Your fax number is almost always the phone line connected to your machine. The fastest way to confirm it: send a test fax to any phone with caller ID — the number that shows up as the sender is your fax number. If you use an online fax service, it’s listed right in your account. That’s the short answer; below are the exact steps for a machine, a printer, and an online service.
The fastest way: send a test fax
If you only need the answer once and don’t want to dig through menus, this takes under a minute:
- From your fax machine, send a one-page fax to a mobile or landline that has caller ID.
- Check the caller ID on the receiving phone — the number shown is your fax number.
- No second phone handy? Look at the header line printed across the top of any fax you’ve already sent. The sending fax number is usually printed there — see fax number formats if you’re unsure what you’re looking at.
Finding it on a fax machine or printer
Most machines store the number under a settings menu. Power the device on and check the display or control panel first — some models show the number on the home screen or as a greeting. If it isn’t there, open the menu and look for a section called Fax Settings, Fax Setup, or Station ID. The number is typically saved as Own Number, Fax Header, or Station ID. (New to the hardware? Our guide on how to use a fax machine walks through the basics.)
One catch: if the number was never entered when the machine was installed, these fields can be blank. In that case the fax number is simply the phone line plugged into the device — check the line itself, or use the test-fax method above.
The exact menu path varies by brand. Here’s where to look on the most common ones:
HP printers
Open the printer menu on the touchscreen or control panel and look under Setup → Fax Setup for the stored Station ID or header number. If it’s unset, the fax number is the phone line connected to the printer.
Brother printers
Look under Menu → Fax → Setup (or Station ID) for the saved number. Brother machines also print the sending number in the header of outgoing pages, so an already-sent fax will show it.
Canon printers
Check Device Settings or Fax Settings on the control panel for the stored fax number (sometimes labeled Sender ID). If nothing is saved, it’s the landline connected to the machine.
Epson printers
Open Settings → Fax Settings → Basic Settings and look for the header or Your Phone Number field. As with the others, an unset field means the number is just the connected phone line.
Finding it in an online fax service or app
If you fax from an app or web service, there’s nothing to hunt for — your number is shown in your account at all times. In Municorn Fax, for example, it sits at the top of the app interface, on every device. For accounts with more than one line, each number is listed in the account details, with the main sending number marked separately from receiving numbers.
This is the practical advantage of online faxing: the number never goes missing, you can read it from any device, and you don’t need to power up a machine to check it. If you’re setting up faxing from scratch, an online number is the simplest to keep track of — here’s how to get a fax number online, and how to fax from your computer once you have one.
Looking up someone else’s fax number
Searching for a fax number that isn’t yours is a different task, and worth being honest about: there’s no reliable free reverse directory for fax numbers the way there is for phone numbers. Your best options are the number published on the recipient’s website or letterhead, or simply asking them directly. To find your own number, use the steps above.
Frequently asked questions
How do I tell my fax number from my voice number on a shared line?
If a single line handles both voice and fax, the numbers are the same. If you have a dedicated fax line or a distinctive-ring service, send a test fax to a caller-ID phone to confirm which number the fax goes out on. If you’d rather not deal with a shared line at all, you can fax without a fax machine using an app instead.
What if the fax number field is blank?
A blank Station ID or header usually means the number was never entered during setup. The fax number is still the phone line connected to the machine — check that line, or use the test-fax method to read it directly.
Can I look up a fax number for free?
To find your own number, yes — the test-fax method costs nothing and works instantly. For someone else’s number, there’s no dependable free lookup service; check their published contact details or ask them.
How do I verify a fax number works?
Send a short test fax and watch for the confirmation report. A delivered status confirms the number is active and reachable. Online services like Municorn Fax show send status and a timestamped receipt for every fax.
