Why is there no true smartphone faxing app?

This is really puzzling me.

There are a huge number of folks with smartphones today, obviously. And there are faxing apps for those smartphones. As far as I can tell, though, none of them are actually using the phone to fax. Instead, you buy credits or pay a per-page fee, and the company that makes the fax app receives your document via the data connection and faxes it via some other method.

But why? Fax modems have been available for about 30 years, so the technology for a computer to translate a page from MS Word into fax tones is well established. As I recall, you’d basically choose “fax modem” as your printer and just “print” the page. Well, smartphones can talk to printers too, nowadays. And your phone is…a phone. So there’s a communication line right there. I don’t see any reason why you can’t send a fax to a land-line-connected fax machine directly from your smartphone itself.

Given all of this, why is there not a true faxing app for smartphones? Is there some technical hurdle I don’t know about?

Note: I know that, with email and the ability to send pictures by text, the need for faxing is going the way of the dodo. But there are some businesses, and particularly government offices, that are hard to contact any other way. So, yeah, I know it’s practically obsolete, but I’m wondering why some enterprising programmer hasn’t tried to make a few bucks by making a faxing app.

Perhaps because normally when you send a fax, you’re transmitting an image of a printed page. So what would you be sending via fax on a smartphone?

You can’t fax through a mobile phone connection. There’s no dial tone and fax handshaking does not work via mobile phone networks. You need a land line.

Why does faxing even exist anymore when scanning and emailing does the same thing but with no need for expensive special purpose equipment and phone lines?

Dial tone is just electronic noise and can easily be replicated. If you hold a phone up to a recording of a phone being dialed, your phone will dial (does not work for POTS, of course).

And yet, digital cellular networks don’t support fax tones.

Are you sure? I can think of reasons why this might be true, but I also have seen weird hacks where people used a mobile phone and an old dialup modem with an acoustic coupler to make a modem connection (and fax connections aren’t very different)

I’ve wondered this too, but some people (lawyers and government agencies, for example) don’t give out email addresses for privacy reasons, so they still communicate by fax.

Bolding mine. That is your answer right there. Developers have no incentive to create a way for you to send free faxes.

Were they doing it with older analog cellular networks or the current all digital ones?

Phones can hold documents of all sorts, PDFs, and of course photos. If cell phones could fax: say I have to sign something and fax it back, I can sign it and use my phone to snap a picture of it, have GeniusScan+ convert it to a nice looking document, and then fax it right back.

I’ve done some quick searching and reading on the handshaking issue, and found some information on faxing over VoIP lines that seems like it might be talking about the same problems a cell phone might have. It still seems like an issue that could be overcome, though. I suppose there’s just not much interest.

^This.

Faxes should die a quick death. What the hell are we still using this 174-year-old technology for?

Not really sure - on second look, a lot of the experimentation I thought I had seen turns out to be somewhat theoretical in nature.

I can certainly see why compression could limit the fidelity of fax tones, and the packet-based nature of transmission could certainly mess up the timings - is that what you meant?

FAX is analog, as far as the modems inside a FAX machine.

Moden cell phones are 100% digital
So to start with, i think you would need an DAC some place to convert back to analog so the FAX machine can receive.
But since the FAX machine does need to talk back to the sender, i guess you need an ADAC too?

MODEMs do not fair well with multiple conversion in the signal path, and in this modern age, that is a lot of money to step backwards and use 1980’s tech to send a TIFF image, when email is faster and you can send direct doc formats in lovely universal formats like pdf doc rtf and xps etc.

Even 2G is faster than the average 9600 baud speed of a fax machine.

A better question is why do so many large organizations now days still rely on FAX technology when more robust and cheaper methods are easily and readily available?

There shouldn’t be any technological reason why a service like Rightfax or Wirefast wouldn’t be able to write a smartphone app that would take pictures of a sheet of paper and use a centralized “cloud” gateway to send the image via fax. There just doesn’t seem to be any financially viable reason to do so.

Suppose that I sent a fax using an old-fashioned fax machine, except that I misdialed the number, and accidentally called an ordinary phone line. The person who picked up the phone would hear a bunch of electronic chirps and beeps, right?

And now suppose that, instead of a person picking up the phone, it was an answering machine. I would now have a recording of those electronic chirps and beeps, right?

And if I then called up the number of a fax machine and played that recording of chirps and beeps, the fax machine would print out a page, wouldn’t it?

And I can call up a landline with a cell phone, even though they use different systems, and still make the landline produce sounds, can’t I?

And a computer program could, of course, generate a sound recording of the appropriate chirps and beeps, couldn’t it?

So if we put this all together, what happens if a cell phone produces a sound file of the appropriate sounds, calls up the number of a fax machine, and then plays that sound file over the sound connection?

And yes, faxes should die off now that better options are available. But the point is, they haven’t: Some offices still insist on fax for some purposes, and many people are still forced to do business of various sorts with those offices.

It seems as tho you’ve answered your own question.

I don’t think so - there’s a handshaking process - the page doesn’t transmit until the receiving fax acknowledges it’s OK to receive.

I take it you know about eFax, right? Both the app and the website let you take some random document and fax it to some random number. They have per-page and/or per-month prices. (Sorry if that’s obvious, just making sure we’re on the same page).

Now as for why your cell phone itself can’t make a fax call (or a dialup modem connection), basically, they don’t transmit the full spectrum of sound that old copper lines used to. This was already somewhat the case back in the CDMA days, now it’s even more so in the era of VOIP where everything is pre-compressed, sent as data, and then recombined into voice. Those codecs were meant to send human conversational voice as cheaply as possible (in terms of bandwidth), which is also why they tend to sound like crap compared to copper lines and why music and other sounds (including fax and data modem communications) don’t make it through with full fidelity. More info here: Faxing over VoIP, the correct configuration settings that you need to make.

There are workarounds like this: http://ieeexplore.ieee.org/document/4383352/?reload=true&tp=&arnumber=4383352&url=http:%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4383352 but that requires special software or equipment on both ends. It converts modem sounds into human speech frequencies and sampling rates and back again, sending it over cell phone voice codecs. But that’s totes cray cray when you can easily get megabit speeds on all the major carriers and just send it as a picture =/

Faxing over cell phone: Picture -> recompression and dithering into black and white -> anticipate and correct for upcoming voice-centric codec -> compressed by codec -> go through network and be subject to packet loss and error correction not designed for your fax -> reach destination in pieces -> decoded by codec -> hope that error-checking wasn’t too severe and/or you didn’t lose too many packets -> VOIP connected to POTS -> analog telephony adapter or some sort of software, maybe using something like T38 -> fax machine that hopefully isn’t too confused

Faxing over POTS: fax machine -> scan and compress -> modem -> other fax machine
Or in the modern era: picture -> file transfer over internet using standard protocols -> other smartphone

TLDR: VOIP and cell phones don’t transmit the same frequency spread that old copper lines used to. At some point somebody has to pay for a POTS line and use special equipment or software to convert your cell phone fax into the old-school style signal. You can do this cheaply using a dial-up modem and a PC (or even one connected to your smartphone) but you would still have to pay for a POTS copper line, which by itself would already be more than a typical eFax subscription.

I know a guy who does not know how to type, at least not at an acceptable speed. No, he’s not really old. He finds it faster to write something (including figures, formulas, etc) down on a piece of paper, stick the pages in a fax machine, dial my number, and hit send. Not obsolete.