Glossary of Telecom Terms : C

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Cable Entrance Facility
The entrance area in a central office for all types of outside plant cables that carry subscriber lines and interoffice transmission facilities.

See Carrier Access Billing System.

See Customer Access Line Charge.

Call Allowance Category Indicator
A code that identifies the categories of call allowances that are eligible for credit.

Call Duration Seconds Indicator
The elapsed seconds of an itemized call.

Call Region ID Indicator
The geographic name that identifies the region of calling plan usage.

Called from City Indicator
The city, town, borough or village from which a call originated.

Called from State Indicator
The state from which a call originated.

Called from Telephone Number Indicator
The number of the telephone from which a call originated.

Called to City Indicator
The city, town, borough or village in which a call terminated.

Called to Telephone Number Indicator
The number of the telephone to which a call terminated.

Calling Party Number (CPN)
The number transmitted through the network that identifies the calling party. Technically, a Common Channel Inter-office Signaling (CCIS) parameter that refers to the number transmitted on an out-of-band basis through the SS7 signaling network identifying the calling party's telephone number. Also known as Automatic Number Identification (ANI).

See Central Automatic Message Accounting.

Campus Area Network (CAN)
A network that provides interconnection in a confined geographic area such as a campus or industrial park. Such networks operate over fairly short distances, and do not require public rights-of-way.

See Campus Area Network.

Cannot Be Called
End user cannot receive phone calls.

Cancel Pre-Order Appointment Scheduling Inquiry
A Verizon Local Pre-Order transaction that allows CLECs to cancel a reserved due date. Learn more.

Cancel Pre-Order Reservation Inquiry
A Verizon Local Pre-Order transaction that allows CLECs to cancel an entire Pre-Order transaction. Consequently, any due date or telephone number(s) reserved under the initial Pre-Order transaction will be canceled. Learn more.

Cancel Pre-Order Telephone Reservation Inquiry
A Verizon Local Pre-Order transaction that allows CLECs to cancel any or all reserved telephone number(s). Learn more.

See Competitive Access Provider.

Caption Listing
A package of directory listings for an end user with multiple listings under the same name.

See Customer Account Record Exchange.

Carrier Access Billing System (CABS)
System for billing Interexchange Carriers and other service providers for access to the Verizon network.

Carrier Account Team Center (CATC)
Verizon Center that cares for provisioning and maintenance of special access services in the Verizon East region.

Carrier Identification Code (CIC)
A unique three- or four-digit access identification code that is assigned by Telcordia Technologies for use with certain switched access services. The CIC identifies the caller's long distance carrier.

Carrier Identification Parameter (CIP)
A service that allows carriers to consolidate trunk groups by identifying traffic generated by multiple Carrier Identification Codes (CIC) onto a single trunk group. Learn more.

Carrier Working Group (CWG)
An Industry Forum that is chaired rotationally by CLECs and ILECs; its charge is to provide guidelines for carrier-to-carrier performance metrics in the state of New York.

Casual Usage
Usage dialed using a calling card or by dialing the prefix, 1010XXX.

See Cannot Be Called.

Can't Break Dial Tone. The end user cannot break dial tone to call out.

See Constant Bit Rate.

See Common Channel Inter-office Signaling (CCIS).

See Customer Carrier Name Abbreviation.

Can't Call Out. The end user can receive calls but cannot call out.

See Common Channel Signaling or Hundred Call Seconds.

See Common Channel Signaling Access Connection.

See Common Channel Signaling Network.

See Common Channel Signaling System 7.

See Copper Distributed Data Interface.


  1. Unit of data packet transmission.
  2. A geographical unit with mobile telephone system transmission channels assigned to a particular mobile (wireless) telephone service provider.

Cell Relay
Network transmission format that uses small data packets of the same size, called cells. The cells are fixed length, and can be transmitted at very high rates.

Cell Relay Service
A carrier service that supports the receipt and transmission of ATM cells between end users in compliance with ATM standards and implementation specifications.

Cell Transfer Delay (CTD)
ATM performance parameter that specifies the average transit delay of cells between a source and destination over a given virtual circuit.

Cellular Telephone System
A high-capacity land-based mobile (also known as wireless) telephone system wherein channels assigned to the system are divided among several geographical cells covering a defined service area. A cellular system is capable of reusing the same channels in different cells within the service area. Use of many small cells with low transmitter powers permits intensive reuse of channels in a given area, thereby increasing system capacity.

Central Automatic Message Accounting (CAMA)
A process using centrally located equipment, associated with a tandem or a toll switching office, for automatically recording billing data for end-user customer dialed calls originating from several local central offices.

Central Office (CO)
Verizon building where end users' lines are joined to switching equipment that connects other end users to each other, both locally and via long distance carriers. The central office contains the associated inside plant network elements required to perform this function, such as distribution frames, interoffice facility termination points, and so on. Also known as End Office and Entity.

Central Office Code, CO Code, NXX, NXX Code
The three digit switch entity indicator which is defined by the D, E, and F digits of a 10-digit telephone number. Each NXX code contains 10,000 station numbers. Historically, entire NXX code blocks have been assigned to specific individual local exchange end office switches.

Central Office Distribution Frame
The primary point at which outside plant facilities terminate within a wire center for interconnection to other telecommunications facilities within the wire center. Also known as Main Distribution Frame (MDF).

Central Office Prefix
The first three digits (NXX) of a seven-digit telephone number under which up to 10,000 telephone numbers are grouped; exchange area boundaries are associated with the central office code. Several central office codes may be served by a single central office switching system.

Central Office Switch (or Switch)
Often referred to as the switch, the telephone company facility that connects subscribers to each other, locally and long distance. CO switches include the following:

  • End Office Switches, Class 5 switches from which end-user Exchange Services are directly connected and offered
  • Tandem Office Switches, Class 4 switches that are used to connect and switch trunk circuits between and among central office switches

NOTE: Central office switches may be employed as combination end office switch/tandem office switches (combination Class 5/Class 4).

Centralized Message Distribution System (CMDS)
The billing record and clearing house transport system used by Verizon and other ILECs used to exchange collection data and Carrier Access Billing System (CABS) records.

A class of central office service that provides the equivalent of PBX service from a telephone company switching system. Permits station-to-station dialing, direct inward dialing to a particular station, and station identification on outgoing calls.

Certificate of Public Convenience and Necessity (CPCN)
A document that registers a company as a carrier with the Commissions in the states where it provides service. Process/requirements may differ by state.

Change Management Process
The process by which Verizon and Telecommunications Companies (TCs) work together to implement changes to OSS interfaces, associated business rules, and applicable business processes and applies throughout the region served by Verizon.

An electrical or photonic (for fiber optic-based systems) communication path between two or more points of termination.

Channel Service Unit (CSU)
Equipment that performs one or more of the following functions: termination of a digital facility; regeneration of digital signals; detection and/or correction of signal format error; and remote loopback.

See Carrier Identification Code.

See Customer Identification Number.

See Committed Information Rate.

A two-way communication path.

Circuit Code
The specific Interexchange Carrier trunk group that is required to carry the call for SS7 messages.

Circuit Emulation
A connection over a virtual circuit-based network that provides service to end users that is indistinguishable from a real, point-to-point, fixed-bandwidth circuit.

See Customer Inquiry Response Team.

See Circuit Facility Assignment.

Circuit Facility Assignment (CFA)
Allows Wholesale Access customers to validate the DS1/DS3 at system and channel Levels.

Circuit Switching
Switching system in which a dedicated physical circuit path exists between sender and receiver for the duration of the call. Used heavily in service provider company networks, circuit switching is often contrasted with contention and token passing as a channel-access method, and with message switching and packet switching as a switching technique. Learn more at Verizon East, and Verizon West.

A report to Verizon that describes what the customer believes to be an incorrect charge. Claims may be made for recurring charges, non-recurring charges and usage; they may be general or individual.

Claims Input File
A file format through which claims are submitted electronically to Verizon.


See Custom Local Area Signaling Services.

Class Features
CCS-based features available to end users; for example, Automatic Call Back, Call Trace, Caller Identification, and Call Return.

Class of Exchange or Class of Office
Ranking assigned to a switching point in the telephone network that is determined by its switching functions, interrelationships with other exchanges, and transmission requirements.

See Competitive Local Exchange Carrier.

Call set-up between CLEC Service Switching Points (SSPs).

CLEC Electronic Utilization Report
A report generated monthly indicating a CLEC/Reseller's utilization of LSI-TA application.

CLEC/Reseller Application
An application built or purchased by a CLEC or Reseller to interface with Verizon through Verizon OSS Gateways. Such an application can process Pre-Order, Local Service Requests (LSR) and/or Access Service Request (ASR) transactions.

CLEC Loop Provisioning Center (CLPC)
Verizon Center that oversees the provisioning of new digital loops and line sharing requests.

CLEC Performance Measures
Monthly Performance Measurement reports provided by Verizon to CLECs/ Resellers on-line. The reports currently available are Verizon West (former GTE), Verizon East (former Bell Atlantic), and Verizon West FCC measures. Learn more.

CLEC Test Environment
Verizon-provided environments for the testing of application-to-application interfaces for local pre-order and order transactions. Learn more.

See Common Language Location Identifier.

11-character code that identifies the wire center from which a call originated.

See CLEC Loop Provisioning Center.

Any of the sources of timing signals used in data transmission.

Closed End
The end of a switched access service that receives ringing and dial tone, and transmits address signals.

See Centralized Message Distribution System.

C-Message Noise
The frequency-weighted, short-term average noise within an idle channel. Frequency weighting, called C-message, is used to account for the variations in 500-type telephone set transducer efficiency and end user annoyance to tones as a function of frequency.

C-Message Weighting
A noise measurement factor.

See Commercial Mobile Radio Service.

See Connectivity Management Team.

See Confirmation Notice Form.

See Complementary Network Services.

C-Notched Noise
The C-message frequency-weighted noise on a channel with a holding tone that is removed at the measuring end through a notch (very narrow band) filter.

See Central Office.

The Customer Ordering Assistant Tool (COAT) helps you place service requests for IntelliLight Broadband Transport, Custom Connect, and DS3 (Special) Service. This easy-to-use tool provides the appropriate ASR entries for fields such as: NC - Network Channel, NCI - Network Channel Interface, SEC NCI - Secondary Network Channel Interface, SPEC - Service and Product Enhancement Code, SR - Special Routing, and VTA - Variable Term Agreement.

CO Code, Central Office Code, NXX, NXX Code
The three-digit switch entity indicator which is defined by the "D", "E", and "F" digits of a 10-digit telephone number within the North American Numbering Plan. Each NXX code contains 10,000 station numbers. Historically, entire NXX code blocks have been assigned to specific individual local exchange end office switches.

Coaxial Cable
A transmission line in which one conductor is a wire at the center of the cable; the other conductor surrounds the center wire with a layer of insulating material between them. Coaxial cable can transmit greater bandwidth than twisted pair (TP) wires.

Coin Line Port
A Verizon Wholesale UNE offering that enables public telephone services. Learn more.

Collapsed Backbone
A non-distributed backbone in which all network segments are interconnected via an internetworking device. A collapsed backbone may be a virtual network segment that exists in a device such as a hub, a router, or a switch.

Collocated Interconnection Equipment
The telecommunications cable and equipment owned/leased and installed by the Collocator for the sole use of the Collocator in connection with equipment installed within its Collocated Interconnection Space.

Collocated Interconnection Space
Space suitable for occupancy by Collocated Equipment used for telecommunications operations, along with the work area required to maintain that equipment.

An arrangement whereby the facilities of one party (the Collocating Party) are terminated with the equipment necessary to provide interconnection or access to the network elements offered by the second Party. This equipment is installed and maintained at the premises of the second Party (the Housing Party). All such services and facilities used for Collocated Interconnection are for carriage of non-switched interstate traffic. For purposes of Collocation, the premises of a Housing Party are described as a Housing Party Wire Center, other mutually agreed-upon locations of the Housing Party, or any other location for which Collocation has been ordered by the FCC or the state Commission. Verizon provides Collocation housing under terms, rates, and conditions as described in tariffs filed with the FCC and Commissions.

Collocation may be physical or virtual. For physical collocation, the Collocating Party installs and maintains its own equipment in the Housing Party's premises. For virtual collocation, the Housing Party owns, installs, and maintains equipment that is purchased by the Collocating Party, located in the Housing Party's premises, and dedicated to use by the Collocating Party. Learn more.

Collocation Assignment Validation
A Verizon local pre-order transaction that allows the CLECs to validate UNE loops and splitters for collocation assignments terminating in a wire center, excluding the connecting facility assignment and sub loop arrangements. Learn more.

Collocation Facility Assignment Inquiry
A Verizon local pre-order transaction that provides a CLEC with the collocation assignment information. The condition of the existing facility(s) will be identified as assembled in the field. Learn more.

Collocation: Physical
A Verizon Wholesale service offering that allows CLECs to occupy dedicated space within a central office; Verizon then provides points of interconnection between a CLEC's equipment and the Verizon network. Learn more.

Collocation: Virtual
An alternative to physical collocation; a CLEC owns equipment in a Verizon Central office and leases it back to Verizon; Verizon installs and maintains the equipment, either directly or through a third party. Learn more.

A Verizon customer that subscribes to Collocation.

Commercial Mobile Radio Service (CMRS)
A radio communication service between mobile stations or receivers and land stations, or by mobile stations communicating among themselves, that is provided for profit, and that makes interconnected service available to the public.

Commercial Mobile Radio Service (CMRS) Provider
A telecommunication common carrier, authorized by the Federal Communications Commission (FCC), that uses radio as the principal means of connecting its end-user subscribers with the Public Switched Telephone Network (PSTN).

Commission (or State Commission, or Public Service Commission)
Any applicable state regulatory body having jurisdiction over telecommunications carriers.

Committed Information Rate (CIR)
The specified transport speed that a frame relay network will maintain between service locations.

Common Carrier
A telecommunications company that provides communication transmission services, such as telephone and telegraph, to the public. The local telephone service provider is an example of a common carrier.

Common Channel Inter-office Signaling (CCIS)
A transmitting method for network facilities that carry the actual voice or data traffic of the call.

Common Channel Signaling (CCS)
High-speed specialized packet-switched communications that is separate (out-of-band) from the public packet-switched and message networks; protocol used on the CCS/SS7 network.

Common Channel Signaling Access Connection (CCSAC)
Connection of one party's signaling point of interconnection to the other party's signal transfer point for the exchange of SS7 messages.

Common Channel Signaling Network (CCSN)
A high-speed specialized packet-switched communications network that is separate (out-of-band) from the public packet-switched and message networks. Carries addressed signaling messages for individual trunk circuits and/or database-related services. The network was developed by the Consultative Committee for International Telephone and Telegraph (CCITT) and the American National Standards Institute (ANSI).

Common Channel Signaling System 7 (CCS/SS7)
CCS/SS7 carries addressed signaling messages for individual trunk circuits and/or database-related services between signaling points in the CCS network using the SS7 signaling protocol.

Common Language Location Identifier (CLLI)
11-character code that identifies the wire center from which a call originated.

Common Line
A line, trunk, pay telephone line, or other facility provided under the local general service tariffs of the ILEC, terminated on a central office switch.
A common line-residence is a line or trunk provided under the residence regulations of the local general services tariffs.
A common line-business is a line provided under the business regulations of the local general services tariffs.

Communications Trouble and Analysis Center (CTAC)
A Verizon center that provides a single point of contact for wholesale customers. The CTAC is the administrative center for monitoring and dispatching trouble calls, and for resolving usage, billing and connectivity issues.

Company Code
A four-character code assigned by the National Exchange Carrier Association (NECA) that identifies CLECs and Resellers.

Company User Administrator (CUA)
An individual named user of Verizon Wholesale web-based applications who assumes, for his or her company, responsibility for approving requests for user names and passwords, changing/updating user record data and deleting obsolete usernames and passwords. Learn more.

Competitive Access Provider (CAP)
Common carriers that provide local service. These companies compete with local telephone service providers to provide access services that connect end-users to long distance companies (Interexchange Carriers).

Competitive Local Exchange Carrier (CLEC)
Any company or person authorized to provide local exchange services in competition with an ILEC. A CLEC provides similar or identical telecommunications services to the ILEC.

Complementary Network Services (CNSs)
Basic services associated with an end user's lines that make it easier for Enhanced Service Providers to offer their services.

A mechanism for allocating very large amounts of bandwidth for transport of a payload associated with a 'superrate service', which is a service at a transmission rate greater than the normal maximum rate of OC-1. The set of bits in the payload is treated as a single entity, as opposed to being treated as separate bits or bytes or time slots. The payload, therefore, is accepted, multiplexed, switched, transported and delivered as a single, contiguous chunk of payload data.

The adjustment of the electrical characteristics of transmission lines to improve their performance for specific uses. Conditioning involves the tuning of the line or addition/deletion of equipment to improve its transmission characteristics.

Confirmation Notice Form (CN)
The form that provides the customer with information associated with an order for service.

Excessive network traffic.

Congestion Control
Network management effort to control traffic flow so that switches and end-stations are not overwhelmed with information because of excessive network traffic.

A direct electronic method of delivering CLEC and Reseller usage data files and Reseller bills, and transmitting CLEC ASRs. Available in several platforms including NDM-MVS for mainframe and NDM-PC for personal computers. Also known as Network Data Mover (NDM).

Connecting Facility Assignment (CFA)
Identification of a channel or frame of a high-capacity facility that will be used by a customer.

The electronic method of connecting to Verizon's ordering and trouble administration systems.

Connectivity Guide
The source of information that will assist users in choosing the appropriate connectivity option. Learn more.

Connectivity Management Team
A Verizon Wholesale department that enables Wholesale customers to establish the ability to transmit and receive electronic messages to and from Verizon.

Constant Bit Rate (CBR)
Delay-intensive applications such as video and voice, that must be digitized and represented by a continuous bit stream. CBR traffic requires guaranteed levels of service and throughput.

Conventional Signaling
The inter-machine signaling system that has been traditionally used in North America for the purpose of transmitting the called number's address digits (telephone number) from the originating end office to the switching machine that will terminate the call. In this system, all dialed digits are received by the originating switching machine, a path is selected, and the sequence of supervisory signals and outpulsed digits is initiated. No overlap outpulsing, ten-digit Automatic Number Identification (ANI), information digits, or acknowledgment wink are included in this signaling sequence.

Copper Distributed Data Interface (CDDI)
A version of FDDI that runs on copper twisted-pair wires, rather than on fiber.

See Certificate of Public Convenience and Necessity.

See Customer Premise Equipment.

See Calling Party Number.

See Customer Profile Self-Service Tool.

See Customer Record Information System.

Cross Connection
A connection provided to a Collocator at the digital system cross connect, main distribution frame or other frame or panel between the CLEC's equipment and equipment or facilities owned by Verizon.

See Customer Service Administrator/Attendant.

See Customer Service Management.

See Customer Service Record.

See Channel Service Unit.

See Communications Trouble and Analysis Center.

See Cell Transfer Delay.

See CLEC Test Environment.

See Customized User Billing Interface System.

See Customer User Forum.

Custom Local Area Signaling Services (CLASS)
A generic term describing several local service offerings such as incoming-call identification, call trace, call blocking, automatic return of the most recent incoming call, automatic re-dial, selective call forwarding, etc.

An individual, partnership, association, joint stock company, trust, corporation or governmental entity that subscribes to telecommunications services offered by Verizon or a CLEC or Reseller.

Customer Access Line Charge (CALC)
Basic rates paid for lines from customer premises to a central office.

Customer Account Record Exchange (CARE)
ATIS industry standard for formatting exchange of subscription information.

Customer Billing Services System
Billing system for local wholesale billing in Verizon West.  Learn more.

Customer Carrier Name Abbreviation (CCNA)
A three character code that identifies the common language IAC code for a customer submitting an ASR or LSR. See Business Rules for more information.

Customer Code (Cus Code)
A new Customer Code is assigned to distinguish a converted CLEC sub-account from the old Verizon end user account.

Customer Identification Number (CIN)
A unique number that identifies a customer. Also known as Master Customer Number (MCN).

Customer Inquiry Response Team (CIRT)
The point of contact for CLECs regarding local service requests and associated forms. CIRT also assists CLECs with finding the information they need on the Wholesale Web site and with reading Customer Services Records (CSRs). Learn more.

Customer Premise Equipment (CPE)
Telephone terminating equipment, such as handsets, PBXs, and modems located on the customer's premises and connected to the phone service provider network.

Customer Profile Self Service Tool (CPSST)
A Verizon tool that provides CLECs/Resellers the ability to submit Local Services Profile specific data to Verizon through self-service. Learn more.

Customer Record Information System (CRIS)
A Verizon database containing end user information used for billing.

Customer Service Administrator/Attendant (CSA)
Verizon customer support employee.

Customer Service Inquiry
A Verizon local pre-order transaction that provides access to the Verizon data for the purpose of determining existing services for a specified end user.  Learn more.

Customer Service Management (CSM)
A Verizon Wholesale Solution that provides customers with real time information about the operational status of their Dedicated SONET Ring networks. Learn more.

Customer Service Record (CSR)
A record containing customer specific information on end user's account. The CSR contains Listing, Billing and Service and Equipment sections detailing the type of listing(s) for the account, as well as a breakdown of the lines and features.

Customer Service Record Information
A Verizon Wholesale local pre-order transaction that allows access to the end-user's CSR data.

Customized User Billing Interface System (CUBIS)
A system that allows Interexchange Carriers to monitor and update subscriber service orders. This assists in maintaining an accurate end-user database for billing purposes.

Customer User Forum (CUF)
Joint CLEC and Verizon Forum that provides a vehicle to review, and resolve generic operational issues specific to ordering, provisioning and maintenance (NMC, RCCC, RCMC, CATC, etc) that collectively impact multiple CLECs. CUF is not designed to replace the day to-day operational interfaces.

Customer Wholesale Portal (CWP) Reports
A group of reports that provide local service providers (LSPs) with information to facilitate pre-order and order processing. Learn more.

Physical changing of lines from one system to another, usually at the time of a new system installation.

See Customer Wholesale Portal (CWP) Reports.



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