A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Cable - Copper-based media to transport electrical voice, data, and video signals.
Call Detail Recording (CDR) - Stored information on telephone calls connected through a PBX switch. Details include number dialed, call duration for both inbound and outbound calls, and the trunk ID (or phone numb er). Each call event, such as transfer, connect, or disconnect - gets a time stamp.
Call Forwarding - Feature of some intelligent network switches and PBX's; allows calls to be rerouted automatically from one line to another.
Call transfer - The ability of a PBX system to transfer a call connection or conversation to another extension.
Call Waiting - Offered by local phone companies, allowing a caller to receive additional incoming calls.
Caller Identification (Caller ID) - Also known as Automatic Number Identification (ANI) - phone number identification is sent in a data packet down the phone line; subscribers to this service offered by local phone companies receive this data through the central office that has caller ID capability. If the central office does not have this capability, the caller ID display will read "out of area' to the called party.
Carrier - (1) Company authorized by appropriate state or federal regulatory agencies to provide telecommunications services. (2) Continuous frequency capable of being modulated or impressed with a second information carrying signal.
Carrier Common Line Charge - The fee local phone companies charge long distance carriers to connect to the far-end portion of a call.
Carrier Provided Loop - Local phone line purchased by a LD carrier, and resold as part of a WAN service.
CAT 1 - Category 1 wire; other than phone wire, used for transmission (except coax).
CAT 2 - Category 2 wire; Twisted-pair wire of 22 to 26 AWG. Used for analog telephone wire. Speeds of 1.5 MHz at 200 feet.
CAT 3 - Category 3 wire; Twisted pair wire of 22 to 24 AWG. Used for analog telephone, 10 base-T, and T1. Speeds of up to 16 MHz at 300 ft.
CAT 4 - Category 4 wire; Twisted pair wire of 22 to 24 AWG. Used for analog voice, 10 base-T, Token Ring, and T1 lines. 20 MHz at 300 ft.
CAT 5 - Category 5 wire. Twisted pair wire of 22 to 24 AWG. Each pair of wire placed side by side, each pair has a different number of twists per foot. Used for 10 base-T, Token Ring, switched Token Ring, ATM and T1. Speeds of 100 MHZ at 300 ft.
CAT 7 - Category 7. Twisted pair wire of 22 to 24 AWG. Each pair of wire placed side by side, each pair has a different number of twists per foot. Used for 10 base-T, 100 base-T, Token Ring, switched Token Ring, ATM, T1, T3, and STS-1
Central Office - The site where the local telephone company's equipment routes calls to and from customers, as well as connecting customers to ISP's and Long Distance Services. Synonyms: end office local dial office wire center, or switching center.
Central Office Connection (COC) Fee - Fee charged to telecom users for the access connection between the local central office and the interexchange carrier's facilities.
Centrex (aka Central Exchange) - routes and switches calls for commercial and non-profit organizations, managed by a Centrex service (unlike private line exchanges). Usually located at the telephone company's central office.
Channels - The path for analog or digital transmission signals; multiple channels share the same wires or fiber with services such as ISDN, T-1, T-3, etc. Synonyms: circuit, facility line, link, or path.
Channel Bank - (1) Portion of a carrier system that performs the first step of modulation. (2) Multiplexer that modulates a group of channels into a higher frequency band, and, conversely, demultiplexes the higher frequency band into individual channels (e.g., breaks a DS1 signal into the equivalent of 24 analog voice-grade channels each with 56 to 60 kbps bandwidth)
Channel Capacity - Measured in bits per second, the maximum that can be carried by a channel
Channel Loop Back - For testing a digital service line (example - T1) - by connecting the transmit channel to the receive channel at the far end of the channel. By testing at the originating location, the signal can be tested for errors. Smart jacks are an example of one type of equipment that can do this testing by remote control.
Channel Service Unit (CSU) - A hardware device, also known as a CSU/DSU (Channel Service Unit / Data Service Unit) - that acts as a demarcation point for a T1, provide line-format and line-code conversion between the customer premises equipment and public network, and to provide maintenance or alarm services and loop-back for finding problems with the T1 line or the customer's equipment.
Channel Termination - Aka Chanterm; this is a cross-connect that links the receive and transmit of 2 devices - connecting private line services through a central office. As a private line goes through central offices from its origination to its destination, each connection through a central office has a channel termination
Circuit - Digital, analog, T1, and ISDN are circuits, which is another name for a phone line. Also, circuits can also be devices which receive an input, and converts it into output.
Cisco-Certified Design Associate(CCDA) - Industry certification/training program, provided to train individuals for simple-routed LAN, WAN and switched LAN networks.
Cisco-Certified Design Professional (CCDP)- Industry certification/training program offered by Cisco systems, for training individuals for complex LAN, WAN, and switched LAN networks. Prerequisite for the CCDP program.
Cisco Certified Network Associate (CCNA) - Training individuals for installation and maintenance of routed LAN, WAN and switched LAN using Cisco Systems products.
Cisco Certified Network Professional (CCNP) - Advanced certification, of which CCNA is a prerequisite. Training for individuals for complex ISP environments using Cisco Systems network products.
Cladding - Of the two glass sections of a fiber optic line; the outer section surrounding the core.
Class-1 Central Office - In a large network hierarchy of long distance central office switches; the centermost point.
Class-2 Central Office - Older term for a network hierarchy of switch points; central offices are rapidly becoming either a class-5,4, or class-1 central office due to better connections.
Class-3 Central Office - See Class-2 Central Office.
Class-4 Central Office - A main switch center for an area code or a tandem central office - in either case, they may also perform Class 5 end connection functions.
Class-5 Central Office - A local telephone company central office - they connect to end customers.
Class A IP Address - With a total of 126 Class-A IP addresses, each supporting 16,777,216 hosts, in the range of 1.0.0.0 and 126.255.255.255, these addresses are usually allocated to large companies / governments / universities to identify their internet domain assigned by the InternIC.
Class-B IP Address - With a total of 16,384 Class-B IP addresses, each supporting 66,534 hosts, in the range of 128.0.0.0 and 191.255.255.255, these addresses are usually allocated to medium-to-large to identify their internet domain assigned by the InternIC.
Class-C IP Address - With a total of 2,097,152 Class-C IP addresses, each supporting 254 hosts, in the range of 192.0.0.0 and 223.255.255.255, these addresses are usually allocated to small corporations to identify their internet domain assigned by the InternIC.
Class-D IP Address - Used for Multicast addressing in the range of 224.0.0.0 and 239.255.255.255, these addresses can be routed by modern protocols such as Internet Control Message Protocol (ICMP_ and Cisco's Interior Gateway Routing Protocol (IGRP); protocols that can recognize multicast addresses that are not assigned to specific hosts but instead to groups of hosts on a network.
Class-E IP Address - IP addresses in the range of 240.0.0.0 and 255.255.255.254, these addresses are not assigned in a network; they are reserved for special purpose and future addressing modes.
Clear Channel - Channel in which the full bandwidth (e.g., 64 kbps) is used for transmission; no portion of the channel is set aside for control, framing, or signaling.
Clear Channel Coding (CCC) - Type of T1 service. Formatted for out of band signaling, with no bit robbing. Also, the dial tone and hood flashes, as well as DTMF digits are sent over the last (24th) channel in the T-1 circuit. Good for data circuits and in-band signaling is best for voice circuits. All 64kbps of each channel of the T1 is dedicated to signaling.
CLLI Code - Pronounced as "silly code', the 11 digit alphanumeric code that identifies physical locations in the phone network.
Coax (coaxial cable) - Shielded copper transmission wire that surrounds a central conductor with a dielectric.
Coder Decoder (CODEC) - An analog-to-digital, or digital-to-analog converter.
Central Office - Building that houses telecommunications switching systems.
Central Office Code - The central office address; corresponds to the second three digits of a phone number (also referred to as NXX).
Colocation, Physical - The physical location and interconnection agreement, where telephone companies hand off calls / services between each other - for example, where a CLEC and a RBOC transfer calls between each other.
Colocation, Virtual - An interconnection agreement between telephone companies - in this case, the CLEC requests to be connected to the RBOC's network, but all of the equipment is owned by the RBOC - the connection is not in a physical location; it is virtual.
Combination Trunk - A Direct Inward Dial and Direct Outward Dial - combined into one trunk. Just like your home phone - you can dial out, and also receive calls.
Committed Burst Size (Bc) - Maximum amount of data (in bits) that the network agrees to transfer under normal network conditions during a time interval.
Committed Information Rate (CIR) - Rate at which the network agrees to transfer committed burst size (Bc) data during normal network conditions on a permanent virtual connection (PVC). This rate is averaged over the committed measurement interval (Tc).
Committed Rate Measurement Interval (Tc) - Time interval during which data sent over a network is rated and measured.
Common Carrier - Government-regulated, private carrier that furnishes the general public with telecommunications services and facilities.
Competitive Access Provider (CAP) - Companies that offer private line services other than, or in competition with, RBOC's, in providing private line access to long-distance carriers. Services can carry the LD carrier's dial tone.
Conference Bridge - Where everyone connected to a conference call are controlled by a single source. For example, everyone on a call calls a toll free number - a conference attendant answers the call and bridges them through to the rest of the conference callers.
Conference Call - Where three or more different telephone lines, with different phone numbers and/or extensions, are connected together on one call.
Constant Bit Rate (CBR) - A quality of service that for ATM networks; undistorted delivery due to precise clocking. Used for time sensitive connections such as voice, video, or real time computing information.
Contiguous slotting - To get one larger channel - banding together 2 or more channels in a T1. Also known as a Fractional T-1 or Concatenation.
Copper Distributed Data Interface (CDDI) - Twisted pair version of Fiber Distributed Data interface. Good for speeds up to 100 Mbps. Used as a backbone for LAN environments in token passing systems.
Core Router - A device that serves as a gateway for any communications that come from its local network to other peripheral network - used in packed switched star topology, and is part of the backbone communications link.
Code Division Multiple access (CDMA) - Uses PCS forms of cell phone service, converting voice into a digital signal. An address with an ID destination code is added to ach packet which is then scrambled and transmitted. Can transmit 20 times the bandwidth of PCS.
Country Code - For those countries not part of the North American Number Plan (NANP) - a code used to dial those countries by dialing 011 + country code + city code + number.
Cross Connect - The connection of one circuit path to another through a physical wire.
Customer Premises Equipment (CPE) - All telecommunications devices (expect pay phones) and wiring that is located at the user's location.
Cut Over - Changing from one type of equipment to another; if you install a new PBX, when you disconnect your old system and begin using the new one - you've "cut over" to the new system.