An online fax number is an ordinary phone number. What makes it a fax number is whatever answers the call. For decades that was a machine on a desk. With online fax, a server picks up and the pages reach you as a PDF you can open in your browser. The sender’s machine can’t tell the difference.
How a fax call works
The phone network treats a fax number like any voice number. When a fax machine dials, it plays a short repeating beep that says a fax is calling. If a person answers, they hear beeps and the call fails. If a fax device answers, it replies with a high steady tone and the two machines start talking.
They follow an old standard called T.30. The receiver lists what it can handle, and the sender picks a speed both sides support. The sender turns each page into black and white dots and sends them down the line as sound. After each page the receiver confirms it came through, and at the end both sides hang up.
How an online fax number answers
With online fax, the number connects to a carrier or fax provider. Software answers the call and plays the part of a fax machine, going through the same handshake a desk machine would.
The server receives the same page images a desk machine would print. It saves them as a PDF instead, so you can open the fax on any phone or computer without special software.
On StillFaxing.com, each fax shows up on your number’s page, and you get an email with a link to download it as a PDF. Faxes are encrypted shortly after receipt and deleted 7 days after they arrive, so download anything you want to keep.
Sending works in reverse. Upload a PDF, PNG or JPEG on your number’s page, enter a fax number and press Send fax. The server dials out and sends it from your number with a StillFaxing.com cover page, so replies come back to your number. Free numbers send 2 faxes, up to 20 pages in total.
Why a fax number can be temporary
Most fax services rent numbers from carriers and give you one for as long as you pay. A temporary number works because a call only needs a server listening at that moment.
StillFaxing.com lends you a number for 4 hours and only asks for an email address. You can add more time from the number’s page before it runs out.
When your time is up, the number goes back to the pool. A fax sent after that may not reach you. Numbers are reused, and each one rests between borrowers so faxes meant for the last borrower die down before you get it. You can’t keep the number or move it to another provider.
To get a number now, follow how to receive a fax online.