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Temporary fax numbers that receive faxes for a short window, often minutes to a few hours, then expire. They exist for one-off situations where you need to receive a fax but do not want to hand out your real number. Up front: LetterAgent sends faxes but cannot receive them, so it does not offer disposable or any other fax numbers.
Behind the scenes they are ordinary hosted fax numbers drawn from a pool. The provider assigns you one for a fixed period, routes anything it receives to a temporary inbox tied to your session, and then returns the number to the pool when time runs out. Because the provider already owns the pool of numbers, there is no porting, no setup, and no commitment: the whole product is the absence of friction.
The trade-off for that convenience is ephemerality. There is no voicemail-style storage waiting for you later, no forwarding to a permanent address, and usually no way to extend the window once it closes. If the sender's fax arrives five minutes after expiry, it is gone. For anything where timing is uncertain, a disposable number is the wrong tool.
The honest use cases are narrow but real: a form that insists on a fax-back number for a one-time transaction, a vendor who will only send a document by fax, a signup flow that demands a fax number you will never use again. In each case the alternative is worse: giving out your permanent number to someone you will never hear from again, or signing up for a monthly fax service for a single document.
| Situation | Disposable number a good fit? |
|---|---|
| One-time form that must be faxed back today | Yes: the classic use case |
| A vendor who only communicates by fax, ongoing | No: get a permanent hosted number instead |
| Receiving something sensitive (medical, legal, financial) | No: see the privacy section below |
| Testing whether your outbound faxing works | Sometimes: fax yourself and check the received file |
| Someone needs to reach you by fax next week | No: the number will be long gone |
This is the part to take seriously. A disposable fax number means your documents pass through a provider you have no relationship with, sit in a temporary inbox you do not control, and may persist in that provider's logs after your window closes. For a restaurant menu or a blank form, none of that matters. For medical records, legal filings, or anything with account numbers on it, it matters a lot.
Two specific risks. First, number recycling: your "disposable" number goes back into the pool, and the next person assigned it could receive faxes meant for you if a sender dials it late. Second, the inbox itself: many disposable services display received faxes on a public or semi-public web page keyed to the number, which is fine until the document contains something you would not post on a bulletin board. If the document is sensitive, use a proper hosted fax number with a private inbox, or ask the sender for an alternative like secure upload.
Receiving faxes on a temporary number is legal; the number is a real, working number for as long as you hold it. What is not legal is unchanged by the number being temporary: junk-fax rules still apply to anyone sending you unsolicited fax ads, and using a disposable number does not exempt the sender. The disposability protects your privacy going forward, not anyone's behavior in the past.
A permanent hosted fax number from an online fax provider: a number that is yours month to month, with received faxes delivered to a private email inbox or app. It costs a small monthly fee and it solves every problem a disposable number has: no expiry, no recycling risk, a private inbox, and a number you can print on forms with confidence. For sending rather than receiving, you do not need any number at all: LetterAgent's fax flow (currently in testing) sends outbound faxes to US and Canadian numbers with per-fax pricing, no number issued to you, nothing to maintain.
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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