Telecommunications glossary

We’ve collected a list of definitions for common terms in the telecom industry.

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Access Charges
The fees long distance companies and other network users pay to local telephone companies to originate and terminate calls on their networks.
Access Line
A communications facility extending from a customer’s premises to a serving central office switch, sometimes referred to as a subscriber loop, local loop, or the “last mile.”
Four-digit identifier of a second service provider associated with a telephone number or thousand block.
Administrative Operating Company Number. A company that has access to update Telecom Routing Administration (TRA) databases, specifically the Business Input Routing and Rating Database System (BIRRDS).
Alliance for Telecommunications Industry Solutions
Average Schedule Companies
NECA members that receive pool revenues, or settlements, for interstate telecommunications services based on a series of statistical formulas, approved by the FCC, that approximate the amounts received by a similar cost company.
BIRRDS is the iconectiv (Telcordia) Business Integrated Routing and Rating Database System. Service Providers (SPs) and/or their agents enter their information into BIRRDS which is the information source for the Local Exchange Routing Guide (LERG).
A Bell Operating Company before the 1984 AT&T divestiture.
Call Placement Service
A service used to relay PASSporT Identity tokens to terminating service providers across the internet, out of band, in STIR/SHAKEN.
Certificate Authority
Also Certification Authority, an organization approved by the Policy Administrator to issue certificates to authorized Service Providers. Often referred to as an STI-CA. See STI-CA Certification Services.
Certificate Repository
Publicly-accessible web location where relying parties can retrieve public certificates issued by a Certificate Authority to verify signed calls in the STIR/SHAKEN framework. Sometimes referrred to as a STI-CR.
Custom Local Area Signaling Services features, such as Caller ID and call filtering.
Competitive Local Exchange Carrier. An entrant to a market where there is already an incumbent LEC providing local phone service.
Common Language Location Identifier – identifies a switch in the Public Switched Telephone Network (PSTN).
Caller ID with name.
Central Office Codes (NXX) Assignment Guidelines.
Common Line Pool
The pool NECA administers for its local exchange carrier members’ non-traffic sensitive costs of providing interstate access associated with subscriber loop plant. Pool members apply the end user common line (EUCL) charge rate element and others as tariffed in NECA’s FCC Tariff No. 5.
Cost Companies
NECA members that receive pool revenues, or settlements, for interstate telecommunications services based on their actual interstate investment and expenses, calculated each year from detailed cost studies.
Canadian Radio-television and Telecommunications Commission. The Canadian regulator for the broadcasting and telecommunications operators in Canada.
Shorthand for the NPA-NXX-X telephone numbering system.
Digital subscriber line (DSL)
A technology that brings high-bandwidth information services to the home or small business over telephone loop plant. DSL technology enables a loop to simultaneously carry voice, which takes little bandwidth, and high speed data.
DPC (Destination Point Code)
An address of a device on the Common Channel Signaling (SS7) network. The DPCs shown in the NPAC data refer to addresses components such as the databases used in the provision of Collect/Third Party Billing and Calling Name Delivery services and central office switches, for which the address is needed to facilitate inter-switch voice mail system operation (used to route the Call Waiting indicator signal from the voice mail system to the called parties serving the switch) and to accommodate AutoRecall/Auto-Call Return services.
A local area network technology that connects computers, printers, servers, etc., in a physical location. Carrier ethernet equipment provides reliable ethernet connectivity beyond the LAN through the telecommunications network. Ethernet uses twisted pair (copper), fiber optic, and coaxial cable and may also use wireless connectivity or transport.
FCC (Federal Communications Commission)
U.S. government entity endowed with the responsibility to direct the U.S. national telecommunications regulatory environment.
Firm Order Confirmation from a wireline service provider. It is the verification/acknowledgment from one Service Provider (SP) to another of receipt of a valid Service Request. (The service request is an LSR if from wireline carrier; a WPR if from a wireless carrier.)
FCC Registration Number: A unique registration number that identifies any party registered to do business with the FCC.
Governance Authority
An organization that defines the rules governing the certificate management infrastructure to ensure effective use and security of SHAKEN certificates. Often referred to as the STI-GA. Selects a Policy Administrator to run the program.

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High Cost loop (HCL) support
This Federal USF fund provides support to offset high unseparated local loop costs for rural study areas.
Interstate Common Line Support. This USF fund supports the interstate common line costs of rate-ofreturn ILECs by funding the residual between the ILEC’s interstate common line costs or revenue requirement and the revenue collected from the common line rate elements charged pursuant to NECA’s FCC Tariff No. 5.
Incumbent Local Exchange Carrier. The local telephone carrier that served an area prior to the market being opened to competition.
Industry Numbering Committee of ATIS.
Intercarrier compensation
Flows of payments among telecommunications carriers that result from the interconnection of telecommunications networks under current systems of regulation.
Internet Protocol. The method by which packet data is sent from one computer to another. Every server, router, and switch in an IP network is uniquely identified by at least one IP address.
Internet Service Provider. Business entity that provides internet service to the end user customer.
Interactive Voice Response. Technology that enables a person to interact with a computer over a phone call using voice commands or touch tone responses.
Inter-Exchange Carrier. Telephone company that provides connections between local exchanges in different geographic areas. IXCs provide inter LATA service as described in the Telecommunications Act of 1996. They're commonly referred to as “long-distance carriers.”
The four-digit identifier of the last service provider associated with the telephone number. It identifies the last reseller in the service provider chain, i.e., the one that has the retail sales relationship with the consumer.
Local Access Transport Area. The geographic region beyond which a former BOC, and certain independent LECs, cannot transport a call without involving an IXC.
Local Exchange Carrier. Local telephone company.
Local Exchange Routing Guide. A database used for the routing of calls by service providers. Provides information at the NPA-NXX and block level. Managed by the Telecom Routing Administration, an organization within iconective.
Line Information Database used by telephone companies to store and retrieve Caller ID records. Local phone switches, also known as Class 5 switches, use SS7 signaling protocol to query these centralized databases and pass this information during call set up.
Letter of Authorization required by NPAC as evidence that a carrier will allow its telephone numbers to ported to another service provider.
Local Number Portability. The ability to transfer an existing telephone number assigned by a local exchange carrier (LEC) and reassign it to another carrier.
Local Switching Support. This USF fund supports high local switching costs of small ILECs. LRN (Location Routing Number): A 10-digit number used to uniquely identify a switch that has ported or pooled numbers. The first six digits of the LRN is a valid NPA-NXX assigned to the switch that is serving the ported or pooled number. An LNP-enabled switch interrupts processing of an originating call to determine whether the called number is ported and to obtain the called number’s LRN if the number is ported (or pooled). Calls to a non-ported number are routed based on the NPA-NXX of the called number. Calls to a ported or pooled number are routed instead based on the NPA-NXX of the number’s associated LRN.
Local Service Management System. The system used to receive information from the NPAC SMS and is the Communications Service Provider’s database containing all information required for correct call routing when a customer changes from one communications service provider to another.
Local Service Request. The service request to port a number from one service provider to another. (LSR if sent from a wireline carrier; WPR if sent from a wireless carrier).
Minutes of Use
A total of all premium and non-premium originating and terminating interstate traffic sensitive switched access minutes which are switched in a Class 5 (local) end office.
N-minus-1. The next-to-last network involved in a particular call. In the case of an inter-LATA toll call, for example, the next to last network is the IXC network.The determination of the destination network (and switch) for a ported number is expected to be performed before the call is delivered to the network containing the switch serving the called number. If not already performed, the determination is made by the N-1 network.
The North American Numbering Plan. A telephone numbering plan that encompasses 25 distinct regions in twenty countries primarily in North America, including the Caribbean and the U.S. territories.
North American Numbering Plan Administrator. The entity selected by the FCC to administer the NANP.
National Exchange Carrier Association. Membership association of U.S. local telecommunications companies.
Number Plan Area. The first three digits of the 10-digit NANP telephone number.
National Number Pooling Administrator
Number Portability Administration Center. A function of the Federal Communications Commission (FCC) in the United States. It administers the routing of telephone calls and text messages (SMS) for the telecommunications industry and facilitates local number portability.
Number Portability Administration Center Service Provider Identification Number. A four-digit alpha-numeric value that identifies the owner of a record in the NPAC/SMS.
Number Portability Administration Center Service Management System. The system used by the NPAC to manage number portability processes and information. The term “NPAC/SMS” is used to refer specifically just to the NPAC hardware/software.
The first six digits of a NANP telephone number (or of an LRN).
The NPA-NXX-X represents a pooled thousand block drawn from the NPA-NXX.
Numbering Resource Utilization Forecast. NXX term used typically to represent the 4th–6th digits of the ten-digit telphone number (N = any digit 2–9, X = any digit 0–9).

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Operating Company Number. Assigned by the NECA and used as an identifier for inter-carrier transactions. The OCN of a service provider is used as its NPAC SPID.
Out-of-Band STIR
A method of sending the PASSporT Identity token to the terminating service provider’s Call Placement Service across the internet for STIR/SHAKEN processing. Details are available in our Out-of-Band STIR whitepaper.
Persona Assertion Token, which includes a number of claims the signer of the token is asserting. Used in STIR/SHAKEN to carry information about caller ID authentication.
Phantom traffic
Traffic that is terminated but is not billable because the originating source is not identified.
Point of Interconnection. Place where two telephone networks interconnect.
Policy Administrator
A trusted organization authorized by a governance authority to approve Certificate Authorities to issue certificates to Service Providers, who use them for signing calls using STIR/SHAKEN. Often referred to as the STI-PA.
Point of Presence. Place where a telephone network is available for interconnection.
Public Safety Access Point. Call center for answering calls to an emergency telephone number for police, firefighting, and ambulance services.
Public Service Commission. A state-level agency that regulates telephone companies.
Pseudo LRN
An LRN with a value of 000-000-0000. Used to indicate that the number should be routed on dialed digits; that is, it is an instruction, not a route choice.
Public Switched Telephone Network. The world’s circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication.
Public Utility Commision. State-level agency that regulates telephone companies.
Regional Bell Operating Company. In 1984, AT&T was broken up by the US Justice department. AT&T then provided long distance services and seven Regional Bell Operating Companies provided local telephone service. The original RBOCs were Ameritech, Bell Atlantic, BellSouth, Nynex, PacTel, SouthWestern Bell and US New Vector. As of 2019, the remants of the seven RBOCs have been consolidated into AT&T, Verizon and CenturyLink.
Rich Call Data
Additional information about the caller, such as caller name and logo image, that can be added to the SHAKEN Identity header to help persuade the called party to answer the call. This is especially attractive to enterprises that wish to place their calls with a consistent brand presentation. For more information, see our whitepaper on Rich Call Data and STIR/SHAKEN.
Service Control Point. Transaction processor-based system that provides common channel signaling network interface to database services.
A settlement is calculated for each pooling company based on their individual expense and tax amounts, including a share of the pool’s calculated rate of return. Each company then receives its settlement minus the access revenue it has already collected.
Switch Homing Arrangement. Homing arrangements include such situations as mapping, to a switch, any appropriate Feature Group B, C, and/or D tandems; STPs; in the case of remotes, their Hosts; in the case of Points of Interfaces (POIs), their ACTUAL SWITCH; etc. This information is defined in LERG7SHA.
Service Provider Identification Number. (See NPAC SPID.)
Signaling System 7. An internationally standardized, general-purpose Common Channel Signaling protocol. It defines the signalingbackbone for the public switched telephone network.
Service Switching Point or service switch point. A switching office that has the SSP features, enabling interactions with SCPs.
Secure Telephone Identity. Methods and technology frameworks used to authenticate and verify caller ID. Often used in reference to STIR/SHAKEN.
Signal Transfer Point. A Signaling point in the Common Channel Signaling network with the function of transferring signaling messages from one signaling link to another. A packet switch that transmits messages between switches and other network components. Also transmits messages between switches in the process of normal call set-up and routing. Its function is analogous to a tandem switch in the PSTN.
Tariff 4
NECA’s F.C.C. Tariff No. 4 describes the location and technical capabilities of wire centers providing interstate access telecommunications service. It also provides information to support the ordering and billing of jointly provided (meet point or billing percent) interstate access service. Tariff 5 NECA’s F.C.C. Tariff No. 5 contains the rates, regulations, service terms and conditions that apply to interstate access services offered by local member telephone companies participating in the tariff.
Thousands-Block Number (NXX-X) Pooling Administration Guidelines.
Transaction Capabilities Application Part. TCAP is the application layer of the Transaction Capabilities protocol that is used for messages between end offices and remote databases. (The switch uses TCAP messages over the Common Channel Signaling network to query its LNP call routing database, but uses ISUP messages over the CCS network to set up voice paths to other switches.)
Telephone Consumer Protection Act of 1991. This law restricts telemarketing activities, established the Do Not Call Registry and created the legal basis for telephone subscribers to sue callers who violate the provisions of this law.
Telecommunications Relay Services. The interstate telecommunications Relay Service Fund, established by the FCC on July 26, 1993, helps speech and hearing impaired individuals use telecom services.
Traffic Sensitive Pool. The pool NECA administers for the portion of the network where costs vary according to usage. Pool members apply the TS tariff rate elements: Traffic Sensitive – Switched, including charges to interexchange carriers (IXCs) for long distance traffic and Traffic Sensitive – Special Access, including DSL and other broadband services.

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Universal Service Fund. A group of federal funding programs that promote universal service goals created by the FCC to provide support for high cost telcos, low income consumers, rural health care initiatives, and schools and libraries.
Voice over Internet Protocol. A technology that allows users to make telephone calls using a broadband Internet connection instead of a regular (or analog) phone line.

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