Keep your number

How to port a fax number,
step by step.

What your carrier will ask for, how long the rules allow, and what causes the first attempt to be rejected. Written from the carriers’ own porting rules and our carrier’s published policy.

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Last updated · Written for practice managers and office administrators.

The steps

  1. Portability check. Enter the number. You learn the carrier of record and whether the number is eligible to move.
  2. Collect the account details from the most recent bill (dated within 30 days): account number, account-holder name, service address, and any PIN or security code printed on it.
  3. Sign the Letter of Authorization (LOA) online. The signer must be the authorized person on the carrier account; the LOA must be signed within the last 90 days and list every number being ported.
  4. Upload the bill. It must be from the current (losing) carrier and show the number.
  5. Submission. Telnyx submits a simple port to the losing carrier within two business days of a complete order (four for non-simple).
  6. Firm order confirmation. The losing carrier returns a confirmed port date (FOC) or a rejection with a reason. Telnyx reports rejections within 48 business hours.
  7. Activation on the FOC date, Monday to Friday, 9 a.m. to 5 p.m. Central. Same-day FOCs are not accepted; changes need to be requested by 2 p.m. Central the day before.
  8. Test and cancel. Confirm inbound works, then cancel the old service. Not before.

Timelines, by rule and in practice

Porting timelines
StageRule or policySource
Simple wireline portCarrier must complete within one business day of a complete request; requests received 8 a.m.–1 p.m. local time are eligible for activation at midnight that day.47 CFR § 52.35
Non-simple portWithin four business days.47 CFR § 52.35
Start to finish, simpleSubmitted to losing carrier within 2 business days; estimated completion 7 business days.Telnyx porting policy
Start to finish, non-simpleSubmitted within 4 business days; estimated 15 business days or more.Telnyx porting policy
Verizon landline (consumer page)“2 to 10 business days.”Verizon LNP FAQs
AT&T Business Local Network ServicesMinimum 3 business days from submission to requested FOC date.AT&T LNP port-out procedures

What each carrier asks for

The losing carrier validates the request against its own customer record. The fields differ by carrier, and so does what they call the PIN. Where a carrier’s own page could not be read, the row says so and cites a secondary source; confirm with the carrier.

Account number and PIN requirements by carrier
CarrierAccount numberPIN / passcodeNotes
AT&T (traditional lines)Your 10-digit phone number (secondary source).The 3–4 digit customer code printed next to the phone number on the bill (secondary source). AT&T’s own pages describe a transfer PIN only for wireless.AT&T requires an LOA before the request is submitted. Pending order activity on the account results in a reject. If the billing number ports, a new billing number must be named for remaining lines.
Verizon (wireline / Fios)From the bill.The 4-digit account PIN you created (secondary source). The 7-day Number Transfer PIN is a wireless construct.Verizon Business validates at most four fields: phone number, account number, 5-digit ZIP, and pass code if applicable. Keep the account open until the move completes.
Lumen / CenturyLink13 digits: the phone number plus the 3-digit customer code.None — the wholesale rules list the pass code as not applicable.A freeze on the line must be removed first (call CenturyLink). Lines carrying broadband, Centrex, DID or remote call forwarding are not simple ports. A disconnected number cannot be ported.
FrontierThe full 17-digit account number that begins with your phone number (secondary source; Frontier’s page could not be read).Printed on page 1 of the bill (secondary source).Do not cancel before the port completes.
Comcast Business / Xfinity VoiceFrom the invoice.The 4-digit Voice Security PIN. Only the primary manager can view it (My Account → Phone → Manager Settings); Xfinity mails a new one and cannot reset it by phone.Every line on the order must be active and provisioned. Ask for the PIN on day one; it may arrive by post.
Spectrum (Charter)Top-left of the bill.Published rules validate account number, phone number and ZIP; the bill’s “Security Code” is what customers are usually asked for (secondary source).Spectrum publishes its rejection reasons: wrong authorized contact, address not matching the billing statement, an open work order, number not on the statement, inactive number. Disconnecting before the port completes risks losing the number.
CoxFrom the bill.The 4-digit PIN printed on the bill (top-right, above the service address on business bills).Cox’s terms state the customer has no property right in the number; early-termination charges follow the contract.
VoIP services (RingCentral, Vonage, Ooma, 8x8, Google Voice)Ask the provider for the underlying carrier’s account number.The carrier-level PIN, not your login to the reseller’s platform.Telnyx documents the trap: when leaving a reseller, authorization must come from the underlying carrier. Ask: “What is the underlying carrier for my numbers, and what account number and PIN do I need to authorize the port?”

Why ports get rejected, and how to avoid it

  1. Name or address does not match the carrier’s record. The most frequent cause across carriers. Copy the bill exactly: suite formatting, “Inc.” or “PLLC”, the person’s name as printed.
  2. Wrong PIN, or the wrong account-number format. Telnyx names a mismatched PIN as the top cause of delay. Use the table above; do not use an old PIN if the carrier generates a new one each time.
  3. A pending order on the account. AT&T rejects when there is pending order activity; Spectrum lists an open work order. Finish or cancel other changes first.
  4. Partial port without a new billing number. If the fax line is the main number on an account with other lines, the carrier needs to be told which number becomes the new billing number. Tell us up front.
  5. Line inactive, frozen, or carrying another service. A disconnected number cannot be ported; DSL on the same loop, a hunt group, or a carrier freeze all block it. Clear those first.

Costs and contracts

Porting to usfax is free on Solo, Practice and Multi-site. The losing carrier can still bill its final invoice and any early-termination charge in your agreement; Cox and Spectrum both say so in their business terms, and taking a phone line out of a cable bundle may re-price the internet or TV that stays. Check the contract before you commit to a date. The port itself cannot be refused for money owed.

Frequently asked questions

A simple port moves a single line on its own account with no complex switch features and no reseller in the middle. Federal rules require it to complete within one business day of a complete request. Anything else — several numbers on one account, a line that also carries DSL, a Centrex or hunt-group line — is non-simple and has a four-business-day interval, plus more validation on the carrier side.

Give the address as it appears on the bill, and tell us if the service address differs. Traditional carriers validate against the service address on the customer service record; Spectrum states it matches the address on the billing statement. When in doubt, copy the bill exactly, including suite and unit formatting.

Several wireline carriers validate on the account number rather than a PIN. CenturyLink's wholesale rules list the pass code as not applicable and validate on the 13-digit account number (phone number plus a 3-digit code). Spectrum's published rules validate account number, telephone number and ZIP. If the bill prints a security code or PIN, include it anyway.

No. The FCC's consumer guide states that your old company cannot refuse to port your number even if you owe money for an outstanding balance or termination fee. The carrier can still bill you for what you owe under your contract.

Telnyx activates the number on the confirmed FOC date, Monday to Friday during business hours. Inbound faxes to the number start arriving in your usfax inbox; the old line stops carrying the number. Send a test fax to yourself, then cancel the old service.

Keep your fax number

Enter the number and we check whether it can move, which carrier holds it, and what your carrier will ask for. Free, takes about a minute, no card needed. Porting is free on every subscription plan.

Run the free portability check

Sources

Facts about carriers, regulators and competitors on this page come from the documents below, read on the dates shown. Carrier rules change; when a detail matters for your line, check with your carrier.

  1. 47 CFR § 52.35 — Porting intervals Cornell LII (eCFR text), accessed September 21, 2026.
  2. FCC 10-85 — Local Number Portability Porting Interval and Validation Requirements (Report and Order) Federal Communications Commission, accessed September 8, 2026.
  3. Keeping Your Telephone Number When Changing Service Providers (consumer guide) Federal Communications Commission, accessed September 8, 2026.
  4. Porting requirements (LOA, invoice, PIN) Telnyx, accessed September 8, 2026.
  5. Porting policy and procedure (timelines) Telnyx, accessed September 8, 2026.
  6. Number porting rules and guidelines (rejections, FOC validity) Telnyx, accessed September 8, 2026.
  7. How to find your porting PIN or passcode Telnyx, accessed September 8, 2026.
  8. Porting numbers away from resellers (Aircall, RingCentral, Vonage, …) Telnyx, accessed September 8, 2026.
  9. AT&T LNP port-out procedures AT&T, accessed September 8, 2026.
  10. Verizon Business Local Number Portability guide Verizon, accessed September 8, 2026.
  11. Local Number Portability FAQs Verizon, accessed September 8, 2026.
  12. CenturyLink wholesale Local Number Portability product catalog CenturyLink / Lumen, accessed September 8, 2026.
  13. Transfer your home phone number CenturyLink / Lumen, accessed September 8, 2026.
  14. Comcast Business Voice / VoiceEdge Security PIN Comcast Business, accessed September 8, 2026.
  15. View or change your Voice Security PIN Xfinity, accessed September 8, 2026.
  16. Local Number Portability business rules Spectrum (Charter), accessed September 8, 2026.
  17. What are the reasons my port-out request may be rejected? Spectrum Enterprise, accessed September 8, 2026.
  18. When should I disconnect my Spectrum account when porting out? Spectrum Enterprise, accessed September 8, 2026.
  19. Locating your Cox PIN Cox Business, accessed September 8, 2026.
  20. Carrier porting information (account number and PIN by carrier) US Mobile (secondary) (secondary source), accessed September 8, 2026.
  21. Bandwidth porting guide Bandwidth, accessed September 8, 2026.
  22. usfax.com Terms of Service (cancellation, refunds, porting) usfax.com, accessed September 21, 2026.