Everyone who used early telecommunications services, not to mention the early dial-up Internet services, is familiar with the tones and hissing sounds of a modem establishing a connection. I recall all my home computer modems, from the early 1980s 300 baud units through to the late 1990s 56K units all having speakers to provide this audible status/feedback during dialing and connecting. Indeed, it is one of the strongest memories surrounding telecommunications during those "pioneering" years.

But terminal programs were usually sophisticated enough to provide nice status indications (mainly visual, but possibly audible) about what was going on with the modem while trying to establish a connection. Such terminal UI features certainly seem superior to the horrendous "groaning" and "hissing" from the modem speaker.

So why were modem speakers such a persistent feature, and "fixture" of the time?

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    So you could hear the person at the other end saying "hello? hello?" when you misdialed the ISP number?
    – dave
    Commented Jul 22, 2019 at 16:36
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    Personally I never minded the sounds - it was an indication of how the handshake and baud rate negotiation was progressing and I recall a few occasions of their being problems that caused me to give up on the connection. Commented Jul 23, 2019 at 8:32
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    "But terminal programs were usually sophisticated enough to provide nice status indications" -- citation needed
    – JCRM
    Commented Jul 23, 2019 at 9:32
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    @NibblyPig Have a look at this blog post. The pure tones at the beginning of the handshake are basic protocol negotiation. The hissing is line quality measurement and wide-band digital data. Commented Jul 23, 2019 at 10:55
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    They had speakers because some of us knew what the sounds meant and found it convenient to be able to abort a connection attempt early when it was clear the line test wasn't going to give us the speed we knew we could get with another attempt or two. Also, it's the ultimate KISS debugging tool. Cheap, easy, effective.
    – J...
    Commented Jul 23, 2019 at 12:09

9 Answers 9


Much of this has been covered by previous answers, but to try to summarize:

  1. Adding a speaker was cheap and easy. The additional parts were standard, reliable, and inexpensive.

  2. It provided rich, immediate, understandable feedback on a variety of call-progress milestones.

Click -- modem is responding enough to grab the line. (This click was usually from a mechanical relay, not the speaker, but it goes into the same sensory-processing pipeline.)

Dial tone -- phone line is available. No dial tone? Check whether you're plugged in, see if your regular phone has been off-hook long enough for the phone company to give up on it. If you hear a voice, someone else is using the line; try again later.

Touch-tone/click signals -- you're dialing the remote number. If there are too many or two few digits, you'll hear the difference; eventually, you might even learn to recognize the patterns for frequently-called numbers, so you can hear if you've accidentally dialed the wrong one.

Remote ring -- you've successfully reached the remote number. Busy signal, disconnected-line message, "you must first dial 1"? All much easier for a human ear to interpret than for 1980s hardware.

Connect tones -- you've reached a modem at the other end. Voice or recorded message? You haven't reached a modem.

Silence following the previous stages -- the modem thinks you've connected successfully. Continuing connect/handshake tones? You might have a bad line; if it goes on too long, hang up manually and try again.

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    The click always sounded mechanical to me, I think you could hear it even if the modem was muted.
    – NibblyPig
    Commented Jul 23, 2019 at 8:57
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    Also: Connect tones/handshake noise sounded different than usual? (At least with the faster modems, repeated "doooong!-bzzzzz-doooong!-bzzzzz" were a classic for me; I believe that was the modem backing off and retrying.) Something's gone wrong with the handshake; by the second or third dong, you might as well abort and try again, because it's not going to succeed or, if it succeeds, the connection will be well suboptimal.
    – user
    Commented Jul 23, 2019 at 11:36
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    @NibblyPig Yes, the click was usually a relay. A solid-state switch (silent, no moving parts) capable of coping with phone-line voltages would have been quite expensive, and it probably would've made the modem harder and more expensive to certify.
    – jeffB
    Commented Jul 23, 2019 at 16:21
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    Even in the mid 80s, not all modems were multi-standard and a trained ear could distinguish between V.21 / V.22 / V.23. Had this with a business customer who couldn't get through to his bank any more - they had changed from V.22 to V.21 on the number he was using without informing him. He didn't believe me at first ...
    – grahamj42
    Commented Jul 23, 2019 at 23:30
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    In hindsight, the modem speaker is one of the most genius debug methods I've ever encountered on such a small piece of hardware.
    – Mast
    Commented Jul 24, 2019 at 8:28

Not all modems from back in the day had speakers, for example an early popular modem was the Hayes Micromodem II (available for Apple ][ and S-100 machines) and it did not have a speaker.

But the speaker served a few purposes that I can think of:

  1. Early modems were not very good at detecting various states, e.g. busy line, voice pickup, disconnected number notifications, etc. Without the modem supporting the detection of these states, the terminal program wouldn't do a very good job reporting it.
  2. You could quickly tell if the line was busy or if someone picked up the phone. Even with later modems, detecting voice was not quick or necessarily accurate.
  3. You could detect any dialing errors easier. Obviously, this would be more appropriate for complicated numbers rather than ones in your local area code / exchange.

Personally, I always left the speaker on though perhaps turned down low enough that I could hear the dial and busy tones. If anything, it did give me the ability to whistle a carrier tone by hearing it so many times :-)

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    On the first WebTV set-top boxes, the modem noise could be sent to the TV speakers, but was initially configured off. This made it hard to diagnose problems, so we bought a bunch of phone line monitors and battery-powered speakers from Radio Shack, and listened in that way. Once the people in charge of that decision discovered that it was also really hard for end users to debug connection problems without audio feedback, the modem noise was re-enabled. (It's tough enough to diagnose connection problems when they're calling customer service on the same phone line they use to dial the IAP...)
    – fadden
    Commented Jul 22, 2019 at 20:11
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    Regarding (1). My first job (1993) was writing software to talk to fax-modems (e.g. MultiTech MT3334ZDX). In fax mode, at least, British Telecom's recorded message along the lines of "This number is no longer in use" started with a drawn-out beep (presumably designed to alert humans that they weren't talking to real person). On many occasions, this was similar-enough to the first stage of a fax negotiation that the modem reported it had connected to a remote fax machine/modem. It would then fail to "negotiate a suitable speed", but made for some very misleading logs.
    – TripeHound
    Commented Jul 23, 2019 at 7:53
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    With the systems I used, there was also the option of leaving the speaker on until the connection was established, which let the user hear the interesting part, while not being a distraction during the connection
    – ilkkachu
    Commented Jul 23, 2019 at 10:18
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    About (1) I remember my 14.4K modem refusing to dial and emitting NO CARRIER because it didn't recognize the Italian dial tone. Several months later I discovered the ATX3 command and I could finally get to the Internet for the first time. Commented Jul 23, 2019 at 12:42
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    @JAB That's all very well in theory (and probably did work most of the time). The one "takeaway" of working with modems and 'phone systems is once you add the vagaries of analogue, PBX exchanges etc., nothing is ever that simple! Seen cases where a specific fax-modem refuses to talk to a specific number. A real fax machine (or a different brand of fax-modem) will happily talk to it from the same premises. The same brand (once or twice even the same physical modem) will happily talk to that number from a different location.
    – TripeHound
    Commented Jul 24, 2019 at 9:48

So why were modem speakers such a persistent feature, and "fixture" of the time?

Three basic reasons:

  1. Adding a simple amplifier and a speaker is the most easy way to handle unexpected situations
  2. In many countries/networks having a speaker active while establishing a connection was mandatory to make it legal/get a validation
  3. Adding it was as well the least cost intensive way to handle complex situations.

Keep in mind, the kind of modems most people used were not for dedicated lines, like today's cable or DSL installations, but operating over regular dial up. To start with, anything could happen - starting from some angry mom picking up the phone were her son has hooked up his BBS, wrong numbers, all the way to signal tones outside the spec the modem was built for (for example ring tones in various countries used different rhythms and frequencies).

So having a speaker was a quite good debugging tool - after all, whatever happened on a phone line would be within 3000 Hz, clearly noticeable by humans listening.

This is also the reason why phone regulators/companies required them to be installed as well. They wanted to minimize interruption of third parties (due to mishandled/directed calls) as well as having the user able to detect special situations on his own, without calling for service. In fact, in many cases it was required that each and every modem had to have a handset (or a complete phone) connected, so the operator can pick it up and talk to any (unintended) party on the other side to apologize and/or first talk to the other side before switching to data. In reality most private users ignored that part (as well).

These are the reasons why feeding the speaker, until a valid connection was established, was the default configuration - though, it wasn't really enforced. If you didn't like it, it could be configured away - at least with most modems.

Last but for sure not least: modem producers liked it as well. After all, with a speaker they didn't have to invest much money in detecting all kinds of situations. Let the user handle it like he was used to doing with a regular phone call.

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    Could you add an example of a county that required an active modem speaker? Not doubtful, just curious.
    – Kaz
    Commented Jul 22, 2019 at 17:59
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    Take Germany to start with.
    – Raffzahn
    Commented Jul 22, 2019 at 18:09
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    I've a feeling (but not in a position to double check) that the UK did. IIRC, for while fax machines similarly had to "sound" the dial/connect phase.
    – TripeHound
    Commented Jul 24, 2019 at 17:19
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    @TripeHound yes, in most countries fax machines were just seen as a device using a (built in) modem and had to apply to the same rules.
    – Raffzahn
    Commented Jul 24, 2019 at 18:27

I suspect it could be a holdover from the days when a modem was a box that connected between your terminal and your phone. The phone handset was used to dial the remote number; when you heard the whistle from the far modem, you'd press the 'online' button on the modem, and then replace the phone handset.

And, of course, if it wasn't a modem whistle you heard, it was either a confused human, or else some telephone-system signal telling you why you hadn't been connected (either tones or voice announcement).

So audible signals were an intrinsic part of knowing where you were in the connection sequence.

Image from _Handbook of Data Communications_, UK Post Office, 1975

The photo is from Handbook of Data Communications, UK Post Office, 1975. The modem's the box under the telephone.

I seem to recall that the PC-board modems could be configured to not enable the speaker, but I for one always left the audio on, for reassurance that things were progressing in the desired manner.

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    This is basically what I was going to answer. The old modems were called "acoustic" modems. You'd dial the number from the phone, listen in the handset for the tones, and then place the handset in the modem. So, people were used to hearing the tones as confirmation that they had dialed the right number.
    – DrSheldon
    Commented Jul 22, 2019 at 18:11
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    You're talking about acoustic couplers, but they're not "older" than wired modems. Acoustic couplers were merely the cheap option. The crucial thing was the need for manual dialing; the usually-dumb terminal couldn't do it, so you had to use the phone handset.
    – dave
    Commented Jul 22, 2019 at 21:11
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    @another-dave Correct that those were acoustic couplers. But the issue wasn't that the terminal was "dumb" - the problem is that the modem was "dumb". It wasn't until the Hayes Smartmodem that the problem was really solved - and the Smartmodem (and later clones) could be used easily with a dumb terminal, as I did for many years (TTY43 then Wyse 100). Commented Jul 22, 2019 at 22:24
  • Yeah, you're right. I was thinking about signaling, but the crucial lack is being able to dial.
    – dave
    Commented Jul 22, 2019 at 22:30
  • I don't know how fast GPO Modem No 1 was, but Modem No 2 was up to 200 bits per second. Bell System 202A was up to 1200 at the same time. Telecommunications and the Computer, Martin et al, Prentice Hall, 1976
    – Owain
    Commented Jul 23, 2019 at 19:07

All the answers above have concentrated on outgoing calls but modems also took incoming calls and, because phone lines were expensive, it was unusual to have multiple lines for fax, data, and voice.

Therefore the modem was usually installed in-line with the phone (i.e. the circuit came into the modem, and then continued onward to the handset).

Usually a modem would be set to answer after a set number of rings, allowing time for a human to pick up the phone. Moreover, the modem could be set to answer in quiet mode and not do negotiation until it heard a remote modem, so as not to fry the ears of a voice caller.

In this case, the speaker was very useful, as the caller would hear the cessation of ring-tone as the call was answered but no sound. They'd usually go "hello" or similar, and you could then pickup the handset and talk as usual.

  • Nice observation. I wanted to say something about incoming calls in my answer, but realized that I'd never actually taken an incoming call with any of my modems...!
    – jeffB
    Commented Jul 23, 2019 at 23:20
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    +1 for this as well -- modems weren't just for dialing ISPs (or BBSes) that had dedicated lines. It was not uncommon to directly dial your buddy's modem, and the speaker definitely helped you figure out when a human over at his place picked up the phone by mistake.
    – A C
    Commented Jul 24, 2019 at 1:46

On an older modem, if one tried to dial a number, one of two things would happen:

  1. Before a configurable timer expired, the modem received a carrier tone. In this case, it would output "CONNECT" and then start exchanging data with the far end.

  2. The timer expired without the modem having received a carrier tone. In this case, the modem would output "NO CARRIER".

Older modems had circuitry to detect the carrier tone, but not to detect anything else that might happen on the line, since a modem had no real reason to care about such things. All the modem cared about is whether the connection succeeded or failed. A human might want to know more, but the simplest way of giving such information to a human was to add a speaker.

BTW, I remember a modem which had a configuration option to mute the speaker as soon as it heard the carrier pilot tone, rather than at the end of negotiation; I don't know why that wasn't a more common option.

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    Actually, older modems didn't dial, you dialed manually. The "CONNECT" and "NO CARRIER" messages are from the Hayes Smartmodem (and many later clones). With older modems, your connection message was typically a login message from the remote system (provided it was smart enough to start a login process on DCD). Commented Jul 22, 2019 at 22:27
  • @manassehkatz: I've used modems where one would manually dial a telephone handset, but typically one would listen on the telephone handset to know when and how the far side answered. Older auto-dial modems behaved as I described, and needed a speaker because they lacked any other means of determining what was going on.
    – supercat
    Commented Jul 22, 2019 at 22:36

My guess is that's its mainly for easy human understandable notification.

Probably it can be compared a little bit with electrical cars. They do not make sound. Because people are not used to them, it can be dangerous if one suddenly approaches you (especially from a side you cannot see). To prevent this problem, some cars make sounds (like a motor) to 'warn' people there is a car near.

Of course this is more from a safety point of view, but when someone sees a car, it expects to hear one too. Since people were used to hear a sound from a modem, they need to hear the sound; if it is silent they might think it is nonfunctional (even with some terminal program indicating otherwise).


I listened for a dial tone - told me my phone line was working. Phone outages were common in the 80's.


Originally, you had to dial the phone by hand and listen for the carrier. When you heard it, you would place the handset into the acoustic coupler. The telcos and PTTs did not allow direct connection to the communications equipment.

Later, you could connect directly: you would pick up the handset and manually dial and listen for the carrier. When you heard it, you would toggle the ONLINE switch and hang up the phone.

When the marketing people and the pointy-haired bosses wanted to "dial in" to what the geeks were doing, they wanted to have that squeaky sound coming out of their IBM too so everyone knew they were ahead of the game and working hard. After that, it just became the way things were and always had been.

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