Operations, Administration, and Maintenance

Operations, Administration, Maintenance, and Provisioning

Operate, Administer, Maintain, and Provision

Ordering and Billing Forum

1. In image processing, a sub-region of an image that is perceived as a single entity.
Note: An image can contain more than one object.
2. In facsimile systems, the image, the likeness of which is to be transmitted.
3. [A] Passive entity containing or receiving information. Access to an object implies access to the information it contains. [INFOSEC-99]
4.… (Read More →)

1. Pertaining to, or characteristic of, a computer program consisting of (a) many relatively small, simple programs (subroutines), and (b) one monitor program, the function of which is to coordinate the exchange of data among the subroutines.
Note: Subroutines designed under this concept may be stored in object libraries, and used by other computer programmers with similar functional requirements.
2.… (Read More →)

In a video display, distortion wherein the entirety of some object (or objects) that appeared in a previous frame (and that should no longer appear) remain in the current frame and in subsequent frames as a faded image or as an outline.

In a video display, distortion in which a fragment of an object that appeared in a previous frame (and should no longer appear) remains in the current and subsequent video frames.

1. Reassignment and re-use of a storage medium containing one or more objects after ensuring no residual data remains on the storage medium. [INFOSEC-99]
2. Reuse of a storage medium for a different object [CESG].
Note: [1] A vulnerability may exist if the medium contains residual data from a previous object. [2] This is now the accepted term, despite the… (Read More →)

In cryptography, pertaining to the state of a key that must no longer be used either to transmit information from the originator or to process received secure information. [After X9.17]

In encryption, the date and time when a key becomes obsolete. [After X9.17]

Abbreviation for optical carrier. The nomenclature for the line rate of the optical transmission signal. [T1.106-1988]

OpenCable Application Platform

Abbreviation for other common carrier.

For equipment, such as a circuit or a switch, the ratio of the actual time in use to the available time during a 1-hour period.
Note 1: Occupancy is usually expressed in percent.
Note 2: Occupancy may be plotted versus time of day. Synonym usage.

1. The width of a frequency band such that, below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage B/2 of the total mean power of a given emission. Unless otherwise specified by the CCIR for the appropriate class of emission, the value of B/2 should be taken as
0.… (Read More →)

A station in the maritime mobile service the emissions of which are used to initiate, modify or terminate functions of equipment directly associated with an oceanographic data station, including the station itself. [NTIA]

A station in the maritime mobile service located on a ship, buoy, or other sensor platform the emissions of which are used for transmission of oceanographic data. [NTIA]

Open Cable Home Network

An Operating Company Number (OCN) is a four place alphanumeric code that uniquely identifies providers of local telecommunications service. OCN assignments are required of all SPs in their submission of utilization and forecast data (FCC 00-104, ¶ 41 and Public Notice DA 00-1549). Relative to CO Code assignments, NECA assigned Company Codes may be used as OCNs.

The OCN of the highest related legal entity located within the state for which the SP is reporting data or requesting numbering resources. See also 47 CFR §52. 15 (f) (3) (ii).

Abbreviation for optical character reader, optical character recognition.

A byte of eight binary digits usually operated upon as an entity.

The configuration of a field composed of an integral number of octets.
Note: If the field is not divisible by eight, bits (usually zeros) are added to either the first octet (left justification) or the last octet (right justification).

Abbreviation for optical density.

See parity, parity check.

Synonym parity check.

United States Department of Homeland Security Office of Emergency Communications (OEC) - formerly NCS (see National Communications System). OEC is now called Cybersecurity and Infrastructure Security Agency (CISA); Emergency Communications Division (ECD).

Organization for Economic Co-operation and Development

Original Equpiment Manufacturer

Abbreviation for optical fiber, conductive.
Note: OFC is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain at least one electrically conductive, non-current-carrying component, such as a metallic strength member or vapor barrier, and which are not certified for use in plenum or riser applications. [After FAA]

Abbreviation for optical fiber, conductive, plenum.
Note: OFCP is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain at least one electrically conductive, non-current-carrying component such as a metallic strength member or vapor barrier, and which are certified for use in plenum applications. [After FAA]

Abbreviation for optical fiber, conductive, riser.
Note: OFCR is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain at least one electrically conductive, non-current-carrying component such as a metallic strength member or vapor barrier, and which are certified for use in riser applications. [After FAA]

1. In computer technology, the state or condition of a device or equipment that is not under the direct control of another device.
2. In computer technology, the status of a device that is disconnected from service.

An optical system in which the optical axis of the aperture is not coincident with the mechanical center of the aperture.
Note: The principal applications of off-axis optical systems are to avoid obstruction of the primary aperture by secondary optical elements, instrument packages, or sensors, and to provide ready access to instrument packages or sensors at the focus. The engineering… (Read More →)

1. In telephony, the condition that exists when an operational telephone instrument or other user instrument is in use, i.e., during dialing or communicating.
Note: Off-hook originally referred to the condition that prevailed when the separate earpiece, i.e., receiver, was removed from its switchhook, which extended from a vertical post that also supported the microphone, and which connected the instrument… (Read More →)

Synonym hotline.

In telephony, of a circuit, a signal indicating seizure, request for service, or a busy condition.

1. Pertaining to the operation of a functional unit when not under the direct control of the system with which it is associated.
Note 1: Off-line units are not available for immediate use on demand by the system.
Note 2: Off-line units may be independently operated.
2. Pertaining to equipment that is disconnected from a system, is not in operation,… (Read More →)

A particular form of authentication information binding an entity to a cryptographic key, certified by a trusted authority, which may be used for authentication without directly interacting with the authority [10181-2].

[A] cryptosystem in which encryption and decryption are performed independently of the transmission and reception functions. [INFOSEC-99]

The process of recovering nonprotected message traffic by use of an off-line processor or central processing unit.

Storage that is not under the control of a processing unit.

The process by which telephone calls that originate or pass through private switching systems in transmission networks are extended to stations in a public switched telephone system.

An extension telephone, PBX station, or key system station located on property that is not contiguous with that on which the main telephone, PBX, or key system is located.

1. In radio communications systems, pertaining to a station that is completely shut down, i.e., that is not transmitting any signal, not even an unmodulated carrier.
2. In a radio station, pertaining to a particular source of modulation, such as a specific microphone, that is disconnected, i.e., is no longer capable of modulating the carrier.
Note: The carrier may continue… (Read More →)

1. In radio net operations, the listening, by the net-control station, to the transmissions of stations in the net, particularly to check the quality of their transmissions.
Note: Off-the-air monitoring is usually performed during periods when the net-control station is not transmitting.
2. The listening, by a radio station, to its own transmissions by receiving the signal that has been… (Read More →)

Pertaining to equipment already manufactured and available for delivery from stock.

The total load submitted to a trunk group. This value may be corrected for retrials during the engineering process. [T
1. Rpt 11-1991]

Prior to divestiture, numbers that were assigned to offices according to their hierarchical function in the U. S. public switched telephone network.
Note 1: The following class numbers are used:Class 1: Regional Center (RC)
Class 2: Sectional Center (SC)
Class 3: Primary Center (PC)
Class 4: Toll Center (TC) [Only if operators are present; otherwise Toll Point (TP)]
Class 5:… (Read More →)

In encryption, the process of applying Exclusive-OR logic to a target value and a known count. [After X9.17]

The process of encryption by using a key that has been offset. [After X9.28]

In information assurance, a track written at a nonstandard position on a diskette, as part of a method of copy protection. [2382-pt.8]

Abbreviation for optical fiber, nonconductive.
Note: OFN is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain no electrically conductive component, and which are not certified for use in plenum or riser applications. [After FAA]

Abbreviation for optical fiber, nonconductive, plenum.
Note: OFNP is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain no electrically conductive component, and which are certified for use in plenum applications. [After FAA]

Abbreviation for optical fiber, nonconductive, riser.
Note: OFNR is the designation given by the National Fire Protection Association (NFPA) to interior fiber-optic cables which contain no electrically conductive component, and which are certified for use in riser applications. [After FAA]

Open Grid Forum

Open Grid Services Architecture

Old Intercarrier Communication Process

Optical Internetworking Forum

A synchronized network in which the timing of all clocks is controlled by a selected few clocks.

Old Local Service Provider

Optical Line Terminal

Open Mobile Alliance

ONT (Optical Network Terminal) Management Control Interface

ONT (Optical Network Terminal) Management Control Interface

A global radionavigation system that enables user with special receivers to obtain position information by measuring phase difference between precisely timed signals radiated by a network of eight transmitting stations deployed worldwide.
Note: The transmitted signals time-share transmission on frequencies of
1
0. 2,
1
1. 05,
1
1. 33, and
1
3. 6 kHz. Since the transmissions are coordinated… (Read More →)

Object Management Group

An antenna that has a radiation pattern that is nondirectional in azimuth.
Note: The vertical radiation pattern may be of any shape.

A radionavigation land station in the aeronautical radionavigation service providing direct indication of the bearing (omnibearing) of that station from an aircraft. [NTIA]

See on-line. Alternate spellings: on-line, online.
Note: These alternate spellings are inconsistent with convention, but are widely used in computer technology.

A low-powered mobile station in the maritime mobile service intended for use for internal communications on board a ship, or between a ship and its lifeboats and liferafts during lifeboat drills or operations, or for communication within a group of vessels being towed or pushed, as well as for line handling and mooring instructions. [NTIA] [RR]

1. In telephony, the condition that exists when an operational telephone, or other user instrument, is not in use.
Note: On-hook originally referred to the storage of an idle telephone receiver, i.e., separate earpiece, on a hook that extended from a vertical post that supported the microphone also. The hook was mechanically connected to a switch that automatically disconnected the… (Read More →)

In telephony, of a circuit, a signal indicating a disconnect, unanswered call, or an idle condition.

A state in which the customer installation (CI) presents a high-resistance path at the network interface. [T
1. Rpt37-1994]

1. Pertaining to the operation of a functional unit when under the direct control of the system with which it is associated.
Note 1: On-line units are available for immediate use on demand by the system without human intervention.
Note 2: On-line units may not be independently operated.
2. Pertaining to equipment that is connected to a system, and is… (Read More →)

A particular form of authentication information, certified by a trusted authority, which may be used for authentication following direct interaction with the authority [10181-2].

[A] cryptosystem in which encryption and decryption are performed in association with the transmitting and receiving functions. [INFOSEC-99]

An extension telephone, PBX station, or key system station located on property that is contiguous with that on which the main telephone, PBX, or key system is located.

Customer-owned metallic or optical-fiber communications transmission lines, installed within or between buildings.
Note: On-premises wiring may consist of horizontal wiring, vertical wiring, and backbone wiring, and may extend from the external network interface to the user work station areas. It includes the total communications wiring to transport current or future data, voice, LAN, and image information.

A pictorial representation of a pushbutton on a display screen, which functions as a binary control, for example, on/off. [T1.232-1996]

1. In radio communications systems, pertaining to a station that is transmitting a carrier, whether or not the carrier is modulated.
2. In a radio station, pertaining to a particular source of modulation, such as a specific microphone, that is connected, i.e., is capable of modulating the carrier.

Abbreviation for open network architecture.

Code in which plain text elements and their accompanying code groups are arranged in alphabetical, numerical, or other systematic order, so one listing serves for both encoding and decoding. One-part codes are normally small codes used to pass small volumes of low-sensitivity information. [INFOSEC-99]

Cryptosystem employing key used only once. [INFOSEC-99]

1. [A] manual one-time cryptosystem produced in pad form. [INFOSEC-99]
2. The one time pad is the ONLY encryption scheme that can be proven to be absolutely unbreakable! It is used extensively by spies because it doesn't require any hardware to implement and because of its absolute security. This algorithm requires the generation of many sets of matching encryption keys… (Read More →)

Communication in which information is always transferred in only one preassigned direction.
Note 1: One-way communication is not necessarily constrained to one transmission path.
Note 2: Examples of one-way communications systems include broadcast stations, one-way intercom systems, and wireline news services.

1. A method of encryption used where a requirement exists to prevent the decryption of the cipher text, given full information about the algorithm [CESG].
Note: Often used for encryption of passwords and integrity checksums.
2. Synonym irreversible encryption.

1. A transfer function f which is relatively easy to compute, but for which, for a general value, y , within the selected range, it is computationally difficult to find a value x within the expected domain such that f(x) = y. There may be several values for y , for which finding x is not computationally difficult. [After X.509]… (Read More →)

Synonym simplex operation.

A component which allows the transfer of information from one system to another, whilst providing a high level of confidence that information flow in the reverse direction is prevented [CESG].
Note: Used where the security class of the receiving system dominates that of the sender.

Synonym half-duplex operation.

A trunk between two switching centers, over which traffic may be originated from one preassigned location only.
Note 1: The traffic may consist of two-way communications; the expression "one way" refers only to the origin of the demand for a connection.
Note 2: At the originating end, the one-way trunk is known as an "outgoing trunk"; at the other end,… (Read More →)

A channel capable of transmission in only one direction, which cannot be reversed. Synonym unidirectional channel.

A computer system that is a part of, or is embedded in, a larger entity, such as a communications system, and that interacts in real or near-real time with the entity and its users.

A process in which images or listings of goods and services are viewed remotely via electronic means, e.g., a vendor's Web site, items are selected for purchase, and the transaction is completed electronically with a credit card or an established credit account.
Note: Various encryption schemes may be, and usually are, used to reduce the risks of sending sensitive information,… (Read More →)

In computer networking, a software modification or installation performed remotely from an originating site (e.g., by authority of a network administrator) on a subject user's computer, by means of a special utility program that enables access to the subject computer whenever it is powered up and on line.
Note: An online software upgrade may be performed (a) automatically, without the… (Read More →)

Old Network Service Provider

Optical Network Terminal

Optical Network Unit

Out of Band

A mechanism by which a program can manipulate data structures of any format, without knowing what that format might be [POSIX.6].

1. In communications, a circuit available for use.
2. In electrical engineering, a circuit that contains an essentially infinite impedance.
Note: An open circuit may be intentional, as in a switch, or may constitute a fault, as in a severed cable.

The term "Open Circuit Test Line" denotes an arrangement in an end office which provides an ac open circuit termination of a trunk or line by means of an inductor of several Henries.

A dual bus in which the head-of-bus functions for both buses are at different locations.

In the context of the FCC's Computer Inquiry III, the overall design of a communication carrier's basic network facilities and services to permit all users of the basic network to interconnect to specific basic network functions and interfaces on an unbundled, equal-access basis.
Note: The ONA concept consists of three integral components: (a) basic serving arrangements (BSAs), (b) basic service… (Read More →)

Public specifications that are maintained by an open, public consensus process to accommodate new technologies over time and that are consistent with international standards [POSIX.0].

Storage of classified information within an accredited facility, but not in General Services Administration approved secure containers, while the facility is unoccupied by authorized personnel. [INFOSEC-99]

An interval when the dc voltage applied between the tip and ring conductors of a line is removed, hence temporarily suspending line supervision and transmission. [T1.401-1998]

1. A system with characteristics that comply with specified, publicly maintained, readily available standards and that therefore can be connected to other systems that comply with these same standards.
2. A system that implements sufficient open specifications for interfaces, services, and supporting formats to enable properly engineered applications software:- to be ported with minimal changes across a wide range of… (Read More →)

A combination of standards-based interfaces specifying a complete interface between an application program and the underlying application platform [POSIX.0].

The comprehensive set of interfaces, services, and supporting formats, plus user aspects for interoperability or portability of applications, data, or people, as specified by information technology standards and profiles [POSIX.0].

1. The layered hierarchical structure, configuration, or model of a communications or distributed data processing system that (a) enables system description, design, development, installation, operation, improvement, and maintenance to be performed at a given layer or layers in the hierarchical structure, (b) allows each layer to provide a set of accessible functions that can be controlled and used by the… (Read More →)

Pertaining to the logical structure for communications networks standardized by the International Organization for Standardization (ISO).
Note: Adherence to the standard enables any OSI-compliant system to communicate with any other OSI-compliant system for a meaningful exchange of information.

Communications system architecture that adheres to the set of ISO standards relating to open systems architecture.

The lowest level of abstraction within the OSI standards scheme.
Note: Each OSI--Protocol Specification operates at a single layer. Each defines the primitive operations and permissible responses required to exchange information between peer processes in communicating systems to carry out all or a subset of the services defined within the OSI--Service Definitions for that layer.

The next lower level of abstraction below that of the OSI--Reference Model. The OSI--Service Definitions for each layer define the layer's abstract interface and the facilities provided to the user of the service independent of the mechanism used to accomplish the service.

In the Application Layer of the OSI--Reference Model (OSI--RM), the set of functions related to the management and status of various resources identified in all layers of the OSI--RM.

1. An abstract description of the digital communications between application processes running in distinct systems. The model employs a hierarchical structure of seven layers. Each layer performs value-added service at the request of the adjacent higher layer and, in turn, requests more basic services from the adjacent lower layer:Physical Layer: Layer
1. The lowest of seven hierarchical layers. The Physical… (Read More →)

An all-dielectric waveguide in which electromagnetic waves are guided by a refractive index gradient so that the waves are confined to the guide by refraction or reflection from the outer surface of the guide or from surfaces within the guide.
Note 1: In an open waveguide, the electromagnetic waves propagate, without radiation, within the waveguide, although evanescent waves coupled to… (Read More →)

Conductors that are separately supported with insulators on poles or towers above the surface of the Earth.
Note 1: Open wire conductors may be insulated or uninsulated.
Note 2: Open wire may be used in both communication applications and power applications.

1. In INFOSEC, an environment in which protection of data and resources from accidental or malicious acts is achieved through normal operational procedures. [After 2382-pt.8]
2. [An] environment that does not provide sufficient assurance that applications and equipment are protected against the loss of confidentiality, integrity, or availability. [INFOSEC-99]

An entity on which an operation is performed.

A set of rules defining the correct use of a Target of Evaluation [ITSEC].

An integrated collection of routines that service the sequencing and processing of programs by a computer.
Note: An operating system may provide many services, such as resource allocation, scheduling, input/output control, and data management. Although operating systems are predominantly software, partial or complete hardware implementations may be made in the form of firmware.

Synonym platform.

1. The time interval between the instant of occurrence of a specified input condition to a system and the instant of completion of a specified operation.
2. In communications, computer, and information processing systems, the time interval between the instant a request for service is received from a user and the instant of final release of all facilities by the… (Read More →)

1. The method, act, process, or effect of using a device or system.
2. A well-defined action that, when applied to any permissible combination of known entities, produces a new entity, e.g., the process of addition in arithmetic--in adding 5 and 3 to obtain 8, the numbers 5 and 3 are the operands, the number 8 is the result, and… (Read More →)

Maximum functional commonality or interworking of Business Support Systems (BSS), Operations Support Systems (OSS), network management, service provisioning, billing, et cetera across all service types (data, voice, video and any combination thereof) within the context of a Service Delivery Environment (SDE).

Protection of data from either accidental or unauthorized intentional modification, destruction, or disclosure during input, processing, storage, transmission, or output operations. [INFOSEC-99]

the information produced by the developer of a Target of Evaluation to specify and explain how customers should use it [ITSEC].

1. The set of procedures, methods, tools and standards used during system operation [CESG]. See also: Development Environment.
2. The organizational measures, procedures and standards to be used whilst operating a Target of Evaluation [ITSEC].

Key intended for use over-the-air for protection of operational information or for the production or secure electrical transmission of key streams. [INFOSEC-99]

The total power requirements for communications facilities.

1. A period during which a telecommunications service remains in an operational state.
Note: The operational state must be defined in accordance with specified criteria.
2. A performance measurement period, or succession of performance measurement periods, during which a telecommunications service remains in an operational service state.
Note: An operational service period begins at the beginning of the performance measurement… (Read More →)

During any performance measurement period, a telecommunications service condition that existed when the calculated values of specified performance parameters were equal to or better than their associated outage thresholds.

The term denoting the general classifications of services rendered to the public for which separate tariffs are filed, namely exchange, state toll and interstate toll. [47 CFR Pt.36-A]

Code composed largely of words and phrases suitable for general communications use. [INFOSEC-99]

[The] process denying to potential adversaries information about capabilities and/or intentions by identifying, controlling and protecting generally unclassified evidence of the planning and execution of sensitive activities. [NIS]

[The] Process denying information to potential adversaries about capabilities and/or intentions by identifying, controlling, and protecting unclassified generic activities. [INFOSEC-99]

A system that performs operations system functions (OSFs), that is, supports the processing of information related to operations, administration, maintenance, and provisioning for the telecommunications networks.
Note: An operations system performs surveillance and testing functions to support customer access maintenance. [After T1.210-1989]

The functional entity that provides access to an operator service from an exchange in the network. The operator service may be co-located with the exchange or located elsewhere. [T1.661-1997]

The company accepting the billing information, initiating the validation process, and recording the details of the call.

A set of services including toll and assistance, listing services and intercept, associated with the originating connection network capability. [After T1.661-1997]

A stored program electronic system associated with one or more toll switching systems which provides centralized traffic service position functions for several local offices at one location. [47 CFR Pt.36-A]

A general term, ordinarily applied to trunks between manually operated switchboard positions and local dial central offices in the same wire center. [47 CFR Pt.36-A]

Open Pluggable Edge Services

Operational Expenditure

Acronym for operations security.

See fiber amplifier, optical repeater.

In optical communications, a device used to reduce the power level of an optical signal.
Note 1: Optical attenuators used in fiber optic communications systems may use a variety of principles for their functioning. Those using the gap-loss principle are sensitive to the modal distribution ahead of the attenuator, and should be used at or near the transmitting end, or… (Read More →)

1. Of a refractive or reflective optical element, the straight line that is coincident with the axis of symmetry of the surfaces.
Note: The optical axis of a system is often coincident with its mechanical axis, but it need not be, e.g., in the case of an off-axis parabolic reflector used to transmit signals to, or receive signals from, a… (Read More →)

See beamsplitter.

See fiber optic cable.

See cable assembly.

The optical signal that results from an optical conversion of an synchronous transport signal 1 (STS-1 signal). It is this signal that will form the basis of the interface. [T1.105-1988]

A region bounded by two or more mirrors that are aligned to provide multiple reflections of lightwaves.
Note: The resonator in a laser is an optical cavity. In this sense, synonym resonant cavity.

A device used for optical character recognition.

The machine identification of printed characters through use of light-sensitive devices.

Deprecated synonym for optical fiber.

A demountable device for attaching a cabled or uncabled optical fiber to another, or to an active device such as a transmitter.
Note 1: A connector is distinguished by the fact that it may be disconnected and reconnected, as opposed to a splice, which permanently joins two fibers.
Note 2: Optical connectors are sometimes erroneously referred to as "couplers. "… (Read More →)

See directional coupler, star coupler, T-coupler.

For a given wavelength, an expression of the transmittance of an optical element.
Note 1: Optical density is expressed by log10(1/T) where T is transmittance.
Note 2: The higher the optical density, the lower the transmittance.
Note 3: Optical density times 10 is equal to transmission loss expressed in decibels, e.g., an optical density of
0. 3 corresponds to a… (Read More →)

A transducer that generates an output signal when irradiated with optical energy.

A flat, circular, plastic disk coated with material on which bits may be stored in the form of highly reflective areas and significantly less reflective areas, from which the stored data may be read when illuminated with a narrow-beam source, such as a laser diode.
Note: The bits are stored sequentially on a continuous spiral track.

See dispersion.

A filament of transparent dielectric material, usually glass or plastic, and usually circular in cross section, that guides light.
Note 1: An optical fiber usually has a cylindrical core surrounded by, and in intimate contact with, a cladding of similar geometry.
Note 2: The refractive index of the core must be slightly higher than that of the cladding for the… (Read More →)

See fiber optic cable.

See primary coating.

See sheath.

See fiber optic link.

Design allowances made to prevent or ameliorate the effects of gamma or high-energy neutron radiation or bombardment, that causes some optical fibers to darken, increase attenuation, or depart from normal operating parameters.
Note: Light sources, such as LEDs and lasers, and photodetectors, also need to be hardened to prevent similar malfunctions. [From Weik '89]

See transfer function.

See optical fiber.

See OFC.

See OFCP.

See OFCR.

See OFN.

See OFNP.

See OFNR.

In the optical regime, an element that selectively transmits or blocks a range of wavelengths, polarizations, etc. , or selectively displaces a beam, e.g., by virtue of birefringence.

See optical mixing.

In an integrated circuit or electronic module, the use of opto-electronic devices to make or facilitate connections, in lieu of a direct connection involving conducting or semiconducting materials.

In a fiber optic communications link, a point at which an optical signal is passed from one equipment or medium to another without conversion to an electrical signal.

A device that uses a short optical transmission path to accomplish electrical isolation between elements of a circuit.
Note 1: The optical path may be air or a dielectric waveguide.
Note 2: The transmitting and receiving elements of an optical isolator may be contained within a single compact module, for mounting, e.g., on a circuit board. Synonym optoisolator.

Any physical interface in a fiber optic system.
Note: Source to fiber, fiber to fiber, fiber to detector, beam to prism (or lens), fiber to lens, lens to fiber, are examples of optical junctions.

Sequences of optical pulses suitably structured to permit information transfer over an optical link.

1. In optical measurements or specifications, a pair of usually straight contiguous stripes of equal width and having a defined degree of contrast, and which are used as one means of defining or determining resolution.
Note 1: Resolution may be expressed in terms of line pairs per unit distance, or line pairs per unit angle.
Note 2: Optical "targets," consisting… (Read More →)

An optical transmission channel, including any repeaters or regenerative repeaters, designed to connect two electronic or opto-electronic communications terminals.
Note: An optical link is sometimes held to include the terminal optical transmitters and receivers, especially in the case of a communications link utilizing separate electronic terminals originally designed for metallic transmission, and retrofitted for optical transmission. [After FAA]

Optical beating, i.e., the mixing, i.e., heterodyning, of two lightwaves (incoming signal and local oscillator) in a nonlinear device to produce a beat frequency low enough to be further processed by conventional electronic circuitry.
Note: Optical mixing is the optical analog of heterodyne reception of radio signals. [After FAA] Synonym optical heterodyning.

Any device used to modify any characteristic of an optical signal (lightwave) for the purpose of conveying information.

See wavelength-division multiplexing.

Terminates the fiber network in an FTTP FTTx scenario. Typically the ONT provides the NID function. One per home subscriber.

A network element that is part of a fiber-in-the-loop system interfacing the customer analog access cables and the fiber facilities. [T1.508-1998]

1. In a medium of constant refractive index, n, the product of the geometric distance and the refractive index.
2. In a medium of varying refractive index, the integral of ns, where s is an element of length along the path, and n is the local refractive index.
Note: Optical path length is proportional to the phase shift that a… (Read More →)

The extra optical power required to account for degradations due to reflections, intersymbol interference, and mode partition noise. [T1.646-1995]

See radiant power.

In a fiber-optic communication link, the allocation of available optical power (launched into a given fiber by a given source) among various loss-producing mechanisms such as launch coupling loss, fiber attenuation, splice losses, and connector losses, in order to ensure that adequate signal strength (optical power) is available at the receiver.
Note 1: The optical power budget is usually specified… (Read More →)

In an optical communications link, the difference between (a) the optical power that is launched by a given transmitter into the fiber, less transmission losses from all causes, and (b) the minimum optical power that is required by the receiver for a specified level of performance.
Note 1: The optical power margin is usually expressed in dB. At least several… (Read More →)

A device that detects an optical signal, converts it to an electrical signal, and processes the electrical signal as required for further use.

See optical repeater.

In an optical communication system, an optoelectronic device or module that receives an optical signal, amplifies it (or, in the case of a digital signal, reshapes, retimes, or otherwise reconstructs it), and retransmits it as an optical signal.

The ratio (in dB) of optical power arriving at the interface (P1) to the optical power reflected back from the same interface (P2). [T1.106-1988]

The part of the physical plant consisting of the fiber-optic cabling and connectors interconnected to provide the transport function between two adjacent repeater locations, between a repeater location and an adjacent terminal location, or between two adjacent terminal locations. The optical section extends between the point on the optical fiber just after the transmitter optical connector and the point on… (Read More →)

1. In optical communications, a device that converts an electrical signal into an optical signal.
Note: The two most commonly used optical sources are light-emitting diodes (LEDs) and laser diodes.
2. Test equipment that generates a stable optical signal for the purpose of making optical transmission loss measurements. [After FAA]

By custom and practice, the electromagnetic spectrum between the wavelengths of the vacuum ultraviolet at
0. 001 m and the far infrared at 100 m.
Note: The term "optical spectrum" originally applied only to that region of the electromagnetic spectrum visible to the normal human eye, but is now considered to include all wavelengths between the shortest wavelengths of radio… (Read More →)

See directional coupler.

A switch that enables signals in optical fibers or integrated optical circuits (IOCs) to be selectively switched from one circuit to another.
Note 1: An optical switch may operate by (a) mechanical means such as physically shifting an optical fiber to drive one or more alternative fibers, or (b) electro-optic effects, magneto-optic effects, or other methods.
Note 2: Slow optical… (Read More →)

See power margin.

1. The product of the physical thickness of an isotropic optical element and its refractive index.
2. Of an optical system, the total optical path length through all elements.

An opto-electronic instrument used to characterize an optical fiber.
Note 1: An OTDR injects a series of optical pulses into the fiber under test. It also extracts, from the same end of the fiber, light that is scattered back and reflected back. The intensity of the return pulses is measured and integrated as a function of time, and is plotted… (Read More →)

See transmittance.

A device that accepts an electrical signal as its input, processes this signal, and uses it to modulate an opto-electronic device, such as an LED or an injection laser diode, to produce an optical signal capable of being transmitted via an optical transmission medium.

The use of optical fiber networks to transport data frames from multiple data sources over an optical wavelength channel.

Any structure having the ability to guide optical energy.
Note: Optical waveguides may be (a) thin-film deposits used in integrated optical circuits (IOCs) or (b) optical fibers.

A material that rotates the plane of polarization of light that passes through it.

Synonym FOT.

Synonym FOT.

Synonym FOT.

Pertaining to any device that functions as an electrical-to-optical or optical-to-electrical transducer, or an instrument that uses such a device in its operation.
Note 1: Photodiodes, LEDs, injection laser diodes, and integrated optical circuit (IOC) elements are examples of opto-electronic devices commonly used in optical fiber communications.
Note 2: "Electro-optical" is often erroneously used as a synonym.

See opto-electronic.

Synonym optical isolator.

Abbreviation for off-premises extension.

Open Radio Access Network

Nickname for the United States Department of Defense "Trusted Computer System Evaluation Criteria", DOD
520
0. 28-STD [CESG]. Also known as "TCSEC"

The path, relative to a specified frame of reference, described by the center of mass of a satellite or other object in space subjected primarily to natural forces, mainly the force of gravity. [NTIA] [RR]

The process of describing the past, present, or predicted position of a satellite in terms of orbital parameters. [JP 1-02]

The number of independently fading propagation paths or frequencies, or both, used in diversity reception.

The OBF provides a forum for representatives from the telecommunications industry to identify, discuss, and resolve national issues that affect ordering, billing, provisioning, and exchange of information about access service, other connectivity, and related matters.

A voice or data circuit used by technical control and maintenance personnel for coordination and control actions relative to activation, deactivation, change, rerouting, reporting, and maintenance of communication systems and services. Synonyms engineering channel, engineering orderwire, service channel.

A multiplex carrier set specifically designed for the purpose of carrying orderwire traffic, as opposed to one designed for carrying mission traffic.

See birefringence.

See splice organizer.

The connection between the termination of a user-network interface and an operator service access point that is used for communication between the user and the operator service. [T1.661-1997]

In a wideband packet node, the point that receives channelized traffic, packetizes it, and sends it into the wideband packet network. [T1.509-1995]

Information indicating a toll class of service for the call. [T1.667-1999]

The ability to dial the appropriate 7- or 10-digit test number from a subscriber line. [T1.207-2000]

A part of the routing label in a signaling message that uniquely identifies the originating point of that signaling message in a signaling network. [T1.226-1992]

The ability to dial the appropriate test line number with trunk access using the appropriate test equipment. [T1.207-2000]

The user that initiates a particular information transfer transaction.
Note: The originating user may be either the source user or the destination user.

The signaling network that initiates a non-circuit-related message containing intermediate signaling network indication (ISNI) information; this network may send subsequent messages based on the received ISNI information. [T1.118-1992]

See access originator, disengagement originator.

Synonym speed of service.

Operational Readiness Testing

A method of combining two or more digital signals that have mutually independent pulses, thus avoiding intersymbol interference.

In digital video, a sampling where the luminance and the color-difference samples are generated from pixels arranged in common, continuous vertical and horizontal lines on a rectilinear grid that remains constant field/frame to field/frame. [After SMPTE]

A device forming part of an antenna feed and serving to combine or separate orthogonally polarized signals.

Operating System

1. open service architecture,
2. open service access,
3. operator service agreements,
4. open system adapter.

An electronic circuit designed to produce an ideally stable alternating voltage or current.

On-Screen Display

Abbreviation for Open Systems Interconnection.

Abbreviation for Open Systems Interconnection--Reference Model.

1. Old Service Provider.
2. Outside plant (OSP).

Open Shortest Path First

Operations Support System

Over The Air

Over-The-Air Rekeying

Observed Time Difference Of Arrival

Abbreviation for optical time domain reflectometer.

A communications common carrier--usually an interexchange carrier--that offers communications services in competition with AT&T and/or the established U. S. telephone local exchange carriers.

Organizationally Unique Identifier

A universal personal telecommunications (UPT) call type that permits a UPT user to make calls from any terminal on any network, and have access to his/her subscribed services limited only by the serving and/or assisting network's capabilities. [T
1. Rpt 41-1995]

A feature that enables the universal personal telecommunications (UPT) user to register for outgoing calls from the current terminal address to allow outgoing calls to be made from that terminal address. When registered, upon accessing the UPT facilities, all outgoing UPT calls can be made from that terminal address for the duration specified by the UPT user (duration may also… (Read More →)

An area not included in the subscribed service. An area may be defined in terms of a state/province, NPA, LATA, etc. [T1.207-1998]

Emission on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious emission. [NTIA] [RR]

In encryption, notification using a communication means other than the primary communication means. [After X9.49]

1. Signaling that uses a portion of the channel bandwidth provided by the transmission medium, e.g., the carrier channel, which portion is above the highest frequency used by, and is denied to, the speech or intelligence path by filters.
Note: Out-of-band signaling results in a lowered high-frequency cutoff of the effective available bandwidth.
2. Signaling via a different channel (either… (Read More →)

The time during which frame alignment is effectively lost.
Note: The out-of-frame-alignment time includes the time to detect loss of frame alignment and the alignment recovery time.

Signaling performed in digital time slots that are not within the channel time slot.

A telecommunications system service condition in which a user is completely deprived of service by the system.
Note: For a particular system or a given situation, an outage may be a service condition that is below a defined system operational threshold, i.e., below a threshold of acceptable performance. See outage threshold.

That period of time between the onset of an outage and the restoration of service.

The probability that an outage will occur within a specified time period.

The sum of all the outage durations divided by the time period of measurement.

See outage.

For a supported performance parameter of a system, the value that establishes the minimum performance level at which the system is considered to remain in an operational state.
Note: A measured parameter value better than the outage threshold indicates that the system is in a system operational state.

The ability of a user to originate data calls via an ISDN. [T1.615-1992]

Multicast does not use standard destination based routing and instead relies on group membership protocols such as IGMP to help build the multicast distribution tree. Interfaces that have joined the multicast group are added to the OIF table in relation to the respective multicast group. Once added to the table, the network element will create a copy of each multicast… (Read More →)

The process of transmitting address information over a trunk from one switching center or switchboard to another.

1. Information retrieved from a functional unit or from a network, usually after some processing.
2. An output state, or sequence of states.
3. Pertaining to a device, process, or channel involved in the production of data by a computer or by any of its components.
4. Information that has been exported by a TCB [TCSEC].

Synonym radiation angle.

1. The expression of the stated power available at the output terminals of a transmitter when connected to the normal load or its equivalent.
2. Under specified ambient conditions, the expression of the power that can be delivered by a device over a long period of time without overheating.

1. In telephony, all cables, conduits, ducts, poles, towers, repeaters, repeater huts, and other equipment located between a demarcation point in a switching facility and a demarcation point in another switching facility or customer premises.
Note: The demarcation point may be at a distribution frame, cable head, or microwave transmitter.
2. In DOD communications, the portion of intrabase communications equipment… (Read More →)

See direct outward dialing.

1. The attribute of an optical fiber, the cross section of the core or cladding of which deviates from a perfect circle.
2. In an optical fiber, the degree of deviation, from perfect circularity, of the cross section of the core or cladding.
Note 1: The cross sections of the core and cladding are assumed to first approximation to be… (Read More →)

Operator Virtual Connections

Providing electronic key via over-the-air rekeying, over-the-air key transfer, or cooperative key generation. [INFOSEC-99]

Electronically distributing key without changing traffic encryption key used on the secured communications path over which the transfer is accomplished. [INFOSEC-99]

Changing traffic encryption key or transmission security key in remote crypto -equipment by sending new key directly to the remote crypto-equipment over the communication path it secures. [INFOSEC-99]

A radar system that makes use of the atmospheric reflection and refraction phenomena to extend its range of detection beyond line of sight. Over-the-horizon radars may be either forward scatter or backscatter systems. [JP 1-02]

1. The condition that prevails when the numerical aperture of an optical source, such as a laser, light-emitting diode, or optical fiber, exceeds that of the driven element, e.g., optical fiber core.
2. The condition that prevails when the beam diameter of an optical source, such as a laser, light-emitting diode, or optical fiber, exceeds that of the driven element,… (Read More →)

1. In telephony, the generation of potential traffic that exceeds the capacity of a communications system or subsystem.
2. In telephony, a count of telephone call attempts made on groups of busy trunks or access lines.
3. In telephony, traffic handled by overflow equipment.
4. In telephony, traffic that exceeds the capacity of the switching equipment and is therefore lost.… (Read More →)

Any bit other than a user information bit.

See overhead bit.

Digital information transferred across the functional interface between a user and a telecommunications system, or between functional units within a telecommunications system, for the purpose of directing or controlling the transfer of user information or the detection and correction of errors.
Note: Overhead information originated by the user is not considered to be system overhead information. Overhead information generated within… (Read More →)

An arrangement for exchange-carrier-to-interexchange carrier (EC-to-IC) outpulsing that allows seizure of the EC-to-IC trunk and initiation of outpulsing prior to completion of dialing by the calling customer. [T1.104-1988]

1. One of several segments of a computer program that, during execution, occupies the same area of main storage, one segment at a time.
2. To use repeatedly the same areas of internal storage during different stages of the execution of a program.

A larger cell that physically overlays one or more smaller cells. For example, intra-building cells may be encompassed by a larger campus cell. [T1.244-1995]

A load, placed on a device or facility, that is greater than the device or facility is capable of handling, i.e., capable of performing the functions for which it was designed.
Note: Examples of overloads are (a) traffic on a communications system greater than the traffic capacity of the system, (b) for analog inputs, voltage levels above which an analog-to-digital… (Read More →)

Synonym load capacity.

1. The condition that prevails when the instantaneous level of the modulating signal exceeds the value necessary to produce 100% modulation of the carrier.
Note 1: Overmodulation results in spurious emissions by the modulated carrier, and distortion of the recovered modulating signal.
Note 2: Overmodulation in the sense of this definition is almost always considered a fault condition.
2. The… (Read More →)

1. To preempt, manually or automatically, a prescribed procedure.
Note: For example, one might manually override a prescribed course of action programmed to occur in the event of a fault.
2. In telephony, the entering of or seizure of, a busy circuit, i.e., an occupied circuit, by a party other than those using the circuit.
Note: For example, an attendant… (Read More →)

1. In the transition of any parameter from one value to another, the transitory value of the parameter that exceeds the final value.
Note: Overshoot occurs when the transition is from a lower value to a higher value. When the transition is from a higher value to a lower value, and the parameter takes a transitory value that is lower… (Read More →)

[A] Communications path within a computer system or network designed for the authorized transfer of data. [INFOSEC-99]

Of a sinusoidal wave, an integral multiple of the frequency, i.e., the fundamental, of the wave, other than the fundamental itself.
Note 1: The first overtone is twice the frequency of the fundamental, and thus corresponds to the second harmonic; the second overtone is three times the frequency of the fundamental, and thus corresponds to the third harmonic, etc.
Note… (Read More →)

[The] Process of writing patterns of data on top of the data stored on a magnetic medium. [INFOSEC-99]

Open Virtual Machine Format