Telecom Dictionary

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SAFENET 
survivable adaptable fiber-optic embedded network

Satellite Communications
Satellite communications entails microwave radio, line-of-sight propagation from a transmitting 
earth terminal (i.e., usually ground-based but potentially ship or airborne) through the 
atmosphere and outer space media to a satellite, and back to earthbound receiving terminals. In 
essence, satellites are equivalent to orbiting microwave repeaters.

Scenario
In SWAT, a scenario is an iteration of an RFW project. A scenario holds the design detail work 
units that are associated with the project. By creating multiple scenarios, you can compare 
pricing and scheduling options. A scenario has three different statuses. A Working status 
indicates that the scenario is under reivew. A Posted status indicates that a scenario has been 
identified as the official design. A Final Posted status indicates that a scenario is the "as-built" 
version of the project.

SDH 
synchronous digital hierarchy

SDN 
software defined network

SECAB
Small Exchange Carrier Access Billing

Server
In a network, a server is equipment that makes available file, database, printing, facsimile, 
communications or other services to client terminals/stations with access to the network. A 
gateway is a server that permits client terminal/station access to external communications 
networks and/or information systems.

Service Management System (SMS)
In virtual private networks, SMS is a facility used to build and maintain a VPN database allowing 
customers to program specific functions for unique business applications. The SMS contains 
complete specifications of customer defined private network specifications including location 
data, numbering plan, features, screening actions, authorization codes, calling privileges, etc. 
This information is downloaded (transmitted) to network control points (NCPs) which implement 
its instructions on a customer-by-customer basis.

Service Order (SO)
A service order is a record that describes a customer request to establish, change, or terminate a 
service. The service order contains all information required to meet a customer's needs. 

SF 
single frequency

Shielded Twisted Pair
Shielded twisted pair is twisted copper paired wire cable with an outer metallic sheath 
surrounding insulated conductors. See unshielded twisted pair.

Signal
A signal is usually a time-dependent value attached to an energy propagating phenomenon used 
to convey information, for example, an audio or sound signal in which the data is characterized in 
terms of loudness and pitch.

Signaling
Signaling is the process of generating and exchanging information between components of a 
telecommunications system to establish, monitor, or release connections (call handling functions) 
and to control related network and system operations (other functions).

Signaling System No. 7, SS #7
SS#7 is an international common channel signaling system recommendations established by the 
CCITT.

Simple Network Management Protocol (SNMP)
SNMP is the application protocol offering network management service in the Internet suite of 
protocols. A structure for formatting messages and transmitting information between reporting 
devices (agents) and data collection programs. Developed jointly by the Department of Defense, 
industry and the academic community as part of the TCP/IP protocol suite; ratified as an Internet 
standard in Request for (Comment (RFC) 1098.

Simplex
Simplex is a transmission path capable of transmitting signals in only one direction.

Single Mode Optical Fiber(s)
Single mode optical fibers have sufficiently small core diameters in relation to the wavelength 
(frequency) of operation that electromagnetic (light) wave is constrained to travel in only one 
transverse path from transmitter to receiver. This requires the utmost in angular alignment of 
light emitting devices at points where light enters the fiber and results in higher 
transmitter/termination costs than multimode fiber systems. See multimode optical fiber(s).

SMDR 
station message detail record

SMDS 
switched multimegabit data system

SMT 
station management technology

SNA 
Systems Network Architecture

SNI 
subscriber network interface

SNMP 
Simple network management protocol. See Simple Network Management Protocol (SNMP).

SO
Service Order

SOC
Service Order Code

SONET 
synchronous optical network

Space Division
Space division is a switch that implements the switch matrix using a physical, electrical, spatial 
link. Where older space division switches used electro-mechanical mechanisms with metallic 
contacts, modern space-division switches are implemented electronically using integrated circuits. 
(Usually denoted by "S" in combined time and space division switches).

Special Services
Special services are any of a variety of LEC and IXC switched, non-switched, or special rate 
services that are either separate from public telephone service or contribute to certain aspects of 
public telephone service. Examples include PBX tie trunks, foreign exchange (FX) and private line 
services. These services are important to business telecommunication planners/users.

SSN 
switched service network

SS 
signaling system

Station Equipment
Station equipment is a component of telecommunications systems such as a telephone or data 
terminal, generally located on the user's premises. Its function is to transmit and receive user 
information (traffic), and to exchange control information with the network to access 
communications services.

STM 
synchronous transfer mode

STP 
shielded twisted pair or signaling transfer/point

Superframe Format (SF)
Superframe format is a framing format (D3/D4--mode 3), the most widely used T1 carrier 
framing format in which the bipolar bit stream is organized into superframes each consisting of 
12 frames. To ensure timing, the signal must consist of at least one "1" bit in every 15 bits and at 
least :3 " 1" bits in every 24 bits. See extended superframe.

Supervisory Signals
Supervisory signals are signals used to indicate or control the states of circuits involved in a 
particular switched connection. A supervisory signal indicates to equipment, to an operator, or to 
a user that a particular state in the call has been reached and may simplify the need for action.

Switch Matrices
Switch matrices are the mechanism that provides signal paths between its input and output 
terminations. Modern matrices are electronic and involve either time or space division switching. 
A time division switch employs a TDM process, in a time-slot interchange (TSI) arrangement. In 
space division, a physical, electrical, spatial link is established through the switch matrix. 
Whereas older space division switches used electro-mechanical mechanisms with metallic 
contacts, modern space-division switches are implemented electronically using integrated circuits.

Switching
Switching refers to the process of connecting appropriate lines and/or trunks to form a desired 
communications path between two station sets, or more generally, any two arbitrary points in a 
telecommunications network. Included are all kinds of related functions such as signaling, 
monitoring the status of circuits, translating address to routing instructions, alternate routing, 
testing circuits for busy conditions, and detecting and recording troubles.

Switching Systems
Switching systems are interconnect transmission facilities at various network locations and route 
traffic through a network.

Systems (Manual Circuits)
In Plant Records and Assignment, these terms refer to circuits whose network elements have 
been assigned manually rather than by automatic assignment.

Systems Network Architecture (SNA)
SNA is IBM's proprietary description of the logical structure, formats, protocols, and operational 
sequences for transmitting information units through and controlling network configuration and 
operation.