Sags
Also known as brownouts, sags are short-term decreases in voltage levels. This is the most common power problem, accounting for 87 percent of all power disturbances, according to a study by Bell Labs.

Satellite Communications
The use of geostationary orbiting communication satellites to relay transmission from one earth station to another or to several earth stations. It takes only three satellites to cover the entire Earth.

Satellite Phone
They operate both on GSM/AMPs networks and via satellite in areas where there is no coverage.

Satellite
A sophisticated electronic communications relay station orbiting 22,237 miles above the equator, moving in a fixed orbit at the same speed and direction of the earth (about 7,000 mph east to west).

SCPC
Single Channel Per Carrier. Communications architecture that places one source of information on to a single carrier (frequency domain). Economical ways to get multiple signals on one transponder.

SDH
Synchronous Digital Hierarchy. A standard for digital signal transmission within transport networks.

Server
A computer that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software, such as a WWW server, or to the machine on which the software is running.

Service Provider
A company that provides services and subscriptions to telephone, mobile phone and Internet users.

Shared Hub
Satellite communications operations center that is shared among several network users; often used for VSAT operations.

SIM Card
Subscriber Identity Module card. A small printed circuit board that must be inserted in any GSM-based mobile telephone when signing on as a subscriber. It contains subscriber details, security information and memory for a personal directory of numbers.

Single Mode Fiber
A type of fiber cable capable of transmitting light over longer distances than multimode fiber at extremely high speeds (tera and peta speeds). All of DWP’s fiber optic cables consist exclusively of single mode fiber.

Slamming
The switching of a customer’s long distance service from one company to another without the customer’s permission.

Smart Card
A plastic card with an embedded microchip (Integrated Circuit) which allows the storage, addition and processing of information

SMR
Specialized Mobile Radio. This is a term that the FCC attached to the ‘for public use’ trunking business. If a company has a wireless trunking backbone system that is open for use by the general public (for a fee), then they are an SMR.

SMS
Short Message Service. Available on digital networks, allowing messages of up to 160 characters to be sent and received via the network operator’s message center to your mobile phone.

SMTP
Simple Mail Transport Protocol. The main protocol used to send electronic mail on the Internet. SMTP consists of a set of rules for how a program sending mail and a program receiving mail should interact.

SNMP
Simple Network Management Protocol. SNMP consists of a simply composed set of network communication specifications that cover all the basics of network management in a method that poses little stress on an existing network

Spectrum
The range of electromagnetic radio frequencies used in transmission of voice, data and television.

Splice
A physical connection between the ends of two fiber strands.

Spoofing
Pretending to be someone else. The deliberate inducement of a user or a resource to take an incorrect action. Attempt to gain access to an Alarm Indication Signal (AIS) by pretending to be an authorized user.

Spread Spectrum
The transmission of a signal using much wider bandwidth and power than would normally be required. Spread spectrum also involves the use of narrower signals that are frequency hopped through various parts of the transponder.

SSL
Secure Sockets Layer. A protocol designed by Netscape Communications to enable encrypted, authenticated communications across the Internet. SSL is used mostly (but not exclusively) in communications between web browsers and web servers. URLs that begin with ‘http’ indicate that an SSL connection will be used. SSL provides three important things: privacy, authentication and message integrity.

Structured Query Language
Commonly used with database servers; powerful language used for the creation, maintenance and viewing of databases.

Subscriber Line Charge
A monthly fee paid by telephone subscribers that is used to compensate the local telephone company for part of the cost of installation and maintenance of the telephone wire, poles, and other facilities that link your home to the telephone network.

Switch
A network device that filters and forwards a piece of a message (also called packets) between LAN segments.

Synchronous Optical Network
A fiber optic communications standard established by the American National Standards Institute that covers multiple data transfer rates from 51.84 MBPS to 13.22 Gbps. It defines a physical interface, optical line rates known as optical carrier signals, frame format, and an operations, administration, maintenance, and provisioning protocol.

T-1
The US term for a digital carrier facility. A leased-line connection capable of carrying data at 1,544,000 bits per second.

T-3
A digital WAN carrier facility. A leased-line connection capable of carrying data at 44,736,000 bits-per-second.

T-4
273 Mbps, 4,032 channels.

Talk Time
The length of time a wireless device may be engaged in transmission (phone conversations, sending or receiving data) before it runs out of battery power. Talk time, expressed in hours and minutes, is much shorter than standby time because transmission requires more power.

Tandem Switch
A tandem switch, also called a tandem office or a tandem, is an intermediate point on the network. These nodes help route communications quickly and efficiently through the network by concentrating and distributing traffic. In the network hierarchy, tandem offices reside at a higher level than the central offices.

TAPI
CTI protocol. Developed by Microsoft and Intel. TAPI is designed to integrate telephony control into a users’ 32-bit desktop environment.

Tbps
Terabits. 1,000,000,000,000 bits per second.

TCP/IP
Transmission Control Protocol/Internet Protocol. A protocol used to send data in the form of individual units (called packets) between computers over the Internet. While IP takes care of handling the actual delivery of the data, TCP takes care of keeping track of the packets that a message is divided into for efficient routing through the Internet.

TDM/TDMA
Time Division Multiplex/Multiple Access. A method for combining multiple data circuits into one circuit (or vice versa) by assigning each circuit a fixed unit of time for its data transmission.

Thinnet
Thicknet and Thinnet (sometimes called ThickWire and ThinWire) are commonly used terms for the larger and smaller size of coaxial cable used in Ethernet LANs. Thicknet, also known as Thickwire, is 0.4 inches in diameter and has 50 ohms of electromagnetic impedance. Thinnet, also known as Thinwire and Cheapernet, is 0.2 inches in diameter with the same impedance as Thickwire.

Throughput Rate
The maximum repetitive rate at which a data-conversion system can operate with a specified accuracy.

Token Passing Ring LAN
A token passing ring LAN is a LAN using a deterministic access mechanism and topology, in which a supervisory frame (or token) is passed from station to adjacent station sequentially.

Toll Bypass
Avoiding the long-distance carrier network (and associated tolls) when connecting to another subscriber outside of the local area, by means of the Internet, a private network, tie lines, etc.

Toll-Free Service
Enables callers to reach a call center out of the local calling area without incurring charges.

Topology
The arrangement of cable and nodes in the network, known as the network topology, is also considered part of hardware items. The physical topology represents the physical layout of the network and is distinguished from the logical topology, which determines how communication takes place in the network.

Traffic
Messages sent and received over a communication channel and measured in Erlangs or other units.

Transciever
Combination of transmitter and receiver.

Transmission
The sending of information in the form of electrical signals over electric wires, waveguides or radio or in the form of light signals.

Transponder
The antenna-like part of the communications satellite that receives signals from the earth, translates and amplifies them, and retransmits them back to earth. Satellites have numerous transponders, typically 32.

Trunk
A circuit between two telephone exchanges or switching centers or from an exchange to a customer’s switchboard.

Trunking
In its basic definition, trunking is a method of permitting a high number of conversations over a smaller number of communications paths.

Tunneling
Like skip, this is when the atmosphere ‘flips’ over and allows radio signals to travel long distances. This generally happens in the early morning hours when the sun rises. The upper atmosphere warms before the ground air and this causes a ‘tunnel’ where the signals bounce up and down close to the ground. This lets them travel long distances and then interfere with other trunk systems.

Twisted Pair
Two insulated copper wires twisted together with the ‘twists’ or ‘lays’ varied in length to reduce potential signal interference, between the pairs. Twisted pair is the most commonly used medium for connecting telephones, computers and terminals to PABXs, supporting speeds of up to 64 kbps.

Ultra Wideband
Ultra Wideband (also known as UWB or as digital pulse wireless) is a wireless technology for transmitting large amounts of digital data over a wide spectrum of frequency bands with very low power for a short distance. Ultra wideband radio can not only carry a huge amount of data over a distance up to 230 feet at very low power (less than 0.5 milliwatts), but has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power.

UMTS
Universal Mobile Telecommunications System. The name for the third generation mobile telephone standard.

Uniform Call Distributor
Unified Call Distributor (UCD) is a simple system that distributes calls to a group of agents and provides some reports. A UCD is not as sophisticated as an ACD.

Universal Service Ordering Codes
A series of wiring configurations developed by the original Bell system for connecting customer premise equipment to the public network.

UTP
Unshielded Twisted Pair cable. Cable made from pairs of wires, which have been twisted together.

VDSL
Very high-bit rate Digital Subscriber Line. Extension of High-bit Digital Subscriber Line offers up to 52 Mbps downstream and 1.5 Mbps upstream, over distances of 1,000 to 4,000 feet.

Virtual Call Center
A distributed call center that acts as a single site for call handling and reporting purposes.

Virtual Collocation

An alternative to physical collocation in which the CAPs connect their equipment to the LECs’ facilities from a remote location and request that the LEC install the necessary electronics in its central office, which is then leased by the LEC to the CAP for charges generally higher than the charges for physical collocation.

Virtual Private Networks
VPNs are services using public network facilities augmented by network control point and service management system facilities wherein traffic is routed through the public network under computer control in a manner that makes VPN
service indistinguishable from dedicated facilities based private networks.

VISN
Virtual Integrated Sky Network is a VSAT based meshed network. Sometimes, VISN indicates a VISN indoor unit but is also used to describe a VISN network.

Voice over Frame Relay
One of two main standards regarding voice transmissions over data networks; other standard is H.323.

Voice Processing
A blanket term that refers to any combination of voice processing technologies, including voice mail, automated attendant, audiotex, voice response unit (VRU) and faxback.

VPN
Virtual Private Network typically uses the Internet as the transport backbone to establish secure links with business partners, extend communications to regional and isolated offices and significantly decrease the cost of communications for an increasingly mobile workforce. VPNs serve as private network overlays on public IP network infrastructures such as the Internet.

VSAT
Very Small Aperture Terminal. Small earth stations, usually 1.2 meter to 1.8 meter in diameter (antenna dish sizes from 0.6 meter to 3.8 meter in diameter can also be used as Very Small Aperture Terminals).

WAN
Wide Area Network. Private network facilities that link business network nodes.

WAP
Wireless Application Protocol. A free, unlicensed protocol for wireless communications that makes it possible to make advanced telecommunications services and to access Internet pages from a mobile telephone.

WDM
Wavelength Division Multiplexing. A new technology that uses optical signals on different wavelengths, to increase the capacity of fiber optic networks, in order to handle a number of services simultaneously.

Wide Area Telephone Service
Special direct distance dialing toll service whereby a subscriber installs a dedicated line arranged for either inward or outward calls (not both) between the customer’s premises and a specific geographic area.

Wink-Start
Wink-Start is a supervisory signal that consists of an off-hook followed by an on-hook signal, exchanged between two switching systems. The wink-start signal is generated by the called switch to indicate to the calling switch that it is ready to receive address signal digits.

Wireless
Communication without any physical connections between the sender and the receiver. Using the radio frequency spectrum (airways), hardware, software and technologies to transmit information.

Wireless Node
A user computer with a wireless network interface card (adapter).

X.25 Protocol
The X.25 protocol, adopted as a standard by the Consultative Committee for International Telegraph and Telephone (CCITT), is a network protocol that allows computers on different public networks to communicate through an intermediary computer at the network layer level.