Letter of Authorization (LOA) for a Number Port

What an LOA is and why the losing carrier needs it

A letter of authorization (LOA) is the signed form that lets your new phone provider ask your current provider to release your number. AWS describes it as "an industry standard document type used by carriers to authorize the transfer of a phone number from one carrier to another". AWS also notes that it is often specific to the country, the carrier, or the porting relationship between the two carriers ^[1]. That is why every provider hands you its own version instead of accepting a generic template.

The LOA is an authorization, not a contract with your old provider. Signing it does not cancel the old account and does not settle what you owe on it. The FCC's consumer porting guide reminds customers that a contract may contain early termination fees or outstanding balances "that you are obligated to pay". The LOA does one job: it shows that the person who controls the number asked for it to move.

Almost every rejection traces back to the same cause. The current provider compares what you wrote on the LOA with what it has on file, and anything that does not match is a reason to send the request back. This guide covers the US and Canada as of October 2026. It is educational information, not legal advice.

Who is allowed to sign

The signer must be the authorized person on the account at the current provider. Telnyx's instructions ask for "the signature of the authorized person on the account" and warn that the request "may be rejected" if the signature is not clear and legible ^[2].

For a business, that means:

• Business-name accounts: the account owner or an administrator the carrier has on record. A manager who just uses the phone usually is not that person.
• A personal cell used for the business: the person whose name is on that mobile account.
• Numbers bought with a business: if the account is still in the seller's name, the seller signs, or the account is transferred first.

Wireless carriers in the US have a further reason to check who is asking. 47 CFR 52.37(b) tells a wireless provider to "use secure methods to authenticate a customer that are reasonably designed to confirm the customer's identity before effectuating a port-out request". Compliance is not required until the FCC announces a compliance date (52.37(h)), and none had been announced as of October 28, 2026; carriers may already do this voluntarily. Either way, this is why mobile carriers ask for an account PIN or a transfer PIN, and why a signature from the wrong person goes nowhere.

The LOA field by field

Provider forms differ in layout but ask for the same core data. This walk-through follows the Telnyx field list:

Three fields cause most of the trouble:

• Name. "Smith Plumbing Ltd." and "Smith Plumbing" are different strings to a carrier's system. Copy the name from the CSR, not from your letterhead.
• BTN. On a multi-line account, the BTN is often a number you never publish. It is one number, the one the account is billed under, so take it from the bill.
• Numbers to port. List every number, including fax and overflow lines. A number left off the LOA does not move. If some numbers should stay with the old carrier, ask both providers how that partial port will be handled.

A filled-in example, with placeholders only:

LETTER OF AUTHORIZATION – NUMBER PORT

Account / company name:  [exact name on current carrier account]
Service address:         [street number and name], [city], [province/state], [postal/ZIP code]
Current carrier:         [losing carrier name]
Billing telephone no.:   [NPA-NXX-XXXX]
Numbers to port:         [NPA-NXX-XXXX], [NPA-NXX-XXXX]

I authorize [new provider] to act as my agent to port the numbers above
from my current carrier.

Authorized signature:    ______________________
Printed name:            [FULL NAME IN BLOCK LETTERS]
Date:                    [date signed]

Use your new provider's form, not this sketch. As AWS notes, the right LOA depends on the carrier and the porting relationship.

Service address vs billing address

This is the most common mismatch. Telnyx says the address fields "should be the service address on file for the number(s), not the billing address", unless the two are the same ^[2].

Where the two drift apart:

• The bills go to an accountant or a head office, but the line is installed at the shop.
• The business moved and updated its mailing address but not the service record.
• A mobile account carries the owner's home address, not the business address.

Canada adds its own requirement. Twilio's Canadian guidelines say the LOA "must show your actual Canadian service address". The document is sent to your current provider, and "the address must match their records." Rural route, suite and unit details count. Copy them exactly as the carrier has them.

Get the CSR first

The Customer Service Record (CSR) is the current carrier's own record of your account: name, service address, numbers and features. Telnyx recommends requesting it because "a CSR holds all of your account information and will help you with filling out the LOA accurately" ^[2].

Twilio makes the same point from the other side. Its US guidelines require a "name and address that matches the Customer Service Record (CSR)". They also state that "the most common reason for a rejected port is incorrect name and/or address information" ^[3].

How to use the CSR:

1. Call or chat with the current carrier and ask for the CSR (or the name, service address and BTN on file) for each number you are moving.
2. Copy those values into the LOA character for character.
3. If the CSR is wrong (an old address, a former owner's name), ask the carrier to correct it first. Alternatively, put the CSR values on the LOA and fix the record after the port.

What else travels with the LOA

The LOA rarely goes alone. Here is how one provider's published requirements compare across the border:

On PINs, Twilio notes that most mobile operators require account numbers and PINs to port, and some providers also require an account PIN to port out. Ask the current provider before you submit. Our glossary defines the porting terms used here.

What the carrier may and may not ask for (US)

In the US, a federal rule caps the data a carrier can demand for a simple port. The FCC's consumer guide describes simple ports as ones that "generally do not involve more than one line or more complex adjustments" to switching equipment ^[5]. Under 47 CFR 52.36, a carrier "may require only" 14 standard data fields to complete a simple port order. They include the ported telephone number, account number, ZIP code, desired due date, the new network service provider, and "Agency authority status". The passcode field is optional "unless the passcode has been requested and assigned by the end user."

In plain terms:

• For a simple US port, the losing carrier cannot add extra hoops beyond those fields.
• If you set up a passcode or PIN on the account, expect to supply it.
• Multi-line business accounts and partial ports often are not simple ports, so providers may legitimately ask for more.

We found no Canadian equivalent of this field list in the CRTC material reviewed. In Canada, the provider requirements above are the practical guide.

Toll-free numbers use a Letter of Agency with different rules

Toll-free numbers do not move between local carriers. They move between Responsible Organizations (Resp Orgs) in the toll-free registry run by Somos. The document is usually called a Letter of Agency. For a change escalated to the Somos Help Desk, Somos requires each LOA to include four elements ^[6]:

1. Signature of the end user or subscriber: wet signature, electronic signature or PIN. "Stamped signatures will not be accepted."
2. Date within the last 30 days of the change date on the request.
3. The toll-free numbers to be changed. For long lists, "see attached" with the first and last numbers.
4. New Resp Org company information, such as letterhead or text naming the Resp Org being appointed.

Somos also requires:

• No movable text boxes. All information must be locked on the document.
• One page, unless you submit a separate LOA for each number.

Your new provider normally prepares this letter. Your job is to sign it promptly and make sure the subscriber name is right.

Common LOA mistakes that trigger rejection

AWS lists four common reasons a losing carrier rejects an LOA ^[1]:

Unpaid balances: the US rule. The FCC consumer guide states that once you request service from a new company, "your old company cannot refuse to port your number, even if you owe money for an outstanding balance or termination fee." You still owe the money, and the carrier may still ask you to pay it. AWS lists "unsatisfactory business relationship" as a common real-world rejection; if a US carrier rejects a port only over a balance, cite the FCC guidance and ask the new provider to escalate. We found no CRTC rule on this point for Canada, so ask the provider directly.

Other avoidable mistakes:

• A stale LOA. Twilio Canada wants it dated within 30 days, and Somos wants toll-free LOAs within 30 days of the change date. Sign close to submission.
• The wrong signer. A staff member signs for an account in the owner's name.
• Cancelling the old service first. The FCC advises not to terminate the old service before starting with the new company.
• Missing the approval text on a Canadian port (Twilio's 90-minute window).

FAQ

Does an LOA expire?

No FCC or CRTC rule we reviewed sets an expiry. In practice, providers do: Twilio requires Canadian LOAs dated within the last 30 days, and Somos requires toll-free LOAs dated within 30 days of the change date. Sign close to submission, and re-sign if the request stalls.

Do I need to have the LOA notarized?

None of the sources reviewed for this article (AWS, Telnyx, Twilio, Somos, FCC) ask for notarization. If a provider does, that is its own requirement, not a regulatory one.

Can I sign the LOA electronically?

It depends on the provider. For toll-free changes, Somos accepts a wet signature, an electronic signature or a PIN, but not a stamped signature. For local numbers, use the method your new provider offers. Telnyx's guidance stresses only that the signature be clear and legible.

Do I need a separate LOA for each carrier?

Usually. An LOA names one current carrier and one billing telephone number ^[2], so numbers spread across two carriers or two accounts normally need two LOAs. The same logic applies to toll-free numbers held by different Resp Orgs.

For timing once the paperwork is clean, see how long number porting takes. Auto Attendant has you sign the LOA online, charges nothing until the number has moved, and has its team move Canadian and toll-free numbers by hand; the earliest port date you can request is eight days out (how porting works).

Sources

1. Documentation requirements for porting numbers — Amazon Web Services; LOA definition, carrier-specific LOAs, four common rejection reasons. Accessed 2026-10-28.
2. How to fill out an LOA — Telnyx; LOA fields, service vs billing address, BTN, signature, CSR advice. Accessed 2026-10-28.
3. Twilio Voice Guidelines: United States porting — Twilio; US required documents, CSR match, bill within 30 days, PINs, most common rejection reason. Provider practice. Accessed 2026-10-28.
4. Twilio Voice Guidelines: Canada porting — Twilio; LOA within 30 days, Canadian service address, bill, account number, PIN, 90-minute SMS approval. Provider practice. Accessed 2026-10-28.
5. How do I submit a ROC HDI request (Letter of Agency requirements) — Somos; toll-free Letter of Agency elements, 30-day date rule, signature types, formatting rules. Accessed 2026-10-28.
6. 47 CFR 52.36, Standard data fields for simple port order processing — eCFR (US); the only data a carrier may require for a simple port; passcode optional unless assigned. Accessed 2026-10-28.
7. 47 CFR 52.37, Number Portability Requirements for Wireless Providers — eCFR (US); wireless port-out authentication and compliance-date paragraph. Accessed 2026-10-28.
8. Porting: Keeping Your Phone Number When You Change Providers — FCC (US); fees and balances, no refusal over unpaid balance, simple-port definition, do not cancel first. Read via web.archive.org copy dated 22 October 2026. Accessed 2026-10-28.