Modem sound autopsy

What you're hearing is the way 20th century technology tunneled through a 19th century network:

What you're hearing is how a network designed to send the noises made by your muscles as they pushed around air came to transmit anything, or the almost-anything that can be coded in 0s and 1s.

The frequencies of the modem's sounds represent parameters for further communication. In the early going, for example, the modem that's been dialed up will play a note that says, "I can go this fast." As a wonderful old 1997 website explained, "Depending on the speed the modem is trying to talk at, this tone will have a different pitch."

That is to say, the sounds weren't a sign that data was being transferred: they were the data being transferred. This noise was the analog world being bridged by the digital. If you are old enough to remember it, you still knew a world that was analog-first.

I used to spend afternoons trying to whistle lines of specific ASCII characters into the 110 baud analog coupler on the teletype. My inability to do this very well made me realize I was probably not cut out to be a singer. Oh, and also, the fact that I was trying to do this at all. For some reason, ampersands were easiest.

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32 Responses:

  1. acb says:

    It boggles the mind that one might reasonably expect people born after a certain time to think that the sound was merely an indicator of data being transmitted, a cosmetic piece of UI rather than the actual mechanics of communication.

    • chris t says:

      Seriously. I mean, sure, affordances and skeuomorphs and all that -- I can see some kind of indication being necessary to the user so that they know the machine's working. But why make it so face-meltingly unpleasant?

      Although the tones for "Your call cannot be completed as dialed" would curdle milk and enrage dogs, so maybe "sadism" was an acceptable response.

  2. I used to be able to convince 300 baud modems to handshake with me by whistling, but I could never get any repeatable characters.

    (...and I wondered why, as a 13-year-old, girls didn't like me more...)

    • gryazi says:

      I got a complaint about this for fucking around with the local sysop's system too much. (Sorry Vicki!)

  3. AutoJack says:

    My boss's cell phone ring tone is a modem handshake sequence. There was a flurry of bets and counter-bets one lunchtime, soon after he started, surrounding whether our youngest engineer (23 maybe?) would be able to identify it. He did, easily, and then proceeded to heap scorn on us old-timers for thinking he was some kind of baby. Later we tried it on our intern, who was 20. He identified it, but couldn't specify what speed it was - I think he had only ever heard 56k modems. So now we figure it's only a matter of time before we hire someone who has no idea. I figure broadband internet in the home didn't become commonplace until at least 2000, so perhaps many of today's 10 year olds have never heard a modem, but it will still be awhile before any of us are employing them : )

  4. AutoJack says:

    I just realized that modem sounds of a sort are still a near-daily part of my life. As a ham radio operator, I use a digital mode called PSK31 all the time. It's 31 baud, which finally allows me to trump all my smarmy older friends who used to give me grief about starting off with a 2400 bps modem. Admittedly it doesn't feel so painfully slow when you're only using it to chat at keyboard speed with someone, rather than trying to download the latest Giffy Girls images. When I mention digital modes to non-hams, I usually explain it by saying, "It's like a modem, only it uses radio for the transport." Communication in this way gives a much more concrete meaning to the word "bandwidth."

  5. Nathan Roberts says:

    The nerd in me was hoping for a more detailed breakdown of the tones, and a comparison between the different baud rates.

    Which would also explain why it takes almost a full minute for a 56k modem to connect, when it took a 2400 modem 5 seconds back in the day.

    • Nathan Roberts says:

      Actually, now that I've checked out the "Wonderful old 1997 website", that answered a lot of the questions I had. It doesn't seem to say anything about modems faster than 28.8 though. The site probably predates them.

    • I have an impression and I don't know if it's accurate - do the modems recapitulate the history of modem speeds while they handshake? Like, do they start at 300, and negotiate about whether to jump to 600, where they negotiate about 1200, etc?

      • Nathan Roberts says:

        The Wo97W seems to imply that they do, though it's not clear whether it goes through the possibilities linearly, or just emits all the possible frequencies at once and sees what the other side answers to.

        Next, the modems will query each other about their capabilities. This is done by adding carriers. The Answer will add all carriers it can; in the case of a 9600 modem 3, in the case of a 28,800 modem 11. Originate will hear this and answer with all carriers it knows. In some protocols, this is heard as a series of beeps going from low to high, in some others it just appears there is another burst of static.

        Carriers that remain unanswered will be dropped. A 14.4 modem for example, dialing into a 28.8 modem, will only recognize and answer the 14.4 carriers. The 28.8 modem will drop the rest and they will start talking at 14.4.

        So it sounds like they actually negotiate all possible speeds all at once, rather than one after the other.

        • Nathan Roberts says:

          Aaaand just pretend that that last sentence of mine isn't actually there, and didn't get left in due to sloppy editing.

          (That was my original conclusion, but after re-reading the 'series of beeps going from low to high' part I decided it could go either way.)

  6. gryazi says:

    Also, it boggles the mind that faxes (yeah, there's plenty of "Previously"... for that) are still forced to do this, probably mostly over VoIP links these days which also kill throughput. (But at least our service still charges by the minute yet also still comes out cheaper by yearly average than paying for unlimited.)

    I notice "Internet Fax" has been a feature on Enterprisey hardware since 2000 or so. However clearly the universe doesn't understand how that works or if it's standardized, and I haven't dug deeper.

    "Scan to email" appliance features are almost successfully replacing it, finally, with the same UI advantage (pop dead-tree documents in hopper, walk away vs. 'mess with actual desktop software') but with the caveat that you can only really confirm transmission to your relay (if you're lucky), not the end-recipient [although I do envy the MS-only world where the 'return receipt' feature is actually trusted, sometimes; this is also codified by some fax-replacing court rules here which don't completely understand that it's entirely optional at the mercy of the recipient].

    It seems like paper will actually be dead for new documents before we get this re-standardized effectively. (But there will still be plenty of old documents around for a century or twelve, when it comes to things like DNA's zoning nightmares.)

    • phuzz says:

      Yup, our fax at work scans an analogue page, transcodes to digital, turns it back into analogue to send down a phoneline to an ATA that turns it back to digital for our VoIP system, through to an ISDN line that (still digital I think), and potentially the same palava at the other end. Incoming faxes are sent straight to email.
      The thing that gets me is that basically every fax we receive is some kind of print-out from a computer anyway, SO WHY NOT JUST FUCKING EMAIL IT?

      Back on topic, step one of trouble shooting a borked fax is to turn on the speaker and listen to see what it's doing, always amusing when a user is cursing that the fax is broken and not sending, to turn the tone on and hear the nice BT lady saying "We're sorry, the number you have dialled is not recognised"

      • jwz says:

        The thing that gets me is that basically every fax we receive is some kind of print-out from a computer anyway, SO WHY NOT JUST FUCKING EMAIL IT?

        Because you still have a fax machine. Because you still do not say to people the words, "I do not have a fax machine, email it."

        My business no longer has a fax machine. It's fine.

        • phuzz says:

          I have asked to unplug it, but been told "No, our customers still use it". Admittedly it doesn't cost us anything really, bar a few hours of my time to maintain it, and the extra few watts for the power for the ATA, but it does annoy me that it still exists.
          Worse, because the accounts department have a separate fax number, I have an old multifunction printer in the server room, which is solely powered on to translate faxes to email.

          Mind you, we are getting a new phone system soon*, so maybe I can find one with a built in fax gateway.

          *(suggestions of VoIP systems for a small company of about 40 employees are welcomed, as long as our gracious host doesn't mind, we're going from a Cisco Callmanager 4 system which is bloody horrible.)

          • jwz says:

            That's my point. Your customers only still use it because you have it. If you didn't have it, they would email you instead.

            • phuzz says:

              I fully agree, but I'm just the IT guy. Also, our customers are just as backwards my managers, and I'm told my suggestion of "fuck it if they can't take a joke" doesn't meet my companies standards for customer communication :p

            • gryazi says:

              My excuse, of course, is that I work in an industry that interfaces with The Government.

              Although The Government is actually fairly digital these days. It's mainly The Banks and The Employers who demand to see grainy scans of actual ink signatures or actual actual ink signatures. And pausing to argue about it will just sink the clients into even deeper shit, since half the job [especially from the paralegal seat] is ascertaining everyone's stupid rules and complying with them to expedite things.

            • Employees don't, generally, get to make the sorts of (right) decisions that you do for your business, Jamie.

          • we use a 3rd party service that accepts faxes and then converts them into PNGs and emails them. I suspect that's a net-negative use of technology, but someone still thinks it's important.

          • Luke Lathrop says:

            it's kinda funny but you have the easy suggestion in your post already......*


            oh and call manager would do that for you to, it just costs money

  7. Nick Lamb says:

    For most people, today's world is still analogue first. Ultimately only the people doing quantum communication for key distribution are really working with digital data at the bare metal, everybody else modulates their data into some sort of (analogue) carrier signal and then demodulates it at the far end just like a modem did.

    The main thing that's "digital" about Digital Subscriber Line is the service agreement. With a voice line any fault that doesn't prevent a conversation isn't the phone company's problem. PPP drops every time a truck drives past? Too bad. With DSL it is their problem (though of course YMMV when it comes to actually getting them to actually fix anything).

    If you remove the filter, you can even hear (some of) the sound of DSL on your telephone. That's a lot easier these days because the filter is no longer installed in a sealed unit by an engineer, but just bought at the hardware store and plugged in by the end user. Of course unlike a 300 baud modem the DSL sounds are completely unintelligible so you won't be whistling along, and much of the "sound" is outside the frequency range of your hearing, but you can hear that it's basically no different than it was 30-40 years ago.

    (NB, doing this may drop the link. Do not attempt this experiment while other people are using your DSL connection unless you want to incur their wrath).

  8. Jason Spence says:

    Here's a breakdown of the V.34 handshake, others are elsewhere on this site:

  9. Lloyd says:

    Why do the soft phone buttons on my iphone make funny beeps? They don't need to.

    • Karl Shea says:

      They still need to make the DTMF tones because phone systems still use them. For example, dialing an extension on a PBX or entering your account number to check your bank balance.

      • Lloyd says:

        They don't need to beep to the user - only down the 'line'. And that is only when the call is active. They don't need to beep when typing in the number before placing the call. Feedback to the user is the typed number appearing, just as when typing at any other point - and if you're blind voiceover can tell you the number. This unnecessary beeping to the user is skeumorphic of the order of hearing a jukebox clunk before your selected music track plays, or hearing a recorded hard disk whirr as an app opens.

        • Because it's an expected UI component for the median user. No, it's not strictly necessary, but people are used to phones doing it. Why is it a problem for you?

          (Aside: I'd like to be able to specify the sounds emitted by the phone. Because I want to hear dial-phone clicks, not touch-tone beeps. But whatever.)

          • Lloyd says:

            People are used to LANDphones doing it. Mobile phones (feature phones, Nokia whatever) do NOT do it. No cordy, no beepy.

  10. Will says:

    The article does miss that the hard constraint on phone line bandwidth is not the 19th century analog network, but the mid-20th century switch to digital telephony (TDM), which constrains you, without compression, to 64 Kbit/s resolution per line. Once you throw the ulaw codec into the mix, getting 56Kb in and out is pretty impressive.

    • Olivier Galibert says:

      The "magic" of 56K modems is that the inter-node communication is digital. So the 56K analog part only happens between your modem and the nearest connection point. Faster modems on pure-analog links was 33K.

      It's pretty what ADSL is nowadays, analog fun to communicate the data only up the connection point where you jump onto real digital lines (for analog values of digital, because the world is analog, except when it's quantized).


  11. Alex says:

    You don't get to hear them warble, but I somehow love the fact that 20-odd Mbps HSPA dongles talk Hayes modem commands to your computer and sometimes you even need to wvdial them.