Quite simply, LNP, or number porting, is a system that enables end users to keep their telephone numbers when switching from one communications service provider to another. When deregulation came to the telephone industry, many new service providers emerged, giving consumers a choice of services and prices. Yet, switching to a new provider meant getting a new telephone number. Number portability changed that, making it easy for consumers to freely select the communications service provider of their choice and retain the same telephone number. Read more about the history of LNP, why it exists, how it works and how it is managed.
For an exhaustive overview of Number Porting, please check out this overview: https://www.npac.com/number-portability/what-is-lnp
We have borrowed heavily from this resource for this KB guide
How Porting Works
Local Number Portability is made technically feasible by the Location Routing Number (LRN), a unique 10-digit telephone number assigned to each switch. The LRN approach made it possible to introduce LNP without radically changing the Public Switched Telephone Network. It allowed the existing routing paradigm to remain in place, permitting a gradual conversion of the network to handle LNP traffic.
Before LNP was established, the NPA-NXX of a telephone number identified the state and rate center where the number was originally assigned, the service provider and the carrier type (wireline or wireless). Today, because telephone numbers have been ported between wireline and wireless service providers, the NPA-NXX of a telephone number only identifies the state and rate center where the number was originally assigned. The LRN’s NPA-NXX now serves as the network address that helps communications service providers cost-effectively route calls and traffic to their proper destinations.
Calls are routed based on the first six digits (NPA-NXX) of the telephone number. The NPA-NXX is the address of the switch serving the telephone number. When a number is ported, the 10 digit LRN is associated with the ported number. Calls to the ported number are instead routed based on the NPA-NXX of the 10 digit LRN.
Before LNP was established, the NPA-NXX of a telephone number identified the switch serving the number, the state and rate center where the number was originally assigned as well as the service provider. Because LNP allows a number to be moved from one switch to another, the NPA-NXX of a telephone number is no longer a reliable indicator of the serving switch and service provider's identity. Today, since numbers have been ported between wireline and wireless service providers, the NPA-NXX of a telephone number no longer can be relied on to determine whether the number is served by a wireline or wireless service provider.
Steps in the LNP Porting Process
To understand the steps in the porting process, it may be helpful to explain the steps of the process. Below is a high-level summary of the processing steps and porting process for a typical competitive port. In this case, a consumer is switching to a new communications service provider and wants to keep his existing telephone number.
- The new service provider notifies the old service provider of the requested port.
- The old service provider is asked to validate the subscriber's information.
- The old service provider confirms the subscriber's information and notifies the new service provider.
- The new service provider notifies the NPAC of the requested port.
- The NPAC creates a pending port and sends a notification to the old service provider.
- Optionally, the old service provider notifies the NPAC that it concurs with the port.
- The new service provider notifies the NPAC to activate the port.
- The pending port is activated in the NPAC and broadcast to the telecommunications industry network within milli-seconds.
NPAC is the organization that centralizes telecommunications routing. They work like a DNS provider for the entire telecommunications industry.