Fax and the mobile phone

Your phone can send a fax. It cannot be the machine that takes one.

"Fax and mobile" hides two questions with opposite answers. Sending a fax from your smartphone works perfectly well: the phone is only a screen for filling in the FaxTelecom form and attaching the PDF, while the call itself leaves from our platform. Faxing to a mobile number, on the other hand, is impossible with any provider. A transmission needs a fax machine at the far end that picks up and negotiates in audio tones; a mobile rings a person, and the cellular network distorts those tones on the way. That is why FaxTelecom only accepts landline numbers.

Why a cellular network can't carry a fax

Every transmission opens with a standardised exchange of whistles: a calling tone from the sender, an answer tone from the receiver, then a swap of capabilities such as resolution, speed and paper size. If nothing comes back within roughly thirty seconds, the sender hangs up. A smartphone returns none of those tones; it just buzzes in its owner's pocket.

Now picture a fax machine somehow connected behind a SIM card. The call would run through voice codecs (AMR, EVS) that keep only what makes speech understandable. The loss is inaudible to a listener. To a modem, which encodes data in the phase and amplitude of the signal, it is a stream of errors that drops the link within seconds.

Landline networks that moved to IP hit the same wall and got round it with the T.38 standard, which carries the fax data instead of its sound. Mobile operators do not offer it on consumer plans, so the ordinary voice call remains the only route, and it is the wrong one.

Three situations, three answers

When someone searches for "fax mobile", they are almost always after one of these three things.

  • You have a smartphone and a document to fax

    No obstacle at all. Open FaxTelecom in Safari, Chrome or Firefox, attach the PDF from your files and enter the fax machine's number. The line used is ours, so nothing comes off your plan, there is no app to install, and a one-page document goes free of charge.

  • Your recipient has no landline

    If they only own a mobile, they do not own a fax machine. No point trying: send them the PDF by email or through a messaging app. Fax keeps its value for organisations, practices and public offices equipped to receive it.

  • You want to read your faxes on your phone

    Then you need a virtual fax number rented from a specialist provider: it takes in the faxes and forwards them to you as attachments. FaxTelecom focuses on sending and assigns no numbers; our page on receiving faxes sets out the available options.

What the form checks

Before anything is transmitted, FaxTelecom checks that the number matches the landline format of the chosen country. In France, for instance, a number starting 06 or 07 is turned away with a clear message, before you even reach the confirmation step. The filter has one known blind spot: in Canada, landlines and mobiles share the same area codes, so no automatic check can tell them apart. There, ask your recipient to confirm the number belongs to a fax machine.

This block works in your favour. Without it, the send would fail after several retries, or ring a stranger's phone with a burst of whistling. An instant refusal beats the false impression that your document has gone out.

Your questions about fax and mobiles

Some websites claim to fax a mobile. How do they do it?
They don't fax at all: they usually send a text message with a download link. The recipient needs a smartphone, has to open the link and agree to download the file. No fax machine is involved, and no transmission report is produced.
Can WhatsApp or a text message replace a fax?
For getting a document to a private person, yes, and it is often the simplest way. But they are not faxes: no confirmation comes from the recipient's device, and many organisations will not accept documents that arrive through a messaging app.
How do I fax from an iPhone or an Android phone?
Through the browser, with nothing to install. On FaxTelecom, fill in the form, attach your PDF (up to 100 MB) and submit. A confirmation email follows: tap its link within 3 minutes, then watch the transmission live from the same phone.
How can I spot a mobile number abroad?
Each country keeps its own prefixes for mobiles: 06 and 07 in France, 015 to 017 in Germany, 04 in Belgium, 3 in Italy. Our international dialling code directory shows the expected format for every destination; for Canada, only confirmation from the recipient settles it.

Fax in practice

In this section

Where to go next

Hand-picked pages to help you prepare, send or prove your fax.

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