LNP primarily helps telecom end users access the existing number regardless of their physical location or the service provider being used. For example, through LNP, a local resident can carry/port an existing number even if they have moved to a new provider, a new home or even a new city.

Typically, LNP works through a local routing number (LRN) service that provides call routing service for telecommunication operators. In the U.S., LNP and LRN are managed by number portability administration centers (NPAC), which generate a new LRN each time a customer switches providers and send that LRN to the new provider to help them route calls for that number.