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Home > Guides > Fax number porting
In most cases, yes: fax numbers are portable between providers in the US and Canada, just like voice numbers. The transfer is handled provider-to-provider and takes days, not minutes. One honest note first: LetterAgent only sends faxes and does not host fax numbers, so you cannot port a number to LetterAgent.
If you are moving from a physical fax machine to a hosted fax-number provider (one that receives faxes for you and delivers them by email or app), here is how the process actually works.
You start with the new provider, not the old one. You sign up, request a port, and give them authorization to take the number. They contact your current carrier, the carriers coordinate behind the scenes, and on the cutover day the number starts ringing at the new provider. Your job is mostly paperwork and patience. The old carrier is not allowed to hold your number hostage, but they are allowed to be slow.
| Step | Who does it | What you provide |
|---|---|---|
| Request the port | You, with the new provider | The fax number and your current account details |
| Authorization | You | A signed Letter of Authorization and a recent bill from the old carrier |
| Carrier coordination | The two providers | Nothing; this is the waiting part |
| Cutover | The new provider | A test fax to confirm the number now reaches the new service |
| Cancel the old line | You | Only after the test fax succeeds |
The Letter of Authorization is the big one: it proves you own the number and permits the move. The recent bill matters because the name and address on it must match the carrier's records exactly. This is where most ports stall. If the account is under "ABC Dental Corp" but you write "ABC Dental", or the service address differs from the billing address, the old carrier rejects the request and the clock restarts. Dig up the actual bill before you start.
Three classic failure modes. First, the mismatch problem above: rejections over paperwork details are the most common delay. Second, the dead-line trap: if you cancel the old service before the port completes, the number can be released back into the numbering pool and lost to you permanently. Never cancel first. Third, the quiet period: during the cutover window, which can last hours, incoming faxes can vanish into the gap between carriers. Tell your regular senders you are switching, and ask anyone expecting something urgent to hold off for a day.
There is also a category of numbers that simply cannot port: disconnected numbers, numbers tied to a carrier that no longer exists in that rate center, and some virtual or app-issued numbers whose terms never included portability. If a number was free and instant, check the fine print before assuming you own it.
Yes, number portability applies in Canada too, and the process looks the same: new provider initiates, Letter of Authorization, keep the old line live until cutover. The practical wrinkle is that Canada's porting is coordinated through the carriers directly rather than a single national database, so timelines vary more by carrier pair. Ports between two large carriers tend to move fastest; ports involving a small regional carrier or a legacy landline provider take longer.
Honest answer: it depends on how many people fax you. If the number is printed on forms, business cards, and a website, porting is worth the hassle. If it is a machine in the back room that three vendors use, getting a fresh number from the new provider and emailing those three vendors is faster and free of risk. And if you only ever send faxes and never receive them, you may not need a fax number at all: LetterAgent, for example, sends outbound faxes to US and Canadian numbers without issuing you any number of your own.
Ready to fax it? Fax with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is sent.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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