program, such as a database, to share information through on-line forms and gateways. CAS As in CAS compliant. A Communicating Applications Specification is a high-level programming interface developed by DCA and Intel. This standard permits fax boards to offload data processing (such as rasterizing an image) from a CPU drastically accelerating the transmission process of sending a fax. CISC Complex instruction set computers use long instructions with longer clock cycles and lower scaling to process data. Clustering A method of super-computing that involves connecting groups of computers to share in compute tasks and processes. Synonymous to networked, preemptive multitasking. Most commonly used in digital animation studios instead of massively parallel supercomputers. CO Central Office of a Telco. Usually a nexus or main node consisting of switching and head-end equipment. Connects subscribers' lines to other lines local and long distance. Sometimes referred to in Europe as Public Exchange. Computer Telephony CT is a term which describes the industry that concerns itself with applying computer electronic data processing and transaction services to telecommunications devices and systems, especially switches and phones. It is a primary component of Salesforce Automation (SFA). CSU Channel service units are used to connect a digital phone line (T-1 or Switched 56 line) coming in from the Telco to either a multiplexer, channel bank directly to another device producing a digital signal, i.e., a digital PBX, a PC or other data communications device. CSUs perform line conditioning equalization functions and respond to loop back commands. Dialed Number Identification Service is a feature of 800 and 900 lines that provides the number the caller dialed to access the attached CT. The DNIS identifies to the CT system the application (i.e.. FoD) the caller dialed. D Channel An ISDN interface that is used to carry control signals and customer call data in a packet switched mode. Distributed computing The process by which data and applications are distributed to multi-user computers, workstations and PCs within a network rather than maintained on a central computer. A superset of client/server computing. DID Direct inward dialing is a capability that allows one to dial inside a company directly without going through the attendant. Used to be an exclusive feature of Centrex, but is now provided by almost all PBXs. One must connect via specially configured DID lines from the CO. Domain A level in the Internet administration system which assigns a name to the numerical address of a host computer. For example, the Internet Protocol address 204.191.36.242 is equivalent to the domain name ctsnet.com (the .com suffix indicates a commercial organization; other suffixes include .ca for Canada, .org, .edu, and so on). Duplex Two-way, real-time communication capability. As in a telephone but not a two way radio (called simplex). DSVD Digital Simultaneous Voice and Data. A new Modem card transmission technology. The European equivalent of the T-1 standard. E-1 has a higher throughput capacity than T-1. There are Digital Service Units (DSUs) available from companies such as Gandalf and AT&T Paradyne which can easily bridge the two circuits. Electronic Mail/E-mail An application that allows a user to send or receive text messages to or from any other user with an Internet address, commonly termed an E-mail address. Fiber Distributed Data Interface. An ANSI standard for a 100Mbps token-passing ring based on fiber optic transmission media. Firewall A gateway (software) between two networks that buffers and screens all information that passes between such networks. FLOPS A measure of processor performance based on floating point operations per second. Frame Generally a group of data bits in a specific format, with a flag at the beginning and end of the frame. A logical transmission unit which contains its own flow control information for addressing and error checking. Also, refers to a complete cycle of events in time division multiplexing. The frame usually includes a sequence of time slots for the various sub channels, as well as extra bits for control and calibration. FTP File Transfer Protocol. A protocol that allows file transmission over the Internet between two computers. The increase in signalling power that occurs as the signal is boosted by an electronic device. Measured in decibels (dB). Gopher An Internet tool allowing the user to browse for documents through menus on a computer running gopher server software. A Web site’s introductory information page. Hookswitch The place on the telephone where you lay your hand set or in the case of a portable telephone (not a cell phone) the on-off talk switch or button. Host A computer with direct access to the Internet. In a LAN, can be referred to as a host server. Contains Web server software and Web pages. HTML Hypertext Markup Language used to produce Web pages. It is a method of presenting information where selected words can be expanded to provide other information about or related to the word. An open, global network of interconnected private, commercial, educational and governmental computer networks which utilize a common communications protocol, TCP/IP. Intranet A closed, and sometimes widely dispersed network or wide area network (WAN) of interconnected computer networks and servers which use the Internet and its protocol, TCP/IP to communicate. ISDN Integrated Services Digital Network combines voice and digital network services through a single medium, making it possible to offer digital data services as well as voice connections. ISDN comes in two interfaces, Basic Rate Interface (BRI) and Primary Rate Interface (PRI). In ISDN 23B+D the one D channel is out of band signaling. In T-1, signaling is handled in-band using robbed bit signalling. Increasingly, 23B+D is the preferred way of getting T-1 service since out of band signaling is richer (delivers more information like ANI and DNIS) and is more reliable than in-band signaling on the older T-1. ISP Internet Service Provider. An organization that provides Internet access, connections and gateway services. IVR Interactive Voice Response. A CT caller-to-database application interface that allows a caller to access target information using a TouchTone(tm) phone. Callers can also leave information into a repository for processing, retrieve documents from a Web server or Fax-on-demand system for example. A programming language derived from C, which is used to create mobile agents. Mobile agents can be in the form of applets which simulate a client/server architecture over the WWW, as opposed to current browser/Web-server interactivity which is RPC based. Mobile agents like JAVA and M0 can free up host server resources by moving computations and application processing to the client, leaving the host to serve up files, data and other mobile agents. Mobile agents differ from CGI in that CGI is a server-based process script, and responds to calls made to it by the browser (or terminal). API calls from the browser are still RPC-based, although they use fewer system resources than CGI. CGI can be scripted in Perl or Visual Basic. They can be compiled (faster) or non-compiled. Java Rapid Application Development environments include Symantec Cafe and Microsoft Visual J++. Kilobits per second. A measure of digital information transmission rates. One kilobit equals one thousand bits of information. Local Area Network. A data communications network designed to interconnect personal computers, workstations, mini computers, file servers and other communications and computing devices with a localized environment. Mega bits per second. One thousand times kbps. MIPS Million instructions processed per second is a measure of processor compute power. See FLOPS. Also a registered tradename of a RISC processor manufacturer. MAPI Mail Application Programming Interface. A Microsoft technology standard for e-mail API. Modem MOdulate/DEModulate A piece of equipment that connects a computer to an analog communications transmission line, typically a plain old telephone line (POTS). The modem translates digital information by manipulating an analogue carrier (sine) wave from the POTS and changes that carrier signal in concert with the data it is sending. See Baud. A 28,800 bit per second modem is actually a 2400 baud modem with advanced coding such that 12 bits are impressed on each baud. Mean Opinion Scale Or MOS, is a rating system for sound quality over a transmission medium. Usually in reference to telephone or radio communications. The metric is scaled betwenn 0 and 5, with 4.5+ being the widely accepted commercially viable rating over the PSTN. Mosaic The first of three publicly available, commercial Web browsers. Multiplex A data routing and branching capability between multiple sources and recipients communicating amongst each other in real time. Multiplexer Combines multiple signals for simultaneous transmission. MVIP Multi-Vendor Integration Protocol. An open architecture for CT development. A collection of distributed computers which share data and information through interconnected lines of communication. Part of Microsoft’s Windows Open Services Architecture (WOSA) which describes a strategic interface for accessing data in a heterogeneous environment of relational and non-relational database management systems. Based on the Call-Level Interface (CLI) specification of the SQL Access Group (SAG), ODBC provides a vendor-neutral method of accessing data from a variety of data repositories. OSI Open Systems Interconnect reference model developed by ISO. It is used to describe the flow of data between the physical connection to the network and the end-user application. This is the best known and most widely used to describe networking environments. The 7 layers of the OSI Reference Model include: Application, Presentation, Session, Transport, Network, Data Link, and Physical. Between two computers that are interacting, there exists a like-layer, virtual communication path. Pulse Amplitude Modulation is a process which represents a continuous analog signal with a series of discrete analog samples. This is the basis of PCM and T-1. PBX Private branch exchange is analogous to the Telco's CO, but is owned and operated by someone other than the Telco. Provides the same service as CO but on a smaller scale and for a specific organization. PCM Pulse Code Modulation is the most common method of encoding (quantizing) an analog voice signal into a digital (binary) bit stream. POPs Points-of-Presence. An interlinked group of modems, routers and other computer equipment, located in a particular city or metropolitan area, that allows a nearby subscriber to access the Internet through a local telephone call or using a short distance permanent data circuit. Perl A language used for writing scripts that pass a CGI request from the Web server to run a gateway program. Predictive Dialler A system that intelligently makes and queues up calls based on the response and processing time required by a tele-operator to manage a script or questionnaire. It increases efficiency by dialling phone numbers at a certain rate and filling the pipe so as to keep call agents fed with live connections. Primary Rate The ISDN equivalent of a T-1 circuit. Contains 23 bearer channels Interface and one data channel in North America. Commonly referred to as 23B+D. This is enterprise level ISDN and highly desirable for CT applications. Protocol A formal description of message formats and the rules two or more machines must follow in order to exchange such messages. PSTN Is the public switched telephone network and refers to the local Telco and its network. PVC Permanent Virtual Connections are established between DSUs for duplexed data transmission. Can be associated with MODEM, Frame Relay, X.25, ISDN, T-1/E-1, T-3, OC-48, VSAT, ATM and other networks. A database that is organized and accessed according to relationships between data items. RISC Reduced instruction set computer based on VLSI (very large scale integration) where a faster processor clock cycle is implemented with smaller instructions to increase performance. Robbed Bit Signalling Typically uses the A & B bits which are sent on each side of the T-1 termination, and are buried in the voice data of each voice channel in the T-1 circuit. Hence the term as the bits are stolen from the voice data. Since the bits are stolen so infrequently voice quality is not overly compromised, but the available signaling combinations are limited to ringing, hang up, wink and pulse digit dialing. Router A device that receives and transmits data packets between segments in a network or different networks. RPC Remote Procedure Call is a command that is made from a station to another station to perform a transaction or computation within specifications and where the results are returned to the station making the call. Often confused with client/server. Software that allows a computer to offer a service to another computer but in the client/server world not an application computation or RPC service. Other computers contact the server program by means of matching client software. In addition, such term means the computer in which server software runs. SLIP/PPP Serial Link Internet Protocol/ Point-to-Point Protocol. The standardized description of a software program used to transmit data on asynchronous lines. SQL Pronounced Ess-Cue-El, not sequel, and due to evolution, the letters no longer mean anything, although confusion exists. In the mid 1970s, IBM Research Laboratory developed a language to implement the relational database management system model. The prototype language was called SEQUEL for Structured English Query Language and was the application programming interface to their embryonic relational database called System R. In 1977, a new design prototype emerged which was called SEQUEL/2; but, the name was later changed to SQL. This is the source of the common belief that SQL is an acronym for Structured Query Language and is pronounced sequel. The first company to market SQL relational database management systems was Relational Software, now known as Oracle Corporation. SQL is the accepted standard for data definition, data manipulation, data management, access protection, and transaction control of relational databases. It uses tables indexes, keys, rows, and columns to identify storage locations. Many types of applications use SQL statements to access data. Examples include ad hoc query facilities, decision support applications, report generation utilities, and online transaction processing systems such as relational Web environments. A digital transmission link with a capacity of 1.544 Mbps. Can normally handle 24 voice conversations each digitized at 64kbps. Typically used for connections of networks across remote distances (Wide Area Networks or WAN). Ideal for Internet connectivity, though not as desirable for CT as PRI ISDN. TAPI Telephony Aplication Programming Interface. A Microsoft and Intel API technology standard. TCP/IP Transmission Control Protocol/Internet Protocol. A compilation of network and transport level protocols that allow computers with different architectures and operating system software to communicate with other computers on the Internet. The IP transmits the data packets from the sender to the recipient in the shortest time possible. The TCP manages the flow and ensures the data is correct. Telnet A tool used to log into other computers connected to the Internet. It is typically used to access public servers, such as library, university and other databases. TSAPI Telephony Systems API. A Novell and AT&T technology standard. World Wide Web. A network of computer servers that uses a special communications protocol to link different servers throughout the Internet, and permits communication of graphics, video and sound. Web Sites or Web Pages A site located on the Web, written in HTML. See Home Page above. Web Server The computer system that runs Web software, used to create custom Web Sites, Web Pages and Home Pages. Also, the Web software itself. Windows NT A 32-bit, true preemptive multitasking and multi threading operating system for RISC and CISC-based servers, PCs and workstations. Originally co-developed with IBM and called OS/2, Windows NT supports POSIX I and II APIs, DOS and 16 bit Windows, as well as 32-bit Windows 95 applications. The operating system consists of the executive, the hardware abstraction layer, the Kernel, and the API layer which support the various applications. Windows NT supports C2-level security which allows multiple DOS, Win16 and Win32 sessions each within their own specially created virtual machine. Crash of one application occurs only within its virtual machine and does not affect other applications running or the data they contain. Windows NT runs on Digital Alpha AXP RISC CPUs, MIPS R CPUs, PowerPC and Intel CPUs. Windows NT is reported to run best on AXP and MIPS CPUs and Intel Pentium Pro CPUs.
An activity used by a transmitting fax machine which can send data faster than the recipient can process it. To give time for the recipient to catch up, the transmitter pads or zerofills the outbound transmission.
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