sending loudness rating (SLR)The ratio in dB of the sound pressure produced by a speaker to the voltage produced by a telephone and loop as defined by ITU-T Recommendation P.79. [T1.
sending-end crossfireIn teletypewriter (TTY) systems, interference, in a given channel, caused by transmissions from one or more adjacent TTY channels transmitting from the…
sensitive information1. Information, the loss, misuse, or unauthorized access to or modification of, which could adversely affect the national interest or the conduct of…
SensitivityWhen referring to a medical test, sensitivity refers to the percentage of people who test positive for a specific disease among a group of people who have…
sensitivity label1. Information representing elements of the security label(s) of a subject and an object.
sensorA device that responds to a stimulus, such as heat, light, or pressure, and generates a signal that can be measured or interpreted.
SentinelABM system designed for light area defense against a low-level ballistic missile attack on the United States.
separate channel signalingSignaling in which the whole or a part of one or more channels in a multichannel system is used to provide for supervisory and control signals for the…
separation of dutiesIn secure communications, dividing responsibility for sensitive information so that no individual acting alone can compromise the security of the data…
separationsThe process by which telecommunication property costs, revenues, expenses, taxes, and reserves are apportioned among the operations. [47 CFR Pt.36-A]
septetA byte composed of seven binary elements. Synonym seven-bit byte.
sequenceThe linear order of nucleotides along a DNA or RNA molecule, and the process of obtaining this.
sequence number (SEQ)In a packet, a field of the packet header that is used by the terminating endpoint to determine if the packets arrive in sequence. [T1.509-1995]
sequential logic elementA device that has at least one output channel and one or more input channels, all characterized by discrete states, such that the state of each output…
serialPertaining to a process in which all events occur one after the other; for example, the serial transmission of the bits of a character according to the…
serial accessPertaining to the sequential or consecutive transmission of data into or out of a device, such as a computer, transmission line, or storage device. 2.
serial computerA computer that has a single arithmetic and logic unit. 2. A computer, some specified characteristic of which is serial; for example, a computer than…
serial portA port through which data are passed serially, i.e., one bit at a time, and that requires only one input channel to handle a set of bits, e.g.
serial transmissionThe sequential transmission of the signal elements of a group representing a character or other entity of data.
serial-to-parallel conversionConversion of a stream of data elements received in time sequence, i.e., one at a time, into a data stream consisting of multiple data elements…
series T junctionA three-port waveguide junction that has an equivalent circuit in which the impedance of the branch waveguide is predominantly in series with the…
ServerAny computer on a network that contains data or applications shared by users of the network on their client PCs.
server application processAn application process that implements all or part of the functionality defined by a service definition [ECMATR46].
service accessIn personal communications service (PCS), the ability for the network to provide user access to features and to accept user service requests specifying…
service access code (SAC)A 3-digit code in the (NPA) numbering plan area (N) format, which are used as the first three digits of a 10-digit address in a North American Numbering…
service access point (SAP)A physical point at which a circuit may be accessed. 2. In an Open Systems Interconnection (OSI) layer, a point at which a designated service may be…
service affecting limit (SAL)A parameter value consistent with minimum service objectives that are necessary to support high-speed modems.
service availabilityOf a virtual connection section, the long-term percentage of scheduled service time during which that section is available. [After T1.504-1989]
service bitA system overhead bit used for providing a network service, such as a request for a repetition or for a numbering sequence.
service codeA two-digit code used in the EC-to-IC (exchange carrier-to-interexchange carrier) facility/service selective signaling protocol and the IC-to-EC…
service controlDirection of the functions or processes used to provide a specific telecommunications service. [T1.667-1999]
service data unit (SDU)In layered systems, a set of data that is sent by a user of the services of a given layer, and is transmitted to a peer service user semantically…
service featureIn telephony, any of a number of special functions that may be specified initially, or added to, the user's basic service.
service identificationThe information that uniquely identifies an NS/EP telecommunications service to the service vendor and the service user.
service integrityThe degree to which a service is provided without excessive impairment, once obtained. [NATO]
service logicA sequence of processes/functions used to provide a specific service. [T1.667-1999]
service management access function (SMAF)The entity equivalent to the work station function between network operators and/or subscribers and network service management functional entities. [T1.
Service Management Team (SMT)An entity comprised of the Regional Bell Operating Company's (RBOCs) who were ordered by the FCC to administer the SMS/800 at the advent of portability…
service node (SN)A physical entity that contains the service control function, service data function, specialized resource function and service switching/call control…
service outageThe state of a service when (a) a network failure impairs or prevents the initiation of new requests for the service, (b) continued use of the service is…
service planThe rate plan you select when choosing a wireless phone service. A service plan typically consists of a monthly base rate for access to the system and a…
service probabilityThe probability of obtaining a specified (or higher) grade of service during a given period of time.
service signalsSignals that enable data systems equipment to function correctly, and possibly to provide ancillary facilities. Synonym housekeeping signals.
service subscriber (SS)An entity that contracts for services offered by service providers. [T1.667-1999]
service switching and control point (SSCP)A physical entity that contains the service control function, service data function and the service switching/call control functions. [T1.667-1999]
service switching function (SSF)The set of processes that provide for interaction between a call control function and a service control function. [T1.667-1999]
service termination pointThe last point of service rendered by a commercial carrier under applicable tariffs.
service userAn individual or organization, including a service vendor, that is provided a telecommunications service for which a priority level has been requested or…
service-provider portabilityA faculty that allows an end user to retain the same directory number after changing from one service provider to another. [After T1.708-1998]
serving area IDInformation that identifies the local serving area where the network provider operates. [After T1.667-1999]
session keyAn encryption key that provides privacy during a call and may be changed dynamically by the system. [T1.Rpt22-1993]
Session LayerSee Open Systems Interconnection--Reference Model.
SetThree of a kind when you have two of the rank in your hand, and there is one on the board.
set-topReferring to an auxiliary device that usually rests on top of or adjacent to a television receiver and that is used in direct analog or digital satellite…
seven-hundred (700) serviceA personal telephone service that allows individuals to receive, via a single number, telephone calls in various locations (e.g.
severely errored second (SES)A one-second period that contains >30% errored blocks or at least one severely disturbed period.
severely errored unit of time1. A specified period of time, during which bits are transferred from a source to a destination, where 30% of the blocks received are errored, or at least…
sextetA byte composed of six binary elements. Synonym six-bit byte.
SFa type of form designation such as Form SF51, meaning a Standard Form used throughout the Federal Government
SFTSAbbreviation for standard frequency and time signal. See standard time and frequency signal service.
SGMLStandard Generalized Markup Language (Computer term).
shadowIn secure systems, a permutation of the bits in a byte or other data unit, which permutation is used to increase redundancy during the signature process.
shadow lossThe attenuation caused to a radio signal by obstructions in the propagation path. 2.
shannon (Sh)The unit of information derived from the occurrence of one of two equiprobable, mutually exclusive, and exhaustive events.
Shannon's lawA statement defining the theoretical maximum rate at which error-free digits can be transmitted over a bandwidth-limited channel in the presence of noise…
shaping networkA network inserted in a circuit for the purpose of improving or modifying the waveform of signals.
shared service link connectionA service link connection that can be used by any service customer (SC) in a predefined set of SCs on a first-come, first-service-basis; that is, during a…
sharewareSoftware available for downloading from public networks and bulletin board systems, usually at little cost.
sharpnessThe informal, subjective evaluation of detail in the clarity or resolution seen in an image.
sheathOf a communications or power cable, the outer covering or coverings of tough material, often plastic, that is resistant to environmental hazards such as…
sheath kilometersThe actual length of cable in route kilometers. [47 CFR Pt.36-A]
sheath milesThe actual length of cable in route miles. [47CFR]
SHIELDShield (screen) A screen to shield a rain-gauge from the influence of the wind, or to shield a thermometer against insolation.
shielded enclosure[A] room or container designed to attenuate electromagnetic radiation. [INFOSEC-99]
shielded pairA 2-wire transmission line surrounded by a sheath of conductive material that protects it from the effects of external fields and confines fields produced…
shielded twisted pairA transmission line composed of a twisted 2-wire metallic transmission line surrounded by a sheath of conductive material that protects it from the…
ShieldingA protective barrier, usually a dense material, which reduces the passage of radiation from radioactive materials to the surroundings.
shielding effectivenessThe factor that expresses the attenuation caused by scattering, e.g., of radiant or acoustic energy, during its passage through a medium.
shiftThe movement of some or all of the characters or bits of a word by the same number of character or bit positions in the direction of a specified end of a…
shift registerA storage device, usually in a central processing unit (CPU), in which device a serially ordered set of data may be moved, as a unit, into a discrete…