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.”
Alt SPID
Four-digit identifier of a second service provider associated with a telephone number or thousand block.
AOCN
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).
ATIS
Alliance for Telecommunications Industry Solutions www.atis.org
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
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).
BOC
A Bell Operating Company before the 1984 AT&T divestiture.
CLASS
Custom Local Area Signaling Services features, such as Caller ID and call filtering.
CLEC
Competitive Local Exchange Carrier. Anentrant to a market where there is already an incumbent LEC providing local phone service.
CLLI
Common Language Location Identifier – identifies a switch in the Public Switched Telephone Network (PSTN).
CNAM
Caller ID with name.
COCAG
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.
CRTC
Canadian Radio-television and Telecommunications Commission. The Canadian regulator for the broadcasting and telecommunications operators in Canada. www.crtc.ca
Dash-X
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.
Ethernet
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. www.fcc.gov
FOC
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.)
FRN
FCC Registration Number: A unique registration number that identifies any party registered to do business with the FCC.

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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.
ICLS
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.
ILEC
Incumbent Local Exchange Carrier. The local telephone carrier that served an area prior to the market being opened to competition.
INC
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.
IP
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.
ISP
Internet Service Provider. Business entity that provides internet service to the end user customer.
IVR
Interactive Voice Response. Technology that enables a person to interact with a computer over a phone call using voice commands or touch tone responses.
IXC
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.”
Last-Alt-SPID
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.
LATA
Local Access Transport Area. The geographic region beyond which a former BOC, and certain independent LECs, cannot transport a call without involving an IXC.
LEC
Local Exchange Carrier. Local telephone company.
LERG
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.
LIDB
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.
LOA
Letter of Authorization required by NPAC as evidence that a carrier will allow its telephone numbers to ported to another service provider.
LNP
Local Number Portability. The ability to transfer an existing telephone number assigned by a local exchange carrier (LEC) and reassign it to another carrier.
LSS
Local Switching Support. This USF fund supports high local switching costs of small ILECs. www.neca.org 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.
LSMS
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.
LSR
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-1
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.
NANP
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.
NANPA
North American Numbering Plan Administrator. The entity selected by the FCC to administer the NANP.
NECA
National Exchange Carrier Association. Membership association of U.S. local telecommunications companies.
NPA
Number Plan Area. The first three digits of the 10-digit NANP telephone number.
NPAC
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.
NPAC SPID
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.
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.
NPA-NXX
The first six digits of a NANP telephone number (or of an LRN).
NPA-NXX-X
The NPA-NXX-X represents a pooled thousand block drawn from the NPA-NXX.
NRUF
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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OCN
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.
NPA
National Number Pooling Administrator www.nationalpooling.com
Phantom traffic
Traffic that is terminated but is not billable because the originating source is not identified.
POI
Point of Interconnection. Place where two telephone networks interconnect.
POP
Point of Presence. Place where a telephone network is available for interconnection.
PSAP
Public Safety Access Point. Call center for answering calls to an emergency telephone number for police, firefighting, and ambulance services.
PSC
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.
PSTN
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.
PUC
Public Utility Commision. State-level agency that regulates telephone companies.
RBOC
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 2018, the remants of the seven RBOCs have been consolidated into AT&T, Verizon and CenturyLink.
SCP
Service Control Point. Transaction processor-based system that provides common channel signaling network interface to database services.
Settlement
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.
SHA
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.
SPID
Service Provider Identification Number. (See NPAC SPID.)
SS7
Signaling System 7. An internationally standardized, general-purpose Common Channel Signaling protocol. It defines the signalingbackbone for the public switched telephone network.
SSP
Service Switching Point or service switch point. A switching office that has the SSP features, enabling interactions with SCPs.
STP
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 www.neca.org 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.
TBPAG
Thousands-Block Number (NXX-X) Pooling Administration Guidelines.
TCAP
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.)
TRS
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.
TSP
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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USF
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.
VoIP
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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