Glossary of Terms

A unique 10-digit number (in the format of a telephone number) that identifies a specific telephone switch or point of interconnection in the public switched telephone network (PSTN). When a number is ported, the LRN associated with it is updated so calls can be routed to the correct network/switch, regardless of the original area code and prefix.

The entity responsible for managing the databases that support LNP (Local Number Portability) in the United States. It contains the authoritative information on all ported and pooled telephone numbers.

A four-digit alpha-numeric value that identifies a specific service provider to the NPAC. It is often derived from the service provider's Operating Company Number (OCN).

An optional field that identifies a second service provider associated with a telephone number, typically a wholesale provider who has a business relationship with the network provider.

Refers to the specific SPID that identifies the current owner of a telephone number's record within the NPAC system.

A code used to identify a specific operating telephone company. In many cases, a company's OCN is used as their SPID in the NPAC.

A geographic region that defines the boundaries for local telephone service. LATAs were established by the 1984 AT&T divestiture to separate local and long-distance calling for regulatory purposes. Calls within a LATA are considered local; calls crossing LATA boundaries are long-distance.

A telephone company that provides local telephone service. LECs are classified as ILECs (Incumbent LECs, the original monopoly carriers) or CLECs (Competitive LECs, newer entrants). The LEC field in routing data identifies which carrier currently serves the number.

A telecommunications provider that competes with the incumbent carrier (ILEC) in a given area. Examples include Bandwidth.com, Lumen (Level 3), and most VoIP carriers.

The original, established telephone company in a given region, typically a former Bell Operating Company or independent telephone company. Examples include AT&T, Verizon, and CenturyLink.

A data field that identifies the type of service associated with a telephone number (TN) or a pooled block of numbers. Examples include Wireline, Wireless, Class 1 VoIP, Class 2 VoIP, and prepaid wireless.

The ability for a telephone subscriber to keep their phone number when switching service providers. LNP is mandated by the FCC and managed through the NPAC system.

The 15-character caller identification name stored in the Line Information Database (LIDB). When a call is placed, the terminating carrier queries the LIDB to retrieve the caller's name and display it on the recipient's phone. CNAM is separate from the routing/portability data.

A database maintained by carriers that stores subscriber information, primarily the Caller Name (CNAM) associated with each telephone number. When carriers need to display caller ID, they query the LIDB of the number's originating carrier.

A specific geographic area used by carriers for billing and call routing. Rate centers determine whether a call is local or toll, and are defined by the carrier's tariff. Each telephone number is assigned to a rate center.