Number porting is Local Number Portability (LNP): the subscriber keeps a telephone number when changing service providers. In the United States the Federal Communications Commission requires telecommunications carriers and interconnected VoIP providers to support LNP. The public still dials the same E.164 / NANP digits. Behind the scenes, routing follows a Location Routing Number (LRN) stored in the Number Portability Administration Center (NPAC), not the original NPA-NXX’s incumbent switch.
Winning carrier vs losing carrier
- Winning carrier (gaining / new provider)
- The provider the customer is moving to. The customer authorizes that provider to pull the number. The winning carrier submits the port request and, after the FOC, activates service and updates NPAC.
- Losing carrier (old / current provider)
- The provider that currently serves the number. It validates the request and returns a Firm Order Confirmation or a reject. It cannot hold a valid port hostage. After the port, it stops serving the number.
- Customer of record
- The name, billing telephone number, ZIP, and (for wireless) account number / PIN must match the losing carrier’s Customer Service Record. Mismatches are the most common cause of rejects.
LSR, FOC date, and NPAC
- The winning carrier builds a Local Service Request (LSR) with the standardized simple-port fields (FCC / NANC data set: number, customer name, service address, authorizing name, and related identifiers).
- The losing carrier must respond with a Firm Order Confirmation (FOC) or a reject. For simple ports the FCC adopted a four-business-hour LSR-to-FOC interval.
- The FOC date is the date the losing carrier commits to completing the port. Activation is coordinated to that date (simple ports: typically midnight of the eligible business day).
- On completion, NPAC (the Number Portability Administration Center) broadcasts a subscription version: the number now maps to the winning carrier’s LRN. Other networks query NPAC (or their local LNP database) so subsequent calls and messages route to the new provider.
NPAC is the central LNP database for the United States and Canada. Carriers query it (or a download of it) to translate a dialed number into an LRN. Without that translation, a ported DID would still ring the old switch.
Wireless vs wireline timelines
The FCC’s one-business-day interval (47 C.F.R. § 52.35) applies to simple wireline-to-wireline and simple intermodal ports. A simple port is a single-line port without complex features (no unbundled network elements, no complex hunting rearrangements, and the other NANC simple-port criteria). Non-simple wireline and non-simple intermodal ports have historically used a longer interval (commonly cited as four business days).
Wireless-to-wireless ports were already operated on a faster industry process (often hours when the account number and PIN match). Interconnected VoIP providers are inside the LNP rules (FCC 07-188 and later orders). Toll-free numbers do not use NPAC LRN porting; they move by RespOrg change in the SMS/800 database. See Toll-free numbers.
| Port type | Governing process | Typical interval | Notes |
|---|---|---|---|
| Simple wireline-to-wireline | FCC LNP; LSR / FOC; NPAC | One business day | Complete LSR by 1 p.m. local (NPAC region TZ) is eligible for midnight activation that day. After 1 p.m. counts as the next business day. |
| Simple intermodal (wireline ↔ wireless, including many VoIP ports) | FCC LNP; LSR / FOC; NPAC | One business day | Same simple-port clock as wireline-to-wireline when the port meets NANC simple criteria. |
| Non-simple wireline / intermodal | FCC LNP; longer NANC flows | Longer than one day (classically four business days) | Multi-line, complex features, directory listings, or other non-simple flags. |
| Wireless-to-wireless | CTIA / wireless LNP process; NPAC | Often same day or a few hours when validation succeeds | Account number and port-out PIN are the usual validators. FCC simple-port one-day rule was aimed at wireline and intermodal, not at slowing wireless. |
| Toll-free 8XX | RespOrg change in SMS/800 (Somos), not NPAC LRN | Hours to a few business days depending on RespOrg and validation | Different database and different authority. See Toll-free numbers. |
What happens at the cutover
- Voice: calls follow the new LRN. Inbound Inbound traffic to the old carrier stops once NPAC is updated.
- Messaging: SMS / MMS routing also follows LNP, but 10DLC and toll-free texting registrations do not move automatically with the voice port. The new provider must have the number on an approved campaign or verification.
- E911: the new provider must load the callback number and service address into its emergency routing database. A port without an E911 record is a safety failure, not just a provisioning miss.
- CNAM and Caller ID listings may need a fresh submission at the gaining provider. They are not guaranteed to follow the port.