Glossary of Terms
1G
First generation wireless analog wireless phones.
2G
Second generation wireless
digital wireless phones
3G
Third generation wireless
high-speed, multimedia data and voice
10BaseT
Ethernet Standard for local area networking which runs at 10Mbps.
100BaseT or 100BaseFx
Ethernet standard that transmits data at 100 Mbps over a local area network (LAN). Typically used for file server connections.
Access Point (AP)
A device that provides network access to wireless clients, often a PC router equipped with wireless card.
ADSL
Asymmetric Digital Subscriber Line, a specific type of DSL geared towards the home/small office (See DSL). With ADSL the speed used to transmit information from the device (e.g., PC, Server) is a fraction of the speed used to receive information at the device. See DSL.
Analog
Pertaining to data that is transmitted in continuously quantities, not digital. Can take on any value with in a range, similar to a wall clock or voice wave.
ATM
Asynchronous Transfer Mode is a relatively new protocol based on an architecture switching of small 53 byte cells. It supports data networking at high speeds (OC3, OC12, OC48, etc.) Inherently designed to carry voice and video while maintaining high quality over a single facility. ATM uses the same technology and protocols in the LAN and WAN.
B-Channel
64 Kbps transmission channel/path which is used in ISDN to pass voice/data.
Bandwidth
The difference, expressed in Hertz between the highest and lowest frequencies of a range of frequencies. Also, commonly used as the speed that a data transmission requires to operate effectively.
Bit
Binary digit, the lowest denominator in a computer system. A bit has two settings, On or Off, normally represented as a '1' for On or a '0' for Off. Combinations of bits are normally strung together to represent characters, numbers or execution instructions in a computer.
Broadband
The capability of digital technology to combine & transport multiple forms of communications media, including audio, text, data, music, video and other formats. The physical pathway can use one or more transmission media, such as copper/coaxial wire, optical fiber, digital broadcast, satellite or radio spectrum. Transmission capacity is faster than 200 Kbps.
Byte
A term used for a group of 8 adjacent bits which represents a character, e.g. a letter or a number.
CAT5 or CAT5 UTP
Category 5 unshielded twisted pair wire. Physical media used to connect devices (e.g., PCs, printers, servers) together. Allows for Local Area Network (LAN) transmissions to at least 100Mbps, usually within 100 meters of a wiring closet.
Cable Modem
A device which allows high speed attachment (up to 10Mbps) to a cable network for Internet access. Examples are Roadrunner and Optimum Online. The end device connects to the cable modem through an Ethernet connection.
Centrex
Central office telephone equipment serving subscribers at one location on a private automatic branch exchange basis. The system allows such services as direct inward dialing, direct distance dialing, and console switchboards.
CLEC
Competitive Local Exchange Company is a service provider who provides competitive communications services in the ILEC's territory.
CO
Central Office, the building, owned by the local exchange company (ILEC) which houses the telephone and data switching equipment.
COAX
Coaxial cable, a cable consisting of one conductor, usually a small copper wire within, and insulated from, another conductor of larger diameter, usually a copper tubing or copper braid.
CODEC
A COder DECoder is used for coding analog data (e.g. Voice) for transmission over digital lines.
Committed Information Rate (CIR)
The amount of bandwidth that is guaranteed by the service provider in a Frame Relay network.
CPE
Customer Premise Equipment is telecommunications equipment that is owned by the customer and maintained at their site. This equipment can be leased from the service provider for a fee (e.g. DSU/CSU or PBX).
CSU
Channel Service Unit, is the circuit termination point for the LEC's incoming line. It provides error detection, keep alive, and remote loopback the carrier can use when diagnosing line problems.
Dark Fiber
Fiber that has been installed but currently is not used (or "lit"). It is provisioned for future expansion and may or may not be terminated in a patch panel.
Dial-up
A voice line up to 56K used for access to a computer or the Internet via a modem.
Demarc
Demarcation Point, the point at which the subscriber wiring connects to the local phone company wiring. Usually a jack on the wall.
DID
Direct Inward Dial allows a caller to dial a number that is unique to a user in a company without going through a company operator.
Digital
Is a discrete data transmission. Can only take on a limited set of values. Similar to a light switch.
DSL
Digital Subscriber Line is a communication technology usually offered by telephone companies that uses existing twisted-pair telephone lines to transport high-bandwidth data, such as Internet, multimedia, and video. SDSL and ADSL are the two varieties of DSL services ADSL is drawing significant attention from service providers because it promises to deliver high-bandwidth data rates to dispersed locations with relatively small changes to the existing telephone company infrastructure at a reasonable cost. Download speeds can range from 128 Kbps to 6 Mbps from the service providers. DSL has a geographical limitation for customers of about 15,000 feet from the CO.
DSU
Data Service Unit, converts the synchronous digital signal from the user's equipment (PC, router, etc.) to a T-Carrier bipolar signal.
Ethernet
The most prevalent technology used to interconnect PC, printers, etc. in a local area network. Uses a "party line" concept as multiple people share the Ethernet bandwidth. Transmission speeds vary from 10 Mbps to 1Gbps. Many different types of Ethernet connections can exist in a customer environment, usually based on speed and media types (fiber and copper). See 10Base2, 10BaseT, 100BaseTX, 100BaseFX, 1000BaseLX.
Fast Ethernet
Ethernet standard that transmits data at 100 Mbps over a local area network (LAN). Typically used for file server connections.
FCC
Federal Communications Commission governs Interstate telecommunications.
FDDI
Fiber Distributed Data Interface, an older LAN technology to allow high speed connections. Traditionally used for backbone network connections at speeds of 100 Mbps over a fiber optic LAN.
Firewall
A device (hardware and software) which protects a user's internal network from an outside "hostile" network. Commonly used when a business connects to the Internet.
Frame Relay
A wide area network technology based on packet switching. It allows for different speeds at different locations. Utilizes a permanent virtual circuit (PVC) to connect locations. Allows for contracting a guaranteed bandwidth (CIR) between locations with the ability to burst for some period of time, if available. It is very common to use this technology when there are many geographically dispersed locations which need to be interconnected.
GB
1,000,000,000 bytes.
Gbps
1,000,000,000 bits per second, a measure of speed of the transmission rate for data across wired or wireless networks.
Gigabit Ethernet
The newest standard in high speed local area networking based on Ethernet. Transmission speed is at 1,000 Mbps or a 1Gbps.
H.323
Is a standard developed to allow audiovisual conferencing data to be transmitted over a TCP/IP network without concern for interoperability.
ILEC
Incumbent Local Exchange Company, traditionally referred to as the "local telephone company". Owner of the CO.
Internet
The public Internet is comprised of millions of users, systems, and applications interconnected using a common protocol/language (TCP/IP). Sometimes referred to as the "world wide web."
Internet Service Provider
A company which allows access to the Internet with dial-up, DSL, or cable modems. ISPs may provide other value-added services such as e-mail, Web hosting, and Domain Name Services.
Intranet
A private network that uses Internet technologies (like TCP/IP and the Web) for improved application implementation time, ease of use, and platform independence.
Integrated Services Digital Network (ISDN)
An all digital service that can incorporate voice, data on a single service facility. ISDN to homes and small businesses are known as basic rate services. (ISDN-BRI) and businesses requiring higher bandwidth will utilize primary rate (ISDN-PRI).
ISDN-BRI
Basic Rate Interface. The data rate is typically 144 Kbps with two (2) B-channels to carry voice/data traffic and one (1) D-channel for signaling.
ISDN-PRI
Primary Rate Interface. The data rate is 1.544 Mbps and provides 23 B-channels to carry voice/data traffic and one (1) D-Channel for signaling.
ISP
Internet Service Provider, a company which allows access to the Internet with technologies such as high-speed dial-up, DSL, or cable modems. ISPs may provide other value-added services such as e-Mail, Web hosting, Domain Name Services, Firewall, etc.
IXC
Inter-eXchange Carriers, also known as long distance companies which sell long distance telephone service.
KB
1,000 bytes.
Kbps
1,000 bits per second, a measure of speed of the transmission rate for data across wired or wireless networks.
Key System
Phone systems typically found in small businesses where outside calling is more important than inside. Each phone has a multiple line appearance to the central office. A user gets a line by depressing a key.
LAN
Local Area Network is a term used for high speed network within a building or campus. Evolved from the PC revolution and allows multiple users in a relatively small geographic area to exchange files, messages, and access to shared resources such as file servers and printers. Common LAN types are Ethernet, Fast Ethernet, Gigabit Ethernet, Token Ring, ATM, and FDDI.
"Last mile"
Common term used for the last few miles of most telephone companies central office (CO) to the customer premises. It's where the signaling, switching, and DC power are connected to the subscriber's phone.
LATA
Local Access and Transport Area. In the U.S., the FCC has divided the country into LATAs. All tariffs and rates for local and long-distance calls are based on LATAs.
Leased Line
A communications circuit that provides a dedicated connection between two facilities. An improvement over dial-up circuits which eliminates the need for random circuit selection. A number of line types and speeds are available from the LEC or IXC. The lines are typically 'conditioned' to provide relatively error-free transmission.
LEC
Local Exchange Company, typically provides local telephony and data circuits in a LATA.
MB
1,000,000 bytes.
Mbps
1,000,000 bits per second, a measure of speed of the transmission rate for data across wired or wireless networks.
Managed Service
An offering by a service provider which combines the supplying of telecommunication services and facilities with complementary management services, thereby eliminating the need for hiring / developing in-house skills to support the systems. Typically used for Internet services, dial-up services and Frame Relay services. Examples of managed services include installation, configuration, maintenance and management of firewalls, e-mail servers, routers, modem banks, CSU/DSUs, etc. Usually includes 24-hour monitoring and reporting.
Mesh Network
A netlike communications network in which there are at least two pathways to each node. A fully meshed network means that every node has a direct connection to every other node. Most mesh networks are partially meshed and require traversing nodes to go from each node to every other.
Mobile Internet
Refers to gaining access to the Internet using a lightweight, handheld device, such as a PDA or cell phone.
Mobile Wireless
Refers to transmission through the air from a base station to a moving device such as a cell phone.
Modem
Modulator/Demodulator is a device that transforms a digital signal so that it can be carried over analog transmission facilities. Usually operates at speeds up to 56 Kbps.
Multimode Fiber
A graded-index fiber or step-index fiber that allows more than one bound mode to propagate. Normally used in a building/campus local area network within distances of 2 kilometers or less.
Multiplexor (MUX)
This is a device used to interleave multiple inputs (data from an Ethernet LAN, Voice from a PBX, Video Codec, etc.) to allow the inputs to be carried over a single high speed facility, like a T1 circuit.
Multipoint
Refers to a communications line (network) that provides a path from one location to many. A cell phone is an example of a multipoint system.
OCx
Optical Carrier specification used in ATM/SONET the 'x' represents a multiple of 51.84Mbps transmission (OC3 = 3 x 51.84 Mbps, OC24 = 24 x 511.84 Mbps).
OC-3
Optical Carrier 3 (155 Mbps) specification used in ATM/SONET.
OC-12
Optical Carrier 12 (622 Mbps) specification used in ATM/SONET.
OSI
The Open Systems Interconnection model is a seven layer model developed by the International Standards Organization to develop standards for data communications and promote vendor interoperability.
PBX
A Private Branch Exchange is a smaller version of the telephone company's central office switch. It provides features such as call accounting, hunt groups, least cost routing of calls, toll restriction of calls by user, voicemail, etc. Usually used for companies with greater than 50-100 users.
Point-to-Point
Refers to a communications line that provides a path from one location to another (point A to point B).
POP
Point of Presence. Long distance company switches are normally referred to as the carrier Point of Presence. The switches are typically co-located with or near the local exchange carrier.
POTS
"Plain Old Telephone Service," a common name for a telephone line.
PSC
Public Service Commission, typically governs intrastate regulations with respect to telecommunications.
PSTN or Public Switched Telephone Network
This is the term which usually is the "cloud." Represents a generic term for any non-dedicated data service such as dial-up analog service.
PUC
Public Utilities Commission, typically governs intrastate regulations with respect to telecommunications.
PVC
Permanent Virtual Circuits commonly used for Frame Relay services. PVCs provide the logical connections to customer facilities. The Frame Relay / PVC technology allows for seamless rerouting of the connection in the case of a failure or congestion.
RG6
Higher grade coaxial cable used for cable modems and satellite cabling.
RG59
Standard coaxial used for cable TV (75 Ohm).
"Right of Way"
A legal agreement between two parties (e.g., a home owner and a public utility) that permits the utility to use and access the property in the manner agreed to with the property owner. Rights of way (and/or easements) are generally incorporated as provisions in the deed.
RJ11
Standard telephone jack (6 pins).
RJ45
Data Jack present on a Ethernet cable (8 pins).
Router
Is an intermediate device that forwards packets of information across successive networks, independent of the underlying media.
SDSL
Symmetric Digital Subscriber Line, with SDSL the speed used to transmit information from the device (e.g., PC, Server) is equal to the speed used to receive information at the device.
Service Provider
A provider of telecommunication services such as voice, data, video, or Internet access.
Single Mode Fiber
Usually used for long distance applications and lit with laser technology. An optical fiber in which only the lowest-order bound mode can propagate the wavelength of interest.
SMS Short Message Service
A text message service that enables short messages of generally no more than 140-260 characters in length to be sent and transmitted from a cell phone.
SONET
Synchronous Optical Network is designed to take advantage of high-speed transmission rates available with fiber. SONET is expected to eventually take the place of T-carrier facilities as the next generation of high speed time-division multiplexing. SONET speeds start as low as OC-1 (51.84 Mbps) to OC-48 (2.488 Gbps) and beyond.SONETs are generally designed as a closed loop 'ring' and are self-healing, if a break in fiber occurs, the transmissions are automatically rerouted back through the non-damaged portion of the network. SONET has redundancy built into its architecture.
Switch
A switch is a device in the central office that connects a calling telephone to the called telephone.
T1
The T-carrier facilities is the basic technology on which all traditional carrier facilities (1.544 Mbps) are based. Using time-division multiplexing, the T-1 bandwidth is divided into 24 channels of 64 Kbps each. Each channel (or combination) can be used to deliver services such as voice, video or data.
T3
A T-carrier service comprised of 28 T-1 facilities. Usually meant for very high speed voice, data, and video transmission (45Mbps). Commonly seen to extend a campus network across a WAN.
TCP/IP
Transmission Control Protocol/Internet is a common communication protocol (e.g. language) and associated application suites which are used to network computers over the Internet.
Token Ring
A local area network topology researched and developed primarily by IBM. Provides a LAN speed of 16Mbps.
Trunk
A trunk is a communication line which runs typically from a telephone service provider to a corporate phone system, PBX.
Twisted Pair
Refers to copper wire, usually in reference to interconnecting devices to a local area network (see CAT5).
URL
Universal Resource Locator, common term for the statement used in an Internet WEB browser to locate a resource (e.g. http://www.dcedc.com).
UTP
Unshielded Twisted Pair wire. The quality of the wire varies by grade, from the UTP installed for normal telephone use, to CAT5 and above used for connecting computer devices in a LAN.
Virtual Circuit
A virtual circuit is a logical circuit created to ensure reliable communications between two network devices.
Voice over IP (VoIP)
A technique for transmitting voice (analog) calls over a TCP/IP network versus a traditional carrier circuit-switched network; ideally with little or no quality difference.
Virtual Private Network (VPN)
A private network that is configured within a public network. VPNs enjoy the security of a private network via access control and encryption, while taking advantage of the economies of scale and built-in management facilities of large public networks.
VSAT
Very Small Aperture Terminal used in satellite communications. Satellite communications provides very high bandwidth capability and is typically used where terrestrial communications facilities are not available, or cannot be cost justified based on the use characteristics. VSAT is often used in environments where there is a need for high volume broadcasts to a large number of facilities (e.g., retail store chain price lists).
WAN
Wide Area Network, used when describing the interconnecting of multiple geographically dispersed sites where you must cross public rights of way. Commonly, seen using router technology to interconnect with leased lines or frame relay circuits.
WiFi
Wireless fidelity or broadband service, usually conforming to the 802.11a or 802.11b IEEE standards in the 2.4GHz frequency range.