Number Portability LNP

US (LNP); Canada has its own regime · also called LNP, local number portability, porting

The ability to keep your telephone number when switching carriers — which breaks the link between a number and its original assignee.

Number portability (in the US, Local Number Portability or LNP) lets a subscriber keep their telephone number when changing service providers, moving within a rate center, or switching between wireline and wireless. It is implemented through the Number Portability Administration Center (NPAC) — operated in the US by iconectiv (which took over from Neustar) — which maps a ported number to its serving network via a Location Routing Number.

Portability is the single most important reason that a number's original assignee is not a reliable indicator of its current service provider.

Carrier names are illustrative. The lesson is real: the assignment record (who a prefix was handed to) is not the current carrier (who serves a number now). After a port they differ — which is why an area code, or an old assignment table, cannot tell you who a number belongs to today.

Common misconception.

Portability does not change a number's area code or its original-assignee record. It changes which network serves the number — invisibly to anyone reading assignment data.