NPAC Knowledgebase


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Alt SPID: The four-digit identifier of a second service provider associated with a telephone number or thousand block.  It identifies the wholesale service provider customer to which the PSTN service provider has assigned the number. The second service provider in turn may either assign the number to its retail customer or to another service provider for its use.

ASN1: Abstract Syntax Notation One

ATIS: Alliance for Telecommunications Industry Solutions

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Block ("thousand block"): A group of 1,000 contiguous telephone numbers in the range NPA-NXX-X000 through NPA-NXX-X999. Usually referred to as a "pooled bock" even when not actually assigned by the nation number pooling administrator.

Block Available: A thousand block that is not assigned to a service provider.

Block Contaminated: A thousand block that has working numbers. A block with any working numbers is contaminated, but as long as no more than 100 numbers in the block are working, the block is eligible for donation to the Pool Administrator's thousand block pool.

Block-Assignee, -Holder, -Owner: The service provider to which the thousand block has been assigned by the Pool Administrator.

BOC: A Bell Operating Company was a company owned or controlled by AT&T prior to the 1984 AT&T divestiture action.

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CLNPC (Canadian LNP Consortium Inc.): A private Canadian Corporation established to facilitate the development and provision of a Local Number Portability (LNP) system for use by Canadian Carriers.

CLASS (Custom Local Area Signaling Services): Identifies a group of vertical service features such as Caller ID (calling number delivery), Calling Name delivery, and call filtering (either to accept or to reject calls from specified numbers).  (See also DPC.)

Class 1 Interconnected VoIP: A VoIP service provider that directly interfaces with the Public Switched Telephone Network and is eligible to receive numbering resource assignments from the NANPA and PA.

Class 2 Interconnected VoIP: A VoIP service provider that relies on a PSTN provider switch for access to the Public Switched Telephone Network and for telephone numbers to assign to its customers.

Class 3 Interconnected VoIP: A reseller of Class 1 or Class 2 Interconnected VoIP provider services.

CLEC: Competitive Local Exchange Carrier. The land line carrier entrant to a market where there is already an incumbent LEC providing local phone service.

CNAM: Caller ID with name. (See also DPC.)

Code-Assignee, -Holder, -Owner: The service provider to which an NPA-NXX code is assigned by the NANPA or the Pool Administrator.

Contaminated Block: "Contamination" refers to the fact that some telephone numbers are working in a block. If the block is then assigned to another service provider, not all of the telephone numbers in the block are available to the new block-owner for its use. Before such a block is donated to the PA pool for reassignment, the current block-owner must intra-SP port the working numbers. Later, as each one of these intra-SP ported numbers is disconnected, the now-vacant telephone number is restored to the block and becomes available to the block-owner for its use.

CRTC:  Canadian Radio-television and Telecommunications Commission. The CRTC regulates and supervises the broadcasting and telecommunications systems in Canada.

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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 Auto-Recall/Auto-Call Return services.

Dash X: The Dash-X is shorthand for the NPA-NXX-X that represents the 1,000 numbers in a thousand block in the NPAC/SMS network data. Similarly, an NPA-NXX code is a network data level representation of 10,000 numbers.

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FCC (Federal Communications Commission): U.S. government entity endowed with the responsibility to direct the U.S. national telecommunications regulatory environment.

FOC: Firm Order Confirmation from a wireline service provider. It is the verification/acknowledgment from one 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.)

FRS: Functional Requirements Specifications for the NPAC/SMS.

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GDMO: Guidelines for the Definition of Managed Objects.

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IIS: Inter-Operability Interface Specifications for the NPAC/SMS.

ILEC (Incumbent Local Exchange Carrier): The local wireline service provider, either an RBOC or an Independent LEC, that served a market prior to the market being opened to competition.

INC (Industry Numbering Committee): A standing committee of the Alliance for Telecommunications Industry Solutions (ATIS) that provides an open forum to address and resolve industry-wide issues associated with planning, administration, allocation, assignment and use of the North American Numbering Plan (NANP) numbering resources within the NANP area.

ISVM: Inter-Switch Voice Mail. A centralized voice mail system. (See also DPC.)

IVR (Interactive Voice Response): The IVR is a dial-up service provided by the NPAC that is used by law enforcement agencies, public safety and 911 service providers to retrieve current service provider information.

IXC (Inter-Exchange Carrier): A carrier that provides connections between local service providers when they do not have connection arrangements appropriate for a call. In particular, used when regulatory restrictions preclude delivery of a call across LATA boundaries. A LEC also may function as an IXC.

Intermodal Porting: Porting telephone numbers between wireline and wireless service providers.

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LAN: Local Area Network. A group of client computers connected to a server.

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.

LEAP (Local Number Portability Enhanced Analytical Platform): A subscription-based, online portal which allows law enforcement agencies to retrieve information on numbers.

LEC (Local Exchange Carrier): A company that provides local wireline telephone service. 

LERG (Local Exchange Routing Guide): A database owned by Telcordia and providing information at the NPA-NXX and block level.

LIDB (Line Information Database): One of the original uses is to allow a toll operator to determine whether a telephone number may be billed for a call (Collect or Third Number) by indicating whether the billed number is a public phone. Other uses include an indication that a number will accept all Collect calls, so it is not necessary to have an operator obtain agreement from the billed party on each call. (See also DPC).

LISP: This "LNP Type" is the NPAC/SMS term for the number record resulting from an Intra-Service Provider Port. Ports between different SPIDs, even when both SPIDs represent the same service provider, are not considered by the NPAC/SMS to be intra-SP ports.

LNP (Local Number Portability): The FCC-ordered capability for a consumer to retain his number when changing service providers. Enables a consumer to keep his telephone number when he changes telecommunications service providers. The "local" refers to the limited area of portability -- the rate area associated with the telephone number cannot change as the result of a port -- not to a "local number." In other words, the first six digits of a telephone number indicate the rate area associated with the telephone number whether or not the number has been ported.

LNP Type: The NPAC/SMS database classifies porting activity into three types:

  • LNP Type 1 - LSPP - inter-service provider port - a number that has been ported between two different SPIDs
  • LNP Type 2 - LISP - intra-service provider port - a number that has been ported within the same SPID
  • LNP Type 3 - POOL - a number contained in a pooled thousand block

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 owned by a service provider and which receives data broadcast from the NPAC/SMS. The LSMS provisions the service provider's downstream systems, such as its LNP call routing database. The LSMS is a mechanized system used (primarily) to receive data broadcasts from the NPAC/SMS.

LSP (Local Service Provider): A company that provides local telephone service. The term is used to describe the service provider having the retail relationship with the consumer.

LSPP (LNP Inter-Service Provider Port): This "LNP Type" is the NPAC/SMS term for the number record resulting from an Inter-Service Provider Port. Ports between different SPIDs, even if the SPIDs represent the same service provider, are considered by the NPAC/SMS to be inter-service provider ports.

LSR: The service request to port a number, sent from one SP to another. (LSR if sent from a wireline carrier; WPR if sent from a wireless carrier).

LTI (Low-Tech Interface): A manual system used to submit data to the NPAC/SMS.

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MSA (Metropolitan Statistical Area):  A U.S. Census Bureau term.

MUMP (Mass Update Mass Porting): A method of creating, modifying, and deleting number records at the NPAC/SMS without using a service provider's NPAC/SMS interface.

Mechanized Interface: The term refers to the NPAC/SMS interface for both the LSMS that receives the data broadcasts from the NPAC/SMS and the SOA that sends data to the NPAC/SMS.

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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.

NANC (North American Numbering Council): The NANC was established by the FCC October 5, 1995 to provide advice and recommendations to the FCC and other governments (including those of Canada and the Caribbean countries) on numbering issues. NANC members include representatives from local exchange carriers [wireline carriers], interexchange carriers, wireless providers, manufacturers, state regulators, consumer groups and telecommunications associations.

NANP (North American Numbering Plan): The NANP is the plan for telephone numbers in Canada, the US and its territories, and the Caribbean. Telephone number addresses in the NANP are in the form NXX-NXX-XXXX, where N is any digit from 2-9 and X is any digit from 0-9. (The format often is expressed as NPA-NXX-XXXX to reflect the fact that the first three digits of the telephone number represent the area code.) The first six digits (NPA-NXX) of the telephone number identify the local serving switch. The NPA-NXX of a telephone number also indicates the geographic area ("rate area") associated with the number. There are exceptions to the meaning of a number's NPA-NXX, such as for "toll-free" numbers and those in certain specially designated NPA-NXXs.

NANPA (North American Numbering Plan Administrator): The entity selected by the FCC to administer the NANP.

NAPM, LLC (North American Portability Management, LLC): The private entity with which Neustar contracts to provide the NPAC services. The NAPM LLC is recognized by the FCC as representing the interests of the industry with respect to number portability. The NAPM LLC membership is limited to representatives of the service providers subject to the FCC's LNP mandates.

NNSP (New Network Service Provider): The NNSP is the service provider operating the switch to which the consumer's telephone number is moving. The NSP is the new service provider to which the consumer is moving. The two terms can represent the same entity. However, if the consumer is moving to a "reseller" then the reseller is the NSP and the PSTN switch operator is the NNSP.

NPA (Number Plan Area): The first three digits of the 10-digit NANP telephone number. An NPA is always contained within the boundaries of a single state.

NPAC (Number Portability Administration Center): The term NPAC refers to the entire operation: both personnel and equipment.

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.

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. The SPID is an NPAC account number and in most cases is drawn from the NPAC User's OCN. The SPID of the owner of a record is included in the data broadcast to the LSMSs.

NPA-NXX: The first six digits of a NANP telephone number (or of an LRN). The NPA-NXX is the PSTN address of the switch serving the telephone number. In a non-pooling area, the NPA-NXX code and the associated 10,000 numbers are assigned by the NANPA. In a pooling area, the NPA-NXX code is assigned by the Pool Administrator along with one or more thousand blocks drawn from the NPA-NXX. Other thousand blocks drawn from the NPA-NXX are assigned by the PA and can be used in switches other than the one to which the NPA-NXX itself is assigned.

NPA-NXX-X: The NPA-NXX-X represents a pooled thousand block drawn from the NPA-NXX.

NSP (New Service Provider): The NSP is the new service provider to which the consumer is moving. (See also NNSP.)

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): The OCN is assigned by The National Exchange Carrier Association, Inc. (NECA) and is used as an identifier for inter-carrier transactions. The OCN of a service provider is used as its NPAC SPID.

ONSP (Old Network Service Provider): The term used to describe the service provider from which the consumer is moving. When the consumer was served reseller, then ONSP is used to refer to the PSTN service provider used by the reseller. (See also OSP.)

OSP (Old Service Provider): The term used to describe the service provider from which the consumer is moving and with which the consumer had a retail relationship. (See also ONSP.)

OSS: Operations Support System

Open Code: The term refers to NPA-NXX codes that have been opened in the network data of the NPAC/SMS. A code must be open in the NPAC/SMS in order to allow numbers in that code to be ported or pooled. A list of open codes is provided in the public area of the NPAC web site. Note that a code may be open in NPAC solely to allow number pooling, i.e., porting may not yet be available for that code.

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PA (Pooling Administrator): The entity selected by the FCC to administer national number pooling.

PAS (Pooling Administration System): A web-based application that enables service providers to manage their numbering resources.

Pooled Block: A thousand block assigned by the national number pooling administrator. (see Block)

Pooled Block-Assignee, -Holder, -Owner: The service provider to which a thousand block is assigned by the Pool Administrator.

Pooling: Allows the assignment of numbers in blocks of 1,000 rather than requiring all 10,000 numbers to be assigned to the service provider to which an NPA-NXX is assigned.

Portable Code: NPA-NXX code from which telephone numbers may be ported.

Pseudo-LRN: A valid LRN is required when a number cannot be routed based on its dialed digits, so an NPAC record is created to show the LRN for that ported (or pooled) number. However, some number records are established in the NPAC/SMS for reasons other than a need for LRN-based routing. Some service providers find in such cases that the use of an intra-SP port to create a conventional NPAC/SMS record, i.e., one containing a valid LRN, is not feasible operationally. Instead a record is created containing a pseudo-LRN - an LRN with a value of 000-000-0000 in the LRN field in lieu of a valid LRN. The digit string in the LRN field of pseudo-LRN records means only that the number should be routed on dialed digits; that is, it is an instruction, not a route choice.

PSAP: Public safety access points.

PSTN (Public Switched Telephone Network): The closed network consisting of interconnections between voice switching nodes identified by national number plans such as the NANP (the plan used for telephone numbers in Canada, the United States and its territories, and the Caribbean). Other network arrangements such as the internet and private networks also interact with PSTN traffic, but rely on the PSTN switching nodes for their access to PSTN traffic.

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Rate Area: Allows a consumer's service location to be defined for purposes such as defining local calling plans and calculating distances to rate long distance calls. (Note: Distance is no longer a component of pricing most toll calls.) It is a geographic area represented by a single point (the "rate center"). The distance between the calling party's rate center and the called party's rate center is used to represent the distance between the two parties. Each NPA-NXX in the NANP (except special purpose codes such as those used for "toll free" numbers) is associated with a rate area. Porting a number has no impact on its rate area association.

Rate Center: see Rate Area.

RBOC (Regional Bell Operating Company): An RBOC is a combination of Bell operating companies. Seven RBOC's were formed as a result of the AT&T divestiture.

RFI: Request for Information

RFP: Request for Proposal

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SCP: Service Control Point. Transaction processor-based system that provides common channel signaling network interface to database services.

SMS: Service Management System. Used to manage records in a database. In the LNP context, the local SMS (LSMS) receives broadcasts from the NPAC/SMS and updates the LSMS operator's downstream databases.

SOA: Service Order Administration. The mechanized device interfaces to the NPAC/SMS to create, modify, or delete NPAC/SMS records. For example, a record must be created when a consumer ports his number.

SP: Service Provider.

SPID: Service Provider Identification Number. (See NPAC SPID.)

SSN: Sub System Number; used as part of a DPC address on the SS7 network. (See DPC.)

SSP: Service Switching Point or service switch point. A switching office that has the SSP features, enabling interactions with SCPs.

SS7: Signaling System 7. An internationally standardized, general-purpose Common Channel Signaling protocol. It defines the signaling backbone for the public switched telephone network.

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.

SV: Subscription Version. The record stored in the NPAC/SMS (and broadcast to LSMSs) that contains routing and other information for a telephone number that is ported or pooled.

SV Type: Identifies the type of service associated with the telephone number or pooled block:  Wireline, Wireless, Class 2 VoIP, VoWIFI (Voice over WiFi), Pre-paid Wireless, Class 1 VoIP.

Service Bureau: Third-party users of NPAC data that relay NPAC data to their clients.

Switch: A device that can be controlled to interconnect two circuits. The local central office switch is used to provide the numbers it serves with the ability to be connected with any other number in the PSTN, i.e., it is the interface to the PSTN for the consumers it serves.

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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.)

TCP/IP: Transmission Control Protocol and Internet Protocol. Internet protocol suite developed by the U.S. Department of Defense in the 1970's. TCP governs the exchange of the sequential data. IP routes outgoing and recognized incoming messages.

Thousands Block: (See Block, see also Pooled Block.)

TN: Telephone Number.

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VoIP: Voice over Internet Protocol

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WAN: Wide Area Network

WPR (Wireless Port Request): The service request to port a number, sent from one SP to another. (WPR if from wireless carrier; LSR if from a wireline carrier).

WPRR (Wireless Port Request Response): Firm Order Confirmation from a wireless service provider. Acknowledgement from one SP to another of receipt of a valid Service Request (LSR if sent from a wireline carrier; WPR if sent from a wireless carrier).

WSMSC: Wireless Short Message Service Center. (See also DPC.)

WWW: World Wide Web

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