LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > Do I need a fax number to send?
No. You only need your own fax number if you want to receive faxes. Sending a fax needs just two things: the recipient's fax number and a way to transmit, such as a fax machine, an online fax service, or an AI assistant that sends faxes for you. LetterAgent's fax is outbound only, so you never need a number of your own to use it.
A fax number is really just a phone number that a fax machine answers. To receive, you need a line that is listening: that is what the number is for. To send, you are the one placing the call, so you need the other party's number, not your own. It works the same way as a phone call: you need someone's number to call them, but you do not need your own number printed on a business card to place the call. When you send through an online service, the call goes out from the service's lines, and the recipient's machine shows the service's caller ID, not yours.
Put your phone number and email, and leave the "from fax" field blank. The number on a cover sheet is just text: it does not have to be a real working line, and nothing verifies it. What matters is that the recipient can reach you back, so a phone number and email address do the job better than a fax number would. One caution: some offices have their machines set to reject calls with blocked or unknown caller IDs, and faxes sent from online services can arrive that way. If a fax to a particular office keeps failing, ask the recipient whether their machine screens unknown callers.
| Sending a fax | Receiving a fax | |
|---|---|---|
| Your own fax number | Not needed | Required: a line that listens for incoming calls |
| What you must have | The recipient's fax number | A machine or service watching the line |
| What the other side sees | The sender's caller ID (often the service's number) | Your fax number, printed on your cover sheet |
| How replies come back | By phone or email, from your cover sheet | To your fax number |
When the conversation goes both ways. A doctor's office faxing you back lab results, a client returning a signed contract, a government agency acknowledging your filing: all of those need somewhere to send to. If you only ever send documents out and receive replies by phone or email, a fax number buys you nothing. Businesses that want one without a machine can get a virtual fax number from an online service, which delivers incoming faxes to email, but that is a receiving tool, and it is a separate product from sending.
LetterAgent's fax is outbound only: you describe the fax to your AI assistant, get a per-fax quote with the page count verified, approve the exact total, pay once, and it is sent to a US or Canadian fax number. You never get a fax number, and you never need one, because nothing comes back through the fax channel. If someone needs to reply, put your phone number and email on the cover sheet. One honest limitation: since there is no inbound fax, LetterAgent is not the right tool if you need a number people can fax back to. Fax is in private testing right now.
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.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com