I

I-hold
    Visual flash indications that identify held calls from other calls.

I-Series recommendations
    ITU-TS (formerly the CCITT) recommendations on B-ISDN, ISDN and aspects of ATM.

I-use
    A visual indication that identifies currently busy lines.

I/O
    See input/output.

I/O channel
    See input/output channel.

IAB
    See Internet Activities Board (IAB)

IABS
    See Integrated Access Billing System (IABS)

IBDN
    See Integrated Building Distribution Network (IBDN)

IMCS
    See IBM Cabling System (IBMCS)

IBS
    See International Business Service

IC
    See:  Interconnect (IC), InterLATA Carrier (IC), Interexchange Carrier (IC, IEC, and IXC), or Integrated Circuit (IC).

ICB
    See Individual Case Basis (ICB)

ICECAN
    The submarine cable between Iceland and Canada.

ICMP
    See Internet control message protocol (ICMP)

ICR
    See Intelligent Character Recognition (ICR)

ICSI
    See Building Industries Consulting Service International.

Building Industries Consulting Service International
    A non-profit professional association for those engaged in voice or data cable plant design and installation. Administers the Registered Communications Distribution Designer (RCDD) and local area network (LAN) Specialist certifications and provides related training.

IDA
    See Integrated Digital Access (IDA)

IDAPI
    See Integrated Database Application Programming Interface (IDAPI)

IDD
    See International Direct Dialing (IDD)

IDF
See Intermediate Distribution Frame (IDF)

Idle Code
    A repetitive pattern to identify an idle channel (typically, 0111 1111).

IDN
    See Integrated Digital Network (IDN)

IEC
    See InterExchange Carrier (IC, IEC, and IXC)

IEC miles
    See InterExchange Carrier (long-distance) miles

IEE
    Institute of Electrical Engineers (UK)

IEEE
    See Institute Of Electrical and Electronic Engineers (IEEE)

IEEE 802
    A committee of the Institute of Electrical and Electronic Engineers (IEEE) responsible for setting standards for local area networks (LANs).

IEEE 802.1
    The Institute of Electrical and Electronic Engineers (IEEE) committee that defines network management and bridging standards.

IEEE 802.11
    The Institute of Electrical and Electronic Engineers (IEEE) committee developing a proposed standard for line-of-sight, wireless local area networks.

IEEE 802.2
    The Institute of Electrical and Electronic Engineers (IEEE) standard for logical link control which defines a specific format for data and interfaces to a series of IEEE-specified physical layers.

IEEE 802.3
    The Institute of Electrical and Electronic Engineers (IEEE) committee that defines the standards for 10Mbps carrier sense multiple access with collision detection (CSMA/CD) Ethernet local area networks. IEEE 802.3 physical layer specifications include 10BASE5, 10BASE2, 1BASE5, and 10BASE-T.

IEEE 802.4
    The Institute of Electrical and Electronic Engineers (IEEE) standard governing the use of the token-passing, bus-based, media-access method.

IEEE 802.5
    The Institute of Electrical and Electronic Engineers (IEEE) committee that defines the standards for 4Mbps and 16Mbps Token Ring Access Method local area networks and physical layer specifications.

IEEE 802.6
    The standard that defines Mans, an SMDS-based, short packet ATM transmission.

IEEE 802.6/DQDB
    The principal architecture for accessing metropolitan area networks. This distributed queue dual bus (DQDB) specification meets the Institute of Electrical and Electronic Engineers (IEEE) criteria for its stated purpose, and conforms to the open systems interconnection (OSI) reference model. The IEEE 802.6/DQDB specification works in conjunction with any synchronous transmission interface, including DS3, Consultative Committee on International Telephone and Telegraph (CCITT) G.703, and synchronous optical network (SONET) protocols.

IEEE 802.X
    The Institute of Electrical and Electronic Engineers (IEEE) committees, under the charter of American National Standards Institute (ANSI), that define and propose standards for the interconnection of local area network equipment, dealing with the physical and data link layers as defined by the open system interconnection (OSI) reference model.

IESG
    See Internet Engineering Steering Group (IESG)

Internet Engineering Steering Group (IESG)
    A US committee consisting of the IETF chairperson and the six area managers. The IESG coordinates activities among the IETF working groups.

IETF
    See Internet Engineering Task Force (IETF)

Internet Engineering Task Force (IETF)
    The standards and specifications review board for the Internet.

IFRB
    See International Frequency Registration Board (IFRB)

International Frequency Registration Board (IFRB)
    An organization whose major task is to assign radio frequencies to stations, and to determine that radio frequencies assigned by various countries do not cause harmful interference to stations in other countries.

IFRS
    See inter-carrier frame relay service (IFRS)

Inter-carrier Frame Relay Service (IFRS)
    The frame relay services provided across service multiple, public frame relay networks.

IGP
    See Interior Gateway Protocol (IGP)

Interior Gateway Protocol (IGP)
    The term applied to any protocol used to propagate network reachability and routing information within an autonomous system. There is no single standard IGP, but RIP is one of the most common.

Imaging Server
    A server designed to access information from other servers, scanners, and optical libraries on a network.

Impedance
    The resistance, in ohms, to an AC signal in a transmission medium.

IMS
    See Information Management System (IMS)

Information Management System (IMS)
    A hierarchical-database-oriented transaction processing software used by the Bellcore Service Management System (SMS)/800 system.

IMT
    See inter-machine trunk (IMT)

Inter-Machine Trunk (IMT)
    A high capacity connection between two automatic switches, such as DMS-250 to DMS-250.

IMTC
    See International Multimedia Teleconferencing Consortium, Inc. (IMTC)

International Multimedia Teleconferencing Consortium, Inc. (IMTC)
    A non-profit corporation dedicated to promoting the ongoing development and adoption of international standards for multipoint audiographics and video teleconferencing (ITU T.120 & H.320 suites).

IMTS
    international message telephone service
See international MTS

international MTS
    International switched long-distance service.

IMV/VS
    See Information Management System/Virtual Storage (IMV/VS)

Information Management System/Virtual Storage (IMV/VS)
    A database management software system that provides communications monitor functions and virtual storage.

IN
    See Intelligent Network (IN)

Intelligent Network (IN)
    A sophisticated network capable of recognizing the profile (authorization, chosen services) of its users or subscribers. Carriers offering advanced services will increasingly offer IN services, particularly as the boundary between fixed and mobile networks becomes blurred.

in-band signaling
    1) A type of signaling using an alternating current (AC) signal (usually 2600 Hz) within the normal voice band. This signal can be transmitted end to end on a long voice circuit without intermediate signaling equipment. Since the signaling is audible, the signaling equipment must be arranged for tone-on-when-idle operation. 2) A method of sending signals over the same channel bandwidth as service being provided to a customer. Contrast with out-of-band signalling.

inactive ANI report
    A nonproductive phone report.

inband
    See in-band signaling

in-band signaling
    1) A type of signaling using an alternating current (AC) signal (usually 2600 Hz) within the normal voice band. This signal can be transmitted end to end on a long voice circuit without intermediate signaling equipment. Since the signaling is audible, the signaling equipment must be arranged for tone-on-when-idle operation. 2) A method of sending signals over the same channel bandwidth as service being provided to a customer. Contrast with out-of-band signalling.

inclination
    The angle between the orbit plane and the earth's equatorial plane, measured counter-clockwise. A zero inclination orbit would mean the satellite is orbiting directly over the equator, an inclination of 90 degrees is a perfectly polar orbit.

incoming call identification
    A feature that provides an attendant console with visual identification of the type of service or trunk group of incoming calls. See incoming call indicator

incoming call indicator
    A device that provides an attendant console with a visual or audible identification of the type of service or trunk group of the incoming calls.

incoming call to tie line connection
    The ability of a system to connect an incoming network exchange call to a remote private branch exchange (PBX) station through a tie line.

incremental usage charges
    See measured service

measured service
    The mechanized interface to the Service Management System (SMS)/800. Direct computer-to-computer interaction software between an interexchange carrier (IEC) computer systems and the SMS/800. This is in contrast with manual 'online' or 'batch' file processing modes. Synonym: mechanized generic interface See Service Management System and responsible organization.
Service Management System (SMS) responsible organization (RO and resporg)

IND$FILE
    The IBM file transfer protocol.

Indefeasible Right of Use (IRU)
    An unconditional right to use a facility, such as a satellite transponder or a fiber pair in a trans-oceanic, fiber-optic cable. The IRU holder enjoys most of the perks of ownership, except the right to control the operation of the facility in which the circuit lies.

INDEO
    Intel's compression/decompression algorithm for scalable software playback video. Intel licenses Indeo technology to companies such as Microsoft who integrate it into products such as Video For Windows. Indeo technology can record 8, 16 or 24 bit sequences and stores the sequence as 24 bit for scalability on higher power PCs.

independent telephone company
    A non-Bell system local exchange carrier (LEC).

individual case basis (ICB)
    Nonstandard situations where special arrangements are required to satisfy unusual requirements. General tariffs do not apply.

Industry Standard Architecture (ISA)
    IBM peripheral-expansion architecture (bus) or PC AT Architecture developed for PC, XT, and AT computers.

info digits
    See information digits

Info Pro(TM)
    A division of Bell Canada which acts as the company's consulting agent by marketing Bell expertise throughout Canada.

INFOPAC
    A packaged software for an on-line reporting system. Various facilities and equipment (F&E) system reports may be viewed on-line instead of printing hard copies. If the users need hard copies, they can print all, or part, of the reports on their own printer. INFOPAC log-on IDs, passwords, and report selections are setup by Security Administration.

information bit
    A bit generated by the data source representing user data to be delivered to the data sink. Compare with overhead bit.

information content provider
    A business that supplies information or programming services such as news, weather, business reports, and entertainment.

information digits
    The two digit codes that precede the 7-or-10 digit destination number and inform exchange carriers and interexchange carriers (IECs) about the type of line that originated the call, any special characteristics of the billing number, or certain service classes. These codes, plus the destination number, are part of the signalling protocol of equal access offices. These codes are defined by Bellcore. Examples are: 00 - plain old telephone service (POTS), 01 - multiparty, 02 - ANI failure, 06 - hotel/motel, 07 - special operator handling, 20 - AIOD, 24 - 800, 27 - coin, 30 - unassigned DN, 31- trouble/busy, 32 - recent change or disconnect, 34 - telco operator, 52 - outward wide area telecommunications service (WATS), 61- cellular 1, 62 - cellular 2, 63 - roaming, 70 - private pay phone, 93 - private virtual network.

information highway
    A network, consisting of many connected networks, which has the capacity to carry high-speed, broadband services, including interactive and voice, data, image and video communication. The network will allow customers to reach offices, homes, schools, hospitals and a variety of other institutions.

information management system (IMS)
    A hierarchical-database-oriented transaction processing software used by the Bellcore Service Management System (SMS)/800 system.

information management system/virtual storage (IMV/VS)
    A database management software system that provides communications monitor functions and virtual storage.

information provider
    See information content provider

information content provider
    A business that supplies information or programming services such as news, weather, business reports, and entertainment.

information superhighway
    A Clinton/Gore administration plan to deregulate communications services beginning with 1994 legislation. It integrates concepts from Internet, community antenna television (CATV), telephone, business, entertainment, information providers, education, and other sources. The potential impact to businesses, schools, homes, and society as a whole are significant. CATV will be allowed to provide telephone and videoconferencing services. Telephone companies will be allowed to provide movies and information services.

information systems network
    A network of all the communications approaches used within an organization.

Information Systems Solutions Corp. (ISSC)
    An IBM subsidiary computer center outsourcing company.

infotainment
    The integration of information, education and entertainment services.

infrared
    The part of the electromagnetic spectrum with wavelengths between 0.75 and 1000 microns. Infrared radiation is employed for fiber-optical transmission, and short-haul, through-the-air data transmission.

inheritance
    The transfer of object features, including attributes and operations, from a "class" that defines the common features of similar objects.

initial program load (IPL)
    The initial loading of generic and/or configuration software into a private branch exchange (PBX) or other telephone system.

initialization string
    A series of commands sent by your terminal program to configure your modem, usually when the program is started or when auto-dialing pre-defined communications service telephone numbers.

INMARSAT
    See International Maritime Satellite Organization

International Maritime Satellite Organization
    Oversees commercial sea-to-land satellite communications. Parallel body to INTELSAT.

innerduct
    Tubing placed in a duct space, trench, or pipeline. Cable may be placed in the innerduct when the innerduct is installed, or at a subsequent time.

INPA
    See interchangeable numbering plan area (INPA)

interchangeable numbering plan area (INPA)
    A long distance dialing plan in which customers must dial the area code when placing a long distance call -- even for calls placed within their own area code.

input/output (I/O)
    The process for transmitting data to and from a computer processor and its peripherals.

input/output channel
    A device that allows independent communications between the memory exchange and the input/output (I/O) exchange. The input/output channel controls all peripheral devices and performs all validity checking on information transfers.

inside wiring
    The wiring within a customer's premises used for internal communications, or to connect the customer premises equipment (CPE) to the network interface.

installable file system
    A file system that can be installed in place of the usual file allocation table file system, such as the high-performance file system.

installation
    Service initiation of a circuit, data access line (DAL), or port connection.

Institute Of Electrical and Electronic Engineers (IEEE)
    The Institute of Electrical and Electronic Engineers is a publishing and standards-making body responsible for many communications standards, including the 802.X series of local area network (LAN) specifications.

integral bridging
    A technique that combines different local area network (LAN) media and topologies. Integral bridging requires the installation of additional network interface cards in the server.

integrated access
    The use of a single connection or circuit to access multiple telecommunications services, such as private lines, switched services, or frame relays.

integrated access billing system (IABS)
    A computerized application system used by local exchange carriers (LECs) to bill access services.

integrated adapter
    The part of a processing unit that furnishes the direct link of a specific type of device and uses neither a control unit nor the standard input/output (I/O) interface.

Integrated Building Distribution Network (IBDN)
    A universal cable system that provides voice/data within a building (e.g., key, PBX and Centerx telephone systems can be connected to one cabling system).

integrated circuit (IC)
    An electronic device that contains hundreds or thousands of previously distinct components on a small plastic chip.

Integrated Database Application Programming Interface (IDAPI)
    A standard from Borland and others providing a standard interface to a wide range of databases. It is supposed to be a superset of ODBC.

Integrated Digital Access (IDA)
    The means of providing digital access for subscribers to the BT ISDN service. Two versions: single line IDA and multi-line IDA are available.

integrated digital network (IDN)
    A switched network providing voice or voice-simulated services through digital transmission and time-division technology.

integrated services digital network (ISDN)
    1) A set of standards for transmission of simultaneous voice, data and video information over fewer channels than would otherwise be needed, through the use of out-of-band signalling. The most common ISDN system provides one data and two voice circuits over a traditional copper wire pair, but can represent as many as 30 channels. Broadband ISDN extends the ISDN capabilities to services in the Gigabit range. 2) A digital network that permits the switched interconnection of voice, data, and video transmissions requiring differing capacities over common facilities.

integrated voice/data terminal (IVDT)
    A term relating to a variety of combined voice and data communications devices. Configurations range from computer terminals with telephones, telephones with built-in display screens for interface with computers, and cable-connected systems consisting of a cluster controller and multiple handset/screen keyboard stations. Some IVDTs are private branch exchange (PBX)-proprietary devices, while others are independent standalone devices. IVDTs generally consist of a dial-done multifrequency (DTMF) telephone handset or speakerphone, an integral or a detachable cathode ray tube (CRT), a keyboard, and a microprocessor. Options may include printer, an liquid crystal display (LCD) or plasma display, a numeric keypad, a modem, a mass storage device, communications software, data base or mainframe access, and teletypewriter (TTY) interface capabilities. Voice and data signals can be transmitted over two separate lines; multiplexed over a single line; or simultaneously transmitted over one line. Applications include voice communications, data processing, and various types of communications relating to payroll and financial planning, sales forecasting, inventory management, document handling, and image and graphic information transfer.

integrity
    A systems capability to prevent damage or unauthorized access to information.

Intelligent Character Recognition (ICR)
    Software similar to OCR, but it learns to recognize different fonts and character styles, so is more efficient. Useful to make paper documents accessible via groupware.

intelligent gateways
    Devices that exchange information to determine the optimal means of routing network traffic. Intelligent gateways consider such factors as congestion, priority, performance, throughput, delay, error rate, security, and cost.

Intelligent Network (IN)
    A sophisticated network capable of recognizing the profile (authorization, chosen services) of its users or subscribers. Carriers offering advanced services will increasingly offer IN services, particularly as the boundary between fixed and mobile networks becomes blurred.

intelligent switch
    A switch interface with a front-end processor and/or a concentrator that routes messages to the various network end points.

intelligent terminal
    See intelligent workstation

intelligent workstation
    A terminal that can be programmed. Intelligent workstations provide the user with independent processing power and applications support.

INTELSAT
    See International Telecommunications Satellite Organization (INTELSAT)

inter-carrier frame relay service (IFRS)
    The frame relay services provided across service multiple, public frame relay networks.

inter-machine trunk (IMT)
    A high capacity connection between two automatic switches, such as DMS-250 to DMS-250.

Inter-Process Communications (IPC)
    Communications between several programs based on one computer or across a number of machines. Alternatively, communication across a network between different processes of the same program between different computers running parts of a single program, or between two programs working together. The most common approaches to IPC in networking circles are probably Application Programming Interfaces such as APPC and NetBios.

interactive
    The ability to interact or be in conversational mode with a computer.

interactive television
    The ability to communicate with a cable company via a television and thus select programs, participate in games, or purchase goods and services.

interactive voice response (IVR)
    The ability to interact or be in conversational mode with a computer. Interactive voice response uses remote touchtone telephones and a digitized synthesized voice to "read" the screen to the distant caller.

intercept
    The stopping a telephone call directed to an improper telephone number, and redirect that call to an operator or a recording.

intercept treatment
    The process of routing calls that can't be completed to either a recording, an audible signal, or an attendant.

intercept-type information digits
    The two digit codes that define the reasons calls were intercepted. Examples are: 30 - unassigned dialed number (DN), 31 - manual assignment: trouble or busy, 32 - recently changed.

interchangeable numbering plan area (INPA)
    A long distance dialing plan in which customers must dial the area code when placing a long distance call -- even for calls placed within their own area code.

intercom
    An internal communications system allowing a user to dial another in-house telephone or disconnected DN.

interconnect (IC)
    1) The arrangement that permits the connection of a customer's telecommunications equipment to a communications common carrier network. 2) The industry name for manufacturers, excluding the Bell system, that provide telephone equipment for customer premises. 3) The provision of customer premises equipment (CPE).

interexchange (IX)
    Communications between two local access transport areas (LATAs).

interexchange carrier (IC, IEC, and IXC)
    1) A company providing long-distance telephone service between local exchange carriers (LECs) and local access transport areas (LATAs). IEC is the preferred acronym. 2) Interexchange circuit; interexchange channel. 3) Revenues resulting from the provision of interexchange circuits, excluding local access.

interexchange carrier (long-distance) miles
    The coordinates of location A and location B are used to calculate mileage-dependent line charges on a price quote.

interexchange channel (IXT)
    A communications path between two or more telephone exchanges.

interexchange circuit
    A circuit that connects points of presence (POPs). Dedicated interexchange circuits have a recurring charge rate element.

interexchange mileage
    The airline mileage between two cities. Synonym: long-haul mileage

interexchange plant (IP)
    The facilities between the subscriber switching center and another switching center.

interexchange voice grade channel (IXVG channel)
    An analogue-dedicated channel between two exchanges primarily for the use of business customers.

interface
    The junction or point of interconnection between two systems or equipments having different characteristics. An interface includes the types and functions of the interfacing circuits, such as impedance and signal levels and forms, and the nature and coding of the information exchanged.

interference
    Any unwanted noise or crosstalk on a communications circuit that reduces the intelligibility of the desired signal or speech.

interflow
    The ability to initiate a link to a second automatic call distributor (ACD) and overflow a call from one ACD to the other.

interframe compression
    A form of video compression that compresses full-motion video by analyzing each frame of a video, determining which frames duplicate previous frames, and deleting the duplicates.

Interior Gateway Protocol (IGP)
    The term applied to any protocol used to propagate network reachability and routing information within an autonomous system. There is no single standard IGP, but RIP is one of the most common.

interLATA
    The services, revenues and functions that relate to telecommunications originating in one local access transport area (LATA) and terminating in another LATA or outside of a LATA. The 1982 Modification of Final Judgement (MFJ) requires the local exchange carrier (LEC) to use an interexchange carrier (IEC) for interLATA services.

interLATA carrier (IC)
    Any carrier that provides telecommunications services between a point in a local access transport area (LATA) and a point in another LATA, or outside a LATA.

interleave
    The process of sending blocks of data alternately to two or more stations on a multipoint circuit.

intermediate crossconnect
    An element in the Electronic Industries Association (EIA) 568 Commercial Building Wiring standard. It consists of the active, passive, and support components that connect the interbuilding cabling and the intrabuilding cabling for a building.

intermediate distribution frame (IDF)
    A distribution frame that provides connections between the main distribution frame (MDF) and specific telephone wiring.

intermediate station number
    A call processing station between the calling and called stations. The intermediate station sends information to the calling and called stations concerning the call process.

intermediate system (IS)
    An open system interconnection (OSI) term for a system that originates and terminates traffic, and that also forwards traffic to other systems.

internal CD-ROM drive
    A CD-ROM drive that is installed inside the computer.

internal clocking
    The situation when the Cascade switch provides the transmit and receive clocks to the user equipment.

internal modem
    A PC-mounted data transfer (communications) adapter. See external modem and rackmount modem.
external modem
rack-mount modem

International Business Service
    A public document switching service (PDSS) provided internationally.

international circuits
    The international portion of an international private line circuit that runs between two International Transmission Maintenance Centers (ITMCs); a U.S. based center and a center located in the foreign country. This transport may be by satellite or undersea cable. International circuits are usually further divided into two components, the US half and the foreign half. Accounting for these half circuits is based on a theoretical midpoint (TMP) along this circuit.

International Consultative Committee on Telephone and Telegraph
    An international organization that develops standards and defines interfaces for telecommunications. This organization is now known as the International Telecommunication Union (ITU).

international direct dialing (IDD)
    A system that enables subscribers to place international calls without operator assistance.

International Electrotechnica Commission (IEC)
    The electrical standardizing division of the International Standards Organization (ISO).

International Frequency Registration Board (IFRB)
    An organization whose major task is to assign radio frequencies to stations, and to determine that radio frequencies assigned by various countries to their radio stations do not cause harmful interference to stations in other countries.

International Maritime Satellite Organization
    Oversees commercial sea-to-land satellite communications. Parallel body to INTELSAT.

international MTS
    International switched long-distance service.

International Multimedia Teleconferencing Consortium, Inc. (IMTC)
    A non-profit corporation dedicated to promoting the ongoing development and adoption of international standards for multipoint audiographics and video teleconferencing (ITU T.120 & H.320 suites).

international number
    The number dialed following the international prefix.

international prefix
    The first part of an international telephone address, consisting of the country code and city code.

international record carrier (IRC)
    Carriers providing international telecommunications services, including voice, telex, and data communications.

International Standards Organization (ISO)
    An international agency responsible for developing international standards for information exchange. The U.S. representative to the ISO is the American National Standards Institute.

international subscriber dialing (ISD)
    See international direct dialing (IDD)

international switching center (ISC)
    An exchange that switches telephone traffic between different countries.

International Telecommunications Satellite Organization (INTELSAT)
    1) An international body owned by its member nations, including the U.S. and over 120 other countries. Coordinates international satellite communications. 2) A satellite operated by INTELSAT.

International Telecommunications Union (ITU)
    A specialized agency of the United Nations that sets technical standards for world communications to prevent destructive interference, and to develop basic operating arrangements under which member nations communicate.

international telephone address
    A code of 12 digits or less that specifies a unique address for any telephone in the world (i.e., a country or regional identity code of 1, 2, or 3 digits; a 3-digit numbering plan area code; a 2- or 3-digit central office code; plus a 4-digit station number).

international test and maintenance centers (ITMC)
    The point of demarcation for international circuits. Although it may be physically different from the undersea cable head or the satellite earth-station, it is often thought of as the end of domestic traffic and the beginning of international traffic.

Internet
    A large international communications network that connects government agencies, technical universities, commercial customers and private individuals. It grew out of the original ARPANET and uses Internet protocol (IP) to link the various physical networks into a single logical network. It is growing at 20% per month. Internet is a prototype of some services that will be on the information superhighway. See information superhighway, transmission control protocol/Internet protocol (TCP/IP), management information base, Usenet, World Wide Web, Gopher, and wide area information server.

Internet Activities Board (IAB)
    The technical body that sets policy and standards for TCP/IP and the connected Internet suite of protocols. Its task forces are the IETF and IRTF.

Internet address
    1) The 32-bit address assigned to Internet hosts using the transmission control protocol/Internet protocol (TCP/IP). 2) An IP address assigned in blocks of numbers to user organizations accessing the Internet by the US DoD's Network Information Center. Duplicate addresses can cause major headaches on the network, but the NIC trusts organizations to use individual addresses responsibly. Each address is an eight- bit number (0 to 255). There are three classes: A, B and C, depending on how many computers on the site are likely to be connected. The NIC is running out of Class B addresses, so work is in progress to extend the address format to allow expansion into the next century.

Internet control message protocol (ICMP)
    ICMP delivers error and control messages from hosts to message requestors. An ICMP test may determine whether a destination is reachable. An ICMP echo is also called a packet Internet groper (PING).

Internet Engineering Steering Group (IESG)
    A US committee consisting of the IETF chairperson and the six area managers. The IESG coordinates activities among the IETF working groups.

Internet Engineering Task Force (IETF)
    The standards and specifications review board for the Internet.

Internet packet exchange (IPX)
    A Novell NetWare packet-forwarding protocol similar to the Internet protocol.

Internet protocol (IP)
    The Internet protocol that defines the unit of information passed between systems providing a basis packet delivery service within the transmission control protocol/Internet protocol (TCP/IP). IP is used in gateways to link networks at an open systems interconnection (OSI) network Level 3 and above. IP is a standard that describes how packets of data are transported across the Internet and recognized as an incoming message. See transmission control protocol.
transmission control protocol (TCP)

Internet protocol address
    An Internet protocol (IP) address that uniquely identifies a node or host connection to an IP network. System administrators or network designers assign IP addresses to nodes. IP addresses are configured by software. An IP address is a 32 bit binary number usually represented as four fields each representing eight bit numbers in the range 0 to 255 (sometimes called octets) separated by decimal points. An IP address consists of two parts, one identifying the network and one identifying the node. The class of the address determines which part belongs to the network address and which part belongs to the node address. There are 5 classes A - E. IP is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address or IP number.

Internet relay chat (IRC)
    A software tool that makes it possible to hold real-time keyboard conversations on-line.

Internet Research Task Force (IRTF)
    A technical group working or problems related to TCP/IP and the connected Internet, The IRTF is divided into a set of research groups. The IRTF chairperson is a member of the IAB.

internetwork
    A network that incorporates multiple sub-networks.

internetwork protocol (IP)
    An International Standards Organization (ISO) standard defining a portion of the Layer 3 network open system interconnection (OSI) model responsible for routing and delivery. IP provides for transmitting blocks of data between hosts identified by fixed-length addresses.

internetworking
    The connecting of two or more networks together by bridges, routers, and gateways.

interoffice channel
    The point of presence (POP)-to POP portion of an interexchange circuit.

interoffice trunk
    A trunk circuit linking two local central offices (COs).

Interop
    A communications industry trade show.

interoperability
    1) The ability to exchange information and operate in multi-vendor, heterogeneous networking environments. 2) A state of complete compatibility among devices required to operate together with each other, with reference to a specified feature set or standard. This is an important consideration when mixing non-ITU-T codecs from different manufacturers and when mixing ITU-T codecs from different manufacturers which may support different capabilities. Remember that ITU-T codec systems revert to the highest common denominator for operation.

interprocess communications (IPC)
    A communications protocol that specifies how data is exchanged between applications or threads.

interrupt
    A break in the control of a program or system. Interrupts typically incorporates a mechanism to store the information needed for a return to the interrupted program.

interrupt request line (IRQ)
    The communications channel through which devices issue interrupts to the interrupt handler of a personal computer's (PC's) microprocessor. Different IRQs are assigned to different devices. This assignment pattern differs from PC to PC. Many local area network (LAN) adapter cards use an IRQ to get to the PC's microprocessor.

interrupt request signal
    A method by which input/output (I/O) peripherals request attention from a PC's central processing unit (CPU).

interruption
    A break in the continuity of a signal or of service.

interstate
    Any telecommunications channel, facility, or network that provides transmission between locations in two or more states. Interstate operation is regulated by the Federal Communications Commission (FCC).

interswitch trunk
    A direct connection between switches using a proprietary protocol.

intertoll trunk
    A trunk between toll switching offices in different exchanges used to route long distance calls.

intraflow
    The ability to select a fallback group of attendants to backup the primary attendant group in an automatic call distribution (ACD) system.

intraframe compression
    A form of video compression that compresses full-motion video on a frame-by-frame basis.

intraLAN traffic learning
    A smart or learning bridge that learns intraLAN traffic by identifying each device on a particular local area network (LAN). Some bridges accomplish this within several seconds, even for LANs with several hundred terminals.

intraLATA
    The services, revenues, and functions that relate to telecommunications originating and terminating within a single local access transport area (LATA). The 1982 Modification of Final Judgement (MFJ) allows local exchange carriers (LECs) to handle these calls without an interexchange carrier (IEC).

intranet
    An network internal to a company that offers similar features and services as the Internet. External users generally have no access to a company's Intranet.

intraoffice trunk
    A telephone path between two pieces of equipment within the same central office (CO).

intrastate
    Any connection within a single state. Intrastate connections are regulated by each state's public utility commission (PUC).

intrude
    See executive override

invalid bill code
    The calling number is restricted in billing, such as a collect only, or a no bill to an automatic number identification (ANI).

invalid credit card
    A calling card or commercial credit card that cannot be validated.

invalid IDDD
    A restricted international location is dialed.

inverse multiplexer
    A device that provides bandwidth-on-demand for video-conferencing, file transfers and high speed applications. Inverse multiplexers use multiple switched 56 kbps or 64 kbps connections to achieve whatever bandwidth the users application requires.

invoice
    A paper or electronic bill for products or services rendered.

invoicing
    The process or computer programs for calculating, producing, and distributing bills.

inward restriction
    Selection station lines are prevented from receiving incoming exchange network and common control switching arrangement (CCSA) calls. The lines are usually given intercept treatment.

IOC
    See interoffice channel

IOCOM
    The submarine cable between Malaysia and India.

IOD
    identified outward dialing

IOT
    See interoffice trunk

IP
    See interexchange plant (IP), Internet protocol (IP), internetwork protocol (IP)

IP address
    The 32-bit Internet protocol address assigned to a host. The IP address has a host component and a network component.

IPC
    See interprocess communications (IPC)

IPL
    See initial program load (IPL)

IPX
    See Internet packet exchange (IPX)

IPX/link
    A NetWare application to connect a personal computer (PC) Novell NetWare local area network (LAN) through a network interface device.

IRC
    See Internet relay chat (IRC), or international record carrier (IRC)

IRE Scale Units
    The Institute of Radio Engineers standard measure of NTSC video signal amplitudes for which 140 IRE scale units equals 1.00 volt peak-to-peak.

IRQ
    See interrupt request line (IRQ)

IRTF
    See Internet Research Task Force (IRTF)

IRU
    See indefeasible right of use (IRU)

IS
    See intermediate system (IS)

ISA
    See Industry Standard Architecture (ISA)

ISC
    See international switching center (ISC)

ISD
    See international subscriber dialing (ISD), or international direct dialing (IDD)

ISDN -- Integrated Services Digital Network.

1) A set of standards for transmission of simultaneous voice, data and video information over fewer channels than would otherwise be needed, through the use of out-of-band signaling. The most common ISDN system provides one data and two voice circuits over a traditional copper wire pair, but can represent as many as 30 channels. Broadband ISDN extends the ISDN capabilities to services in the Gigabit range. 2) A digital network that permits the switched interconnection of voice, data, and video transmissions requiring differing capacities over common facilities.

ISDN BRI Line

An ISDN Basic Rate Interface line that uses two B channels for user data, and one 16-kbps D channel for ISDN D-channel signaling. Both B channels can be switched, both channels can be nailed up, or one channel can be switched and the other nailed up. BRI stands for Basic Rate Interface. A line of this type can connect to standard voice service, Switched-56 data service, or Switched-64 data service.

ISDN D-Channel Signaling

A type of signaling in which a D channel handles WAN synchronization and signaling, and the B channels carry the user data. Another term for ISDN D-channel signaling is out-of-band signaling. T1 PRI, E1 PRI, and ISDN BRI lines use ISDN D-channel signaling.

ISDN Multirate

A network-based ISDN service which allows users network access equipment to dial network channels of bandwidth in increments of 64 kbit/s, up to 1536 kbit/s. Access to ISDN Multirate service is obtained over ISDN PRI lines.

ISDN PRI Line

An integrated services digital network (ISDN) circuit transmitting at T1, or DS-1, speed providing the equivalent of 24 voice-grade channels. The "D" channel is used for signaling, leaving 23 "B" channels for data and voice communications.  An ISDN Pulsed Rate Interface

ISO
    See International Standards Organization (ISO)

ISO 7776
    The high-level data link control procedures x.25.

ISO 8208
    X.25 packet level protocol for data terminal equipment (DTE).

ISO 9000
    The International Standards Organization (ISO) standard that defines quality systems of varying scope. The ISO 9000 is made up of the ISO 9000 through ISO 9004 specifications.

ISO reference model
    The internationally accepted framework of standards for intersystem communications. The standards regulate all aspects of information exchange between systems to guarantee communication across all manufacturer's systems. The open systems interconnection (OSI) standards consist of seven functional layers in data communications. From the innermost layer, the layers include: 1) the physical layer: Concerned with the mechanical and electrical means by which devices are physically connected and data is transmitted. 2) the data link layer: Concerned with moving data reliably across the physical data link. 3) the network layer: Concerned with establishing, maintaining, and terminating connections between systems, the switching and routing of information. 4) the transport layer: Concerned with end-to-end data integrity and quality of service. 5) the session layer: Concerned with setting up a session and terminating it, the coordination of interaction between end-application processes. 6) the presentation layer: Concerned with the character set and data code used, and the way data is displayed on a screen or printer. 7) the application layer: Concerned with the higher-level functions that provide support to the application or system activities.

isochronous
    A hybrid synchronous transmission timing scheme in which the modem clock depends on the terminal clock.

ISSC
    See Information Systems Solutions Corp. (ISSC)

ISVYVU9
    Recording format for uncompressed Indeo video using VidCap under Video For Windows.

ITMC
    See international test and maintenance centers (ITMC)

ITU
    See International Telecommunications Union (ITU)

ITU-R (formerly CCIR)
    An International Telecommunications Union (United Nations) international telecommunications standards-setting body, specializing in radio-spectrum usage.

ITU-T (formerly CCITT)
    An International Telecommunications Union (United Nations) international telecommunications standards-setting body specializing in telecommunications.

ITU-T-Compatible Codec
    A video codec which meets all the minimum requirements as set out in ITU-T Recommendations H.221, H.230, H.242, H.261 and H.320. In order to be compatible with the ITU-T Multipoint Control Unit (MCU), codecs also need to generate and receive commands as set out in H.231 and H.243. T.120 support is also desirable.

IVDT
    See integrated voice/data terminal (IVDT)

IVR
    See interactive voice response (IVR)

IX
    See interexchange (IX)

IXC
    See interexchange carrier (IC, IEC, and IXC)

IXC miles
    See interexchange carrier (long-distance) miles

IXT
    See interexchange channel (IXT)

IXVG channel
    See interexchange voice grade channel (IXVG channel)