Number Porting: Move Numbers to a New Carrier

Your phone numbers belong to you, not to your carrier. FCC regulations guarantee your right to take your numbers to any carrier you choose through a process called number porting. This guarantee exists because without it, carriers could hold your phone numbers hostage — keep paying us or lose the numbers your customers know. The FCC eliminated that leverage through Local Number Portability (LNP) rules that have been in effect since the late 1990s.

Despite the regulatory guarantee, porting is the process operators dread most when switching carriers. Not because it is technically complex — it is straightforward — but because it involves coordination between your old carrier (who may not be eager to see you leave), your new carrier (who needs to execute the port correctly), and a national database system that must update routing for every ported number. When any step in this chain goes wrong, the port is delayed. Understanding the process helps you avoid the common mistakes that cause delays.

SIPNEX is an FCC-licensed carrier that handles number porting daily. We manage the port submission, FOC coordination, and cutover on your behalf. This guide explains how the process works so you know what to expect.

What number porting is

Number porting (formally Local Number Portability or LNP) is the process of moving a phone number from one carrier (the “losing carrier” or “old carrier”) to another carrier (the “gaining carrier” or “new carrier”) while keeping the same phone number. After the port completes, calls to that number are routed to the new carrier’s network instead of the old carrier’s network. The number itself does not change — only the carrier behind it changes.

Porting is managed through the NPAC (Number Portability Administration Center), a national database that maintains the routing information for all ported numbers in North America. When a number is ported, the NPAC record is updated to point to the gaining carrier. Every carrier in the telephone network queries the NPAC (directly or indirectly) to determine where to route calls for ported numbers.

The porting process step by step

Step 1: Gather your current account information. Before initiating a port, you need: the authorized name on your current carrier account (must match exactly), your account number with the current carrier, your account PIN or passcode (if your carrier uses one), the billing address on the account, and the phone numbers you want to port. This information must match your current carrier’s records exactly — a character mismatch on the authorized name or a wrong account number will cause a rejection.

Step 2: Submit a Letter of Authorization (LOA). The LOA is a document that authorizes the gaining carrier to port your numbers. It includes your name and business name, the phone numbers to port, your current carrier’s account information, and your signature (electronic or physical). SIPNEX provides a standardized LOA form — you fill in the details and sign it. We submit it as part of the port request.

Step 3: The gaining carrier submits the port request. SIPNEX submits your port request through the NPAC system (or through our interconnection agreements with the losing carrier, depending on the carrier type). The request identifies the numbers being ported, the gaining carrier (SIPNEX), and the losing carrier.

Step 4: The losing carrier reviews and confirms. The losing carrier receives the port request and has a defined window to review it. They verify that the information matches their records. If everything matches, they confirm the port and a FOC (Firm Order Commitment) date is set — this is the date the port will execute. If information does not match, they reject the port with a reason code, and you need to correct the LOA and resubmit.

Step 5: FOC date — the port executes. On the FOC date, the NPAC database is updated to route calls for your numbers to SIPNEX’s network. Your numbers are now live on SIPNEX. Calls to those numbers arrive at your SIP trunk endpoint. Outbound calls presenting those numbers are signed with SIPNEX STIR/SHAKEN attestation.

Step 6: Verification and old carrier cancellation. After the port completes, verify that inbound calls route correctly and that outbound CID works. Once confirmed, the old carrier’s service for those numbers terminates automatically (the numbers are no longer on their network). Your old carrier may continue billing for the month depending on their billing cycle — review your final invoice.

Timelines

Simple ports (1-10 local numbers from one carrier): 7 to 14 business days from LOA submission to FOC date. This is the standard timeline for most business ports.

Complex ports (large blocks, multiple carriers, or wireless numbers): 14 to 21 business days or more. Ports involving hundreds of numbers, multiple losing carriers, or numbers that require coordination across different systems take longer.

Toll-free number ports: Toll-free numbers use a different process — RespOrg transfer through the SMS/800 system rather than LNP through the NPAC. Timeline: 5 to 15 business days depending on the current RespOrg’s cooperation.

Wireless to VoIP ports: Porting a cell phone number to a VoIP carrier follows the standard LNP process but may take slightly longer (10 to 14 business days) because wireless carriers sometimes process ports more slowly than landline or VoIP carriers.

Common causes of port delays

Mismatched account information. The #1 cause of port rejections. The authorized name on the LOA must match the name on the losing carrier’s account exactly. “John Smith” does not match “John R. Smith.” “ABC Company LLC” does not match “ABC Company.” Before submitting your LOA, call your current carrier and confirm the exact name, account number, and PIN on file. Write it down character by character.

Account has pending orders. If there is an active order on your current carrier account (a feature change, an upgrade, a pending disconnect), some carriers will reject the port until the pending order clears. Resolve any open orders before initiating the port.

Partial port confusion. If you are porting some but not all numbers from your current account, the losing carrier must process a partial port. Some carriers handle partial ports smoothly. Others struggle with them. If possible, port all numbers from an account simultaneously to avoid partial-port complications.

BTN (Billing Telephone Number) conflict. If the number you are porting is the BTN (primary billing number) on the account and other numbers remain, the losing carrier must assign a new BTN to the account before releasing the ported number. This adds a step and can delay the port. Solution: if you are porting the BTN, tell your current carrier in advance so they can reassign it.

Losing carrier delays. Some carriers process port requests slowly — either due to operational inefficiency or as a retention tactic (making it painful to leave). While the FCC has rules about timely port processing, enforcement is imperfect. If your port is delayed beyond reasonable timelines, SIPNEX can escalate through industry channels and, if necessary, file an FCC complaint on your behalf.

During the port: no service interruption

A properly executed port has zero service interruption. Here is why:

Your numbers remain active on the losing carrier until the FOC date. On the FOC date, the NPAC record is updated and calls begin routing to SIPNEX. The cutover happens at the network routing level — there is no physical disconnection and reconnection. One moment your number routes to the old carrier; the next moment it routes to SIPNEX. If you have already configured your SIP trunk and tested with new SIPNEX DIDs, the ported numbers light up on your system the moment the routing switches.

The parallel operation strategy: While the port processes, you can immediately start using new SIPNEX DIDs for outbound calling. Your campaigns continue on new numbers while your established numbers port in the background. When the port completes, add the ported numbers to your CID rotation and inbound routing. This ensures zero downtime — you are operational on SIPNEX from day one, and your ported numbers join the existing configuration when they arrive.

After the port

CNAM registration. Ported numbers may retain the old carrier’s CNAM record. SIPNEX re-registers CNAM as part of the post-port process. Allow 24 to 72 hours for propagation.

STIR/SHAKEN verification. Ported numbers are added to your SIPNEX STIR/SHAKEN authorized CID list upon port completion. Outbound calls using ported numbers receive A-level attestation immediately.

Caller ID reputation. Your ported numbers carry their existing reputation history. If the numbers had good reputation on the old carrier, they retain it. If they were flagged, the flag follows the number — CNAM and attestation improvements will help, but reputation remediation may be needed.

Old carrier final billing. Review your final invoice from the losing carrier. Confirm that billing stops for the ported numbers. Some carriers continue billing until the end of the billing cycle. Dispute any charges after the port completion date for ported numbers.

Frequently asked questions

SIPNEX handles number porting as part of our standard SIP trunk provisioning — we manage the LOA submission, FOC coordination, and cutover. No porting fees. No service interruption. Your numbers arrive on a trunk with A-level STIR/SHAKEN attestation and CNAM registration ready to go. Start your port or see our rates.