What is LNP?

Local Number Portability (LNP), also known as number portability and number porting, enables end users to keep their telephone number when switching from one telecommunications service provider to another. Prior to the introduction of LNP, changing service providers meant having to get a new telephone number. Number porting changed that, making it possible for consumers to retain the same telephone number.

History of Local Number Portability (LNP)

Local number portability is a relatively new process that was mandated in the U.S. by the Telecommunications Act of 1996. The act provided the regulatory framework for LNP implementation, intended to provide competition in the local telephone services market after deregulation of the telephone industry in 1984. However, a number of events between 1984 and 1996 led to the development and implementation of LNP in the U.S.

Prior to 1984, one telephone company, AT&T, owned and administered the distribution of all telephone numbers to the other telephone companies. The telephone number represented the physical switch address of the originating and/or terminating local office (Area code, Exchange and Line Number).

The Evolution of the Telephone Number

Introduced Telephone Number How Connected
1890s Beacon Hill XXXX Operator Connected
1910s BEH-XXXX 3 Letters, 4 Numbers
1930s EH5-XXXX 2 Letters, 5 Numbers
1950s 684-XXXX All Number Dialing
1960s (703) 684-XXXX 10 Digit Dialing
1995 (571) 684-XXXX North American Numbering Plan

1984 – 1996

In 1984, the AT&T divestiture led to the formation of seven independent Regional Bell Operating Companies RBOCs): AmeriTech, Bell Atlantic, BellSouth, NYNEX, Pacific Telesis, Southwestern Bell and US West. The seven RBOCs controlled the distribution of all telephone numbers in their territories. Competition for long distance service opened, creating the need to correlate a telephone number to the long distance provider.

1996 – Telecommunications Act of 1996

The Telecommunications Act of 1996 was enacted to spur competition in the communications industry and was the first major overhaul of the law governing telecommunications in the U.S. since 1934. Key provisions:

  • Local number portability that enables end users to switch service providers and retain their telephone numbers.
  • Preemption that allowed the FCC  to preempt state or local legal requirements that acted as barriers to entry in the provision of interstate or intrastate telecommunications service.
  • Interconnectedness that obligated incumbent carriers and new entrants to connect their networks and setting terms, conditions and rates that would not undermine competition.
  • Intercarrier compensation needed to charge and bill for calls that take place using different networks. In the U.S., the calling party’s carrier traditionally pays the called party’s carrier for completing the call.
  • RBOCs may enter long distance to encourage competition in the long distance and local markets.
  • Wholesale access to incumbents' network gave new entrants access at cost-based, wholesale rates and time to build out their own networks.
  • Universal service support made explicit to ensure rules and regulations are in place to support the availability of telephone service throughout the U.S.

After 1996

Simply put, managing telephone numbers instantly got complex in 1996. Instead of the seven regional RBOCs controlling and managing numbers in their regions, telephone numbers could now be moved between service providers. The number of service providers increased and decreased each year as new communication technologies and services were introduced or expanded. New technologies like VoIP and the delivery of media over IP now sit at the forefront and have in ways eclipsed older circuit-switched telephony.

Carriers needed to work together to establish processing flows, system requirements, and specifications to design, build, and administer the exchange of carrier data – the system that is the Number Portability Administration Center, the NPAC.

Benefits of Local Number Portability

For Consumers For Communications Service Providers
Enables a consumer to keep the same telephone number when changing to another service provider. Encourages technology innovation.
Increases willingness of the consumer to change to another service provider, increasing competition. Stimulates demand for telecommunications services.
Increased competition gives the consumer more choices and reduces prices. Boosts economic growth in the U.S.


In 1999, the industry faced a crisis with the exhaust of central office codes (NPA-NXX). In 1947, only 78 area codes were assigned to carriers in the U.S. Only 36 new area codes were added through 1989. But the proliferation of new service providers (CLECs, wireless carriers, etc.) rapidly increased the need for central office codes. By the late 1990s, 109 new area codes were activated in the U.S. to meet the demand for central office codes. The industry was faced with exhausting the pool of NPAs and moving to a system that required more than 10 digits for each telephone number in order to increase the supply of these codes.

The FCC issued a report on numbering resource utilization in the U.S. that recommended "thousands-block number pooling". Historically, all 10,000 telephone numbers associated to a central office code were assigned to a single service provider. Many providers were too small to use all 10,000 numbers, while larger providers needed additional numbers. Pooling was introduced to allow the 10,000 numbers associated with a central office code to be broken into ten sequential blocks of 1,000 numbers each, making it possible to assign only one central office code to accommodate multiple carriers serving the same rate area. Service providers are now required to report on their number utilization and to donate unused or underutilized blocks of telephone numbers to the National Pooling Administrator, so that the spare blocks can be assigned to other carriers in need of numbers.

LNP Highlights

  • 1996: Telecommunications Act signed into law, opening local markets to competition
  • 1996: FCC First Report and Order, Docket 95-116 provided the regulatory framework to make LNP a reality
  • 1997: LRN method adopted by FCC as the de facto industry standard
  • 1997: Request for Proposal released for the NPAC Service Management System to support the implementation of Number Portability in one Chicago, Illinois, LATA
  • 1997: Seven U.S. databases established coinciding with the seven original Bell Operating Company regions; first number ported in Maryland
  • 1997: Neustar (then CIS, an operating division of Lockheed Martin) becomes the sole provider of NPAC services for all seven LLCs and the Canadian LNP Consortium
  • 1998: Canada NPAC established
  • 1998: LNP implemented in the top 100 MSAs  by the end of 1998; outside of the top 100 MSAs, a service provider must implement LNP after receiving a bona fide request to do so
  • 2003: Wireless number portability implemented