Test fax numbers from HP and Canon, and what a test proves

A test fax is one page sent to a number that answers as a fax machine. HP and Canon each publish a test line that faxes a page back to you. A page coming back shows that your machine sends and receives on that line. It says nothing about the number you need to reach next.

Below are both lines as their makers state them, and what a test shows when you own no machine at all.

You can send a fax online as a test on this site: one document, one card payment and no subscription. The price is in the box above.

What does a test fax prove?

A test to a line that replies shows four things about your own side.

• Your machine dials out, and the line carries a fax call.
• Your page was scanned and sent, and the far end confirmed it.
• Your machine answers a fax call and prints what arrives.
• The fax number stored in your machine is right, because the reply is sent to that number.

It leaves four things open.

• Whether your recipient's number is a working fax line.
• Whether a long or dense document gets through. A test is one page.
• Whether a call to another country gets through.
• Whether a person reads what you send.

Which makers publish a test fax number?

We list a line only when the maker's own support page states it on the day we check. Both rows were read on 2026-11-13.

Maker	Number on the page	What comes back	Wait the page gives
HP	1-888-HPFaxme (1-888-473-2963 U.S.)	a return fax to the number in your fax header	5 to 7 minutes
Canon	1-855-FX-CANON (1-855-392-2666)	a test page to the fax number programmed into your machine	generally 2 to 3 minutes

The HP line

HP's page is Test fax setup with the HP Fax Test Service. It shows no date. This is what it tells you to do.

1. Create a one page black and white test fax.
2. Put your full ten digit fax number in the fax header. It has to match the phone line connected to the fax.
3. Send the fax to the number in the table.
4. Wait 5 to 7 minutes for the return fax.

If no fax arrives after 10 minutes, the page says to check the fax settings and try again. It also says that pressing *82 before the number unblocks caller ID "in most areas".

HP writes that it uses a received fax only to send the return fax. Faxes are stored in digital form for a time and then destroyed.

The Canon line

Canon's article is How to Test the Send and Receive Functions for Faxing, dated Mar 24, 2026. It has three steps. Program your full ten digit fax number into the machine. Send a test fax to the number in the table. Wait for the test page, which "generally takes 2 to 3 minutes".

Canon's one page PDF, Testing Your Fax Machine, gives the same steps and carries no date. We have not faxed Canon's line.

What is not in the table

Both pages are written for the maker's own printers. Neither says which other machines or services the line accepts.

Other test numbers appear on forums and on lists compiled by third parties. We looked for one more maker's line. We could not confirm it on that maker's own pages on 2026-11-13, so it is not here.

What happened when we faxed HP's line?

We sent a one page fax from our send page to +1 888 473 2963. The carrier reported it delivered on 2026-11-12. We did not see a reply.

HP's page explains why a reply would not reach the sender. The service sends its return fax to the number in the fax header. A fax from our send page goes out from our shared sender number. A one-time order has no fax number of its own and receives nothing.

So a test line tells an online sender less than it tells a machine owner. The carrier's delivery report is the evidence, and no page comes back.

How do you test without a maker's line?

You need a second fax number and someone who can look at what arrives.

1. Send one page to the second number. Use the same type size as your real document.
2. Read the confirmation page on your side.
3. Ask the person at the other end to count the pages and read a line of small print back to you.
4. Ask them to fax one page back. That tests receiving.

The second number can be a second line of your own. It can be a colleague's machine or an office you can call. It can be a number rented from an online fax service, where your page arrives as a file. Our own fax numbers are ordered through the API, so they suit software better than a single test.

Small print is worth testing. Our simulation of the smallest font that survives a fax shows which sizes software could still read.

If you are testing code and no machine is involved, use the sandbox. Sends made with a test API key go to numbers that act out each outcome. Nothing leaves the sandbox and nothing is charged.

How do you read a confirmation page?

The labels differ from machine to machine. Look for four things.

• The result. OK means the receiving machine confirmed the pages. Busy, no answer or an error code means it did not.
• The page count. It should match your document, with the cover sheet if you sent one.
• The number dialed. Compare it with the recipient's number digit by digit.
• The remote ID. The receiving machine can send its own number back during the call.

That last signal is optional in ITU-T T.30, as our glossary entry on CSID explains. A blank or odd remote ID is no failure.

A receipt from an online service carries the same facts in other words. Ours shows what the carrier reported: the provider reference, the pages confirmed and the completion time.

A clean confirmation is still the machine's word only. It does not show that a person read the page. Our guide to sending a fax covers what to do when the result is busy or no answer.