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Glossary of broadband terminology: C

Cable Binder: In the telephone network, multiple insulated copper pairs are bundled together into a cable called a cable binder.
Cable Modem: A modem designed to operate over cable TV lines; used to achieve extremely fast access to the Internet.
Campus Area Network: A network that involves interconnectivity between buildings in a set geographic area, such as a campus, an industrial park,or other such private environment.
Carrier Service Area: Area served by a LEC, RBOC, or telco, often using DLC technology.
Carrierless Amplitude and Phase Modulation: Licensed by GlobeSpanTechnologies, Inc., this modulation is based on QAM and is used in ADSL modems. CAP is a competitor to DMT modulation. Regardless of its standards status, it is used in many telephone companies' ADSL trials.
Category 3 Cabling: A rating for twisted pair copper cabling that is tested to handle 16 MegaHertz of communications. Handles 10 Mbps of LAN traffic and is commonly used as telephone wiring.
Category 5 Cabling: A rating for twisted pair copper cabling that is tested to handle 100 MegaHertz of communications. CAT-5 cable is generally required for higher-speed data communications, such as Ethernet LANs and possibly low-speed ATM.
Category 6 Cabling: A rating for twisted pair copper cabling that is tested to handle up to 1000 MegaHertz of communications.
Central Office: A circuit switch that terminates all the local access lines in a particular geographic serving area; a physical building where the local switching equipment is found. xDSL lines running from a subscriber's home connect at their serving central office. See also Serving Central Office.
Channel: A generic term for a communications path on a given medium; multiplexing techniques allow providers to put multiple channels over a single medium. See also Multiplexer.
Channel Service Unit/Data Service Unit: A digital interface device that connects end user data communications equipment to the digital local access lines.
Circuit Switched Network: A network that establishes a physical circuit temporarily on demand (typically when a telephone or other connected device goes off hook) and keeps that circuit reserved for the user until it receives a disconnect signal.
Circuit Switching: A switching system that establishes a dedicated physical communications connection between endpoints, through the network, for the duration of the communications session; this is most often contrasted with packet switching in data communications transmissions. See also Packet Switching.
CLECs: Competitive Local Exchange Carriers
Client/Server Architecture: A distributed computing model that involves distributing information resources in servers that are accessed by so-called clients, the end users. This is generally opposed to centralized mainframe computing architecture.
C.O.: Central Office
Coder/Decoder: A hardware device or software program that converts analog information streams into digital signals, and vice versa; generally used in audio and video communications where compression and other functions may be necessary and provided by the CODEC as well.
Commercial End User: See Service User.
Community Antenna Television: Also known as Cable TV.
Competitive Access Provider: See Carrierless Amplitude and Phase Modulation.
Competitive Local Exchange Carrier: A LEC which, when competition begins, has the less dominant position in the market; the carrier entering the market, challenging the ILEC market position.
Compression: The act of sampling and reducing a signal for the purposes of saving storage or transmission capacity; MPEG1 and MPEG2 are two key encoding and compression algorithms that enable full-motion video over smaller bandwidth circuits, such as those offered by ADSL, SDSL, and HDSL.
Concentrator: A device that serves as a point of consolidation of network links so that multiple circuits may share common limited network resources.
Connection Oriented: A term applied to network architecture and services which require the establishment of an end-to-end, predefined circuit prior to the start of a communications session. Frame relay circuits are examples of connection-oriented sessions. See Connectionless.
Connectionless: A term applied to network architecture and services which do not involve the establishment of an end-to-end, predefined circuit prior to the start of a communications session. Cells or packets are sent into the connectionless network, and are sent to their destination based on addresses contained within their headers. The Internet and SMDS are two examples of connection-less networks. See Connection Oriented.
Constant Bit Rate: Specifies a fixed bit rate so that data is sent in a steady stream. This is analogous to a leased line.
Consultative Committee for International Telegraph and Telephone: Thef ormer international standards body that developed telecommunications standards; now called the International Telecommunications UnionTelecommunications Standards Sector (ITUTSS).
Core Network: Combination of switching offices and transmission plants connecting switching offices together. In the US, local exchange CoreNetworks are linked by several competing Interexchange networks; in the rest of the world, the Core Network extends to national boundaries.
CPE: Customer Premises Equipment
Crosstalk: Interference on an analog line of an adjacent signal with the intended receive signal. Crosstalk makes it hard to hear just the intended signal, as there are multiple conversations on the line at once.
Customer Premises Equipment: A wide range of customer premises-terminating equipment which is connected to the local telecommunications network. This includes telephones, modems, terminals,routers, set top boxes, etc.
CWSS: Copper Wideband Serving Section
Cyclic Redundancy Check: A test used to confirm that data has been delivered without error. In a data packet, the CRC character is calculated by assigning binary values to blocks of data. If the block of data does not match its assigned CRC value upon delivery, the data is errored.