The Number Portability Administration Center (NPAC) is operated by Neustar, and serves as the central mediation center for all LNP activity. The NPAC Service Management System (SMS) is used by the NPAC personnel to facilitate the porting of numbers. The NPAC is considered the telecom industry's common, authoritative database used for routing, rating and billing calls for telephone numbers that are no longer assigned to the original NPA-NXX code holder. There is a separate NPAC SMS for each of the seven traditional RBOC regions in the US and an eighth system for Canada. The systems are all physically located in Sterling, VA with a backup site in Charlotte, NC.

Every Communications Service Provider that participates in LNP exchanges porting information with the NPAC SMS. Typically, subscription information is sent to the NPAC via the Low Tech Interface (LTI) or through the Communication Service Provider’s Service Order Administration (SOA) system. Porting notifications are received from the NPAC via the same systems. When a ported number is activated, network downloads are received from the NPAC SMS through the Communication Service Provider’s Local Service Management System (LSMS). The LTI is a Web-based screen that is accessed through the NPAC. A number of companies offer SOA and LSMS products. SOA products may be stand-alone or integrated with other parts of the OSS. LSMS products may be stand-alone or integrated with other network elements such as the STP.. Communications Service Providers can also contract with a service bureau for the SOA and LSMS functionality.

Once a communications service provider becomes an "NPAC User", the communications service provider can directly or indirectly interact with the NPAC/SMS in the following ways:
 

• Service Order Activation (SOA) - The SOA is used to communicate information to the NPAC SMS and back to the Communications Service Provider.

• Local Service Management System (LSMS) - The LSMS is 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.

• Low Technology Interface (LTI) - The LTI is the graphical user interface (GUI) that can be used instead of the SOA to communicate information to the NPAC SMS and back to the Communications Service Provider.

• NPAC Help Desk - The Communications Service Provider can contact the help desk to communicate information to the NPAC SMS or receive information.

• Or the communications service provider can indirectly interact with the NPAC through an entity known as a Service Bureau.

 
The communications service providers can influence the design of the NPAC SMS through participation in the LNPA Working Group. (The original NPAC/SMS was designed by Neustar based on the requirements established by the communications service providers participating on LNPA WG legacy committees.)  The LNPA WG is a subcommittee of the North American Numbering Council (NANC); the NANC is an advisory body to the FCC on numbering matters.

 In the U.S., those communications service providers that elect to join the NAPM LLC (an administrative combination of the seven regional U.S. LLCs) manage the U.S. NPAC vendor.  In Canada, all communications service providers providing service in Canada are members of the Canadian LNP Consortium.

There are two types of number portability; 

• Service Provider Portability:  Enables users to change providers and retain their telephone number
• **Location (Geographic) Portability:  Allows users to change from one geographic area to another while retaining their telephone number. 

**Currently, only Service Provider Portability has been implemented and is available. 

Service Provider Portability is made technically feasible by the use of the Location Routing Number (LRN) method.  LNP moves the telephone number from the current communications service provider who is providing service to the new communications service provider by changing the physical switch where the number currently resides to the new service provider’s switch.

The LRN is a 10 digit number assigned to each switch from an NPA-NXX code, or Telephone Number, that is unique to that switch. It defines the state and rate center where it was assigned.

A switch is a device that can be controlled to interconnect two circuits. 

There are three reasons a telephone number might need to be ported.

1.  Inter-carrier or competitive porting; moves the number from the communications service provider currently providing service to the new communications service provider who will be  providing service.

2.  Intra Carrier porting; moves the number in the NPAC from one switch to another switch within the same communications service provider's network.

3.  Number Pooling; moves numbers to a new communications service provider in blocks of 1,000 to create an inventory of unassigned phone numbers, e.g., 571-434-5000 through 5999.