Number porting (also called Local Number Portability, LNP) is the regulated process of moving a phone number between carriers. The FCC requires US carriers to release simple ports in one business day; in practice, most ports complete in 1–3 business days end-to-end.
There are two directions:
- Port-in — bringing an existing number to a new carrier. The destination carrier (the one you're joining) coordinates with the source carrier to release the number. You provide the source account number, account PIN, billing name, and service address. - Port-out — leaving a carrier with your number. The destination carrier handles the request; the original carrier must release.
Some ports take longer: VoIP-to-cellular ports often take 2–3 days, and ports involving certain prepaid carriers, regional MVNOs, or carrier disputes can take 5–21 days. Toll-free ports follow a different process and typically take 4–7 business days.