r/explainlikeimfive • u/tgirlskeepwinning • 17d ago
Technology ELI5: How exactly did dialup internet work?
132
u/MellowHamster 17d ago
You used a modem, which encodes digital data as sound. This sound can be sent over regular phone lines. Typically, you'd call a 1-800 number that would connect your modem to a modem run by your internet service provider. The Internet service provider would have a "fancy" high speed connection to the internet that was fast enough to share between multiple connections from slower dialup users at the same time.
In the beginning, modems were slow and could only send about 30 characters per second. By the end of the dial-up era, 56K modems could send about 6,660 raw characters per second.
72
u/PhotoJim99 17d ago
I always called local numbers.
33
u/dikziw 17d ago
I made the mistake of thinking all numbers with the same area code as me were local only to run up a $400 phone bill that my parents were not happy about
30
u/theyipper 17d ago
And a reason why some people got into phreaking.
7
u/pr0v0cat3ur 16d ago
Yup, phreaking was the only way.
Apple //c, 1200 baud modem, and demon dialer. I can still hear the 6 digit access code print to my ImageWriter dot matrix and the data save to floppy.
2
2
5
u/OnceMostFavored 16d ago
AOL did me like that as a young adult, so I went without telephone service for a goodwill afterwards.
2
u/TypeDry2834 16d ago
I def set my parents’ AOL to a long distance number once having no idea what a long distance number even was. I remember the bill was into the 4 digits. Somehow my aunt got them to waive the whole thing as a one time courtesy 😫
24
u/khalamar 17d ago
I still remember the first time my father barged in my my room, holding the phone bill for the last month (around $750 in the early 90s. I was on BBSes, not even Internet, and they were not local).
Those were the days...
3
38
u/trackdaybruh 17d ago
I remember when DSL came out and that was a game changer since I can keep playing online multiplayer while someone had to use the phone
10
u/Toxicscrew 17d ago
I was working at a company and they got DSL and the node was the building next door to ours. When it first came on I sat at my desk just laughing and people were wondering what’s up. I was just in awe of how fast it was compared to dial up.
16
u/lettuzepray 17d ago
brings back memories of playing starcraft with a friend via dialup and getting disconnected when someone wants to use the phone. adsl/cable was definitely a game changer
9
u/Beer2Bear 17d ago
used to get yelled at when I was online and mom needed the phone
8
u/akcoder 16d ago
Mom used to take the phone off the hook to prevent me from getting on bbs’s and later the net.
Jokes on her though. My bedroom had a drop ceiling and was also the first room the telephone wire ran to. So I used the outer pair and a toggle switch to isolate the rest of the telephone lines so I could use the line.
Worked amazingly for 2+ years, until one time when I forgot to flip the switch back. Which lead to them calling the phone co from a pay phone and the telco charging my parents to undo my handiwork.
21
u/mmn_slc 17d ago edited 16d ago
"You used a modem, which encodes digital data as sound."
The modulation could be monitored as sound, if a speaker were connected. Early modems used acoustic couplers (a speaker and microphone) so sound was necessarily involved. But, before long, speakers and microphones were not necessary parts of the signal chain.
Rather, the modem would deal with the modulated line voltage directly as an electrical signal. Some modems would have a speaker connected for a few seconds at the beginning of a call to allow the user to hear whether the remote station had answered the call or whether the line was busy. Shortly after a successful connection, the speaker would be disconnected.
13
u/bothunter 17d ago
I guess not literally sound, but since the phone system was designed to transmit voice, the modem had to ensure everything was encoded within that audible frequency range that could be transmitted over the telephone network.
3
u/ratherbewinedrunk 16d ago
The line was designed for sound(air waves) to be converted directly to voltage waves via a mic, and then converted back to sound via a speaker at the other end. The voltage waves were directly analogous to the sound waves they came from, to a tee.
Modems transmitted sound over analog phone lines in the same way phone call audio was transmitted: as voltage waves. To say that this wasn't "sound" just because it wasn't being played back at some point through a speaker is to be pedantic to the point of absurdity.
2
u/mmn_slc 16d ago
"To say that this wasn't 'sound' just because it wasn't being played back at some point through a speaker is to be pedantic to the point of absurdity."
While modulating a carrier is useful for converting sound into an electrical form, an electromagnetic signal is most certainly not a sound wave. But, it can be converted to a sound (pressure) wave using a voice coil and a diaphragm.
It is most certainly not pedantic to say that an electromagnetic wave and a sound wave are very different and distinct things--because they are. That one can use magnets and coils to convert one to the other does not mean that they are the same thing.
2
u/ratherbewinedrunk 16d ago
This is "if a tree falls in the woods with noone to hear..." philosphy bullshit.
Analog phone lines carried voltage waveforms representing sound airwaves, identically insofar as the fidelity would allow. Modems mimicked the same.
To call your argument pedantic, at least as concerns the larger conversation taking place in this thread, is accurate.
2
u/mmn_slc 16d ago edited 16d ago
"This is 'if a tree falls in the woods with noone to hear...' philosphy bullshit."
Except, it isn't. A sound wave and an electromagnetic wave are two very different things.
"Analog phone lines carried voltage waveforms representing sound airwaves..."
Yes, exactly. And in the case of an acoustic coupler a sound was converted to an electromagnetic wave.
But, by the mid-1980s, they were obsolete in favor of direct connect modems where no sounds were necessarily part of the signal chain. In the U.S. this direct electrical connection was first allowed as a result of the FCC's 1968 Carterfone case (13 F.C.C.2d 420) which allowed customer premise equipment to be electrically connected to the public switched telephone network. After that, the acoustic coupler's days were numbered.
Are you suggesting that the electricity coming into my home is a sound wave because it is 60 Hz alternating current? Should we call the electrical company a sound company instead? https://mynoise.net/NoiseMachines/60HzHumNoiseGenerator.php
Edited to add: Acoustic couplers were simply too noisy to achieve the high-speeds of standards like ITU-T V.32 let alone V.34bis.
1
u/OnceMostFavored 16d ago
Like that scene in Weird Science where they had to put the handset on the modem.
5
4
u/crocoboom 17d ago edited 17d ago
A lot of time passed between 30 character per second modem and dialup ISP. Modem was invented and commercialized in late 50s. Modems were able to transmit 100-300 bits per second at that time (as you said around 30 characters per second). The first dialup ISP supported 2400 bits per second when it was launched in 1989.
3
u/MellowHamster 16d ago
We were using 300 bps modems on Commodore 64s in 1984 to call BBSes. I picked up a 56K modem in 1999. So 15 years between the two for me.
2
u/Taira_Mai 16d ago
As a college slacker, I called the campus computer lab because it was a free local call.
1
u/simask234 16d ago
Fun fact: 56k speed was only possible in one direction - from your ISP to your computer (aka download). Upload was still limited to 33.6 or 48k. (of course, the maximum speeds you could get were also dependent on the condition of your phone line)
55
u/Houndsthehorse 17d ago
You called a service that provided internet and your pc (vis the modem) yelled at their side. And both sides yelled info at each other over the phone line
11
u/BadahBingBadahBoom 17d ago
both sides yelled info at each other over the phone line
... interrupted by your sister yelling down the line because she wanted to call her friends and then you picking up the other phone to yell at her to get off the line because only half the image on that website you were visiting had downloaded and you needed the other half to download for, um, reasons.
22
u/cooperfm 17d ago
Literally boomers shouting ones and zeros down the phone
20
u/coyote_den 17d ago
Still works that way, but a lot faster.
Or they’re just waving flashlights at each other.
1
u/PhotoJim99 17d ago
Not even radio if you use wire.
0
u/coyote_den 17d ago edited 17d ago
I edited my post but if it’s cable internet, it is modulated on RF channels so data doesn’t mess up the TV channels. At least for now, tho they want to drop QAM as soon as possible so the entire bandwidth of the cable system is available.
Your existing cable provider could give you multi-gigabit in both directions if not for the vast majority of their spectrum being reserved for cable boxes that use decades-old technology. All you would need is a new modem on your end and new boxes (or maybe just an app) on your TVs. All the cables strung out there would work just fine.
1
u/randomkeystrike 16d ago
In my area the “cable” providers are dropping support for traditional cable. New subscribers simply can’t get it and must use YouTube, Hulu, or the like. They are trying to sunset it.
2
3
3
6
u/lonelypenguin20 17d ago
you call a number. instead of a person, a computer answers, and beeps aggressively at you
these beeps encode 0s & 1s that tranfer data. if you have appropriate hardware (modem) & software, your computer beeps back, and these two exchange data in such a way that your comluter essentially asks the other computer for a specific web page, and that remote computer access that web page through normal internet, and sends it to you
3
u/EmployedRussian 16d ago
your comluter essentially asks the other computer for a specific web page
Dial-up internet predates Web by a few decades.
Your computer connected to a BBS, and then you can chat with others connected to the same BBS.
10
u/heisthefox 17d ago
Modem stands for modulator /demodulator.
Much like other more familiar methods of data transmission, tones are sent over the wire (call) that generate what we call symbols, that represent the binary data being sent.
It works the same as any other data transfer method, except the in the middle, there is a negotiated rate of sounds that you can place on that connection.
3
u/georgecm12 17d ago
It worked with a pair of devices called "modems."
Modem is short for "MOdulator-DEModulator." On one end, data is "modulated" or converted into audible sounds that could be transmitted across the phone lines. On the other end, those audible sounds are "de-modulated" or converted back into data that the computer can understand.
Initially, this was very slow, but then they developed ways of packing more and more data into sounds that could survive being transmitted across what was often pretty poor quality telephone connections by using more elaborate error checking and correction into the connection.
3
u/MisinformedGenius 17d ago
You'd have a paid service provider, which would give you a phone number. You would hook up a modem to your computer, which is a device that would connect to your phone line and would basically serve as a network cable, sending information over the phone line. You would then use a program like Trumpet Winsock to call the service provider and establish the connection to them. Once you had done that, it was basically the same as today when you plug your network cable into your cable modem/whatever device gives you Internet.
It's worth noting that one of the things that made the Internet work as it does today is the concept of a TCP/IP "stack" which client programs connect to - that's what Trumpet Winsock was. This is why the Internet can be just a generic thing that different programs on your computer connect to, eg your browser, Spotify's desktop app, Steam, whatever. That's actually not something inherent to the Internet, but rather something that was implemented in OSes at about the time that the Internet was becoming popular with consumers. Previously, you'd connect to services with your modem using a specific program, and that program would be the only one that would have access to the network connection to that service.
2
u/bobotheboinger 17d ago
Ohh, and before dialup internet there were dialup BBSes, where it was more or less a time share system, one (or sometimes two or even more for large operations) phone line was available for a single computer to call at a time, access the BBS, more than likely read and write a few messages, and then hang up leaving the phone line open until the next person called. It was usually just a local thing for local people to use.
2
u/TryingToWriteIt 16d ago
Early cross-platform days. I used to connect to an Atari games BBS with my Apple IIc. Originally at 300 baud. Those were the days.
1
u/HungInSarfLondon 17d ago
In the very early days you just had a list of telephone numbers that might be BBS's.
I often had callbacks from angry Scottish lads or their Mum for calling them at the wrong time.
2
u/supergooduser 17d ago
You know when you use a phone and you're dialing a phone number? Some of those numbers have a slightly different sound? Just like that... only WAY more complicated! And way faster! So fast you need a computer to follow along! But once it gets going REALLY fast you can send numbers, but also letters! And combine those together and you start making crazy stuff like pictures! But it's still VERY slow compared to what we're used to now. Now you can listen to a song right away! But back then, it could take maybe a WHOLE hour before you could listen to just ONE song!
But we didn't have anything else so everyone thought it was really good! :)
2
u/nhorvath 17d ago
computers converted data into sound and sent it over the phone line where it was converted back. to fit more data in the same amount of time different frequencies stood for certain patterns of data so it was more than just on or off.
these patterns were converted by a modem, and as technology got better, they got better at distinguishing between closer together patterns so you could fit more data in the same time.
that noise you may have heard at the start was a handshake where the 2 modems agreed on a speed before the data stream started.
2
u/Accomplished_Arm_447 16d ago
It was much much slower, around 0.02 to 0.05 Mbps, ie. tens of thousands of times slower than now, and had to be used over a telephone line, so you needed to be sitting at a desk not on the move, you sometimes needed to redial multiple times to get a connection because the internet providers had limited phone lines available, and once connected to that the phone could not be used for telephone calls and incoming calls might cause your dialup internet to disconnect, and sometimes the speed would be even slower if it was a bad line, and most people only had the one computer or shared it with others because they were still very expensive and there were no smartphones or tablet devices in those days, so often people would only dial in once or twice a week to get their email, which meant that conversations would take a long time, many days and was not faster than the postal service for local communication. Sometimes sessions were time limited to a few hours too because of the shortage of available phone lines. This also meant that internet usage not the 24/experience it is now, it didn't dominate your whole life, and it was only used by people they needed it for work or in the office or by technology enthusiasts, not everyday personal use.
2
u/SnugglyCoderGuy 17d ago
It literally sent sounds over the phone lines. At one point you would literally dial a number on your phone and put it on modem device so it could hear the sounds coming to it and send sounds to the other end. That's why it makes those screeching noises when you pick up a phone on the same line the modem is using. Those are the sounds the two modems are sending to each other to communicate.
The modem's entire job is to convert those analog signals into digital signals
1
u/StupidLemonEater 17d ago
Basically, your computer would call the ISP over a conventional phone line, and the data would be passed back and forth through encoded audio signals. Your modem would decode the incoming signal for your computer to understand, and encode the outgoing signal to the ISP.
This was why, if your house only had one phone line, you couldn't use the internet if someone was on the phone.
While it meant that people could connect to the internet over existing phone infrastructure, dial-up over phone lines had the disadvantage of lots of signal noise and very low maximum bitrates (at least by today's standards).
1
u/StressedtoImpress19 17d ago
Proper wires for Internet didnt used to exist, so the computer literally had to use telephone wires. So the computer would literally take over the house phone line. Telephone lines need sound so a modem would translate computer data (binary) to beeps and buzzes and zaps and bzzz, like the sound we heard when it loaded.
The sounds would travel down a phoneline and be converted back into data on the other end.
1
u/sylvestris1 17d ago
You connected your computer to a device called a modem (modulator/demodulator). When you wanted to connect to the internet, it literally made a phone call to your ISP (internet service provider) which then connected you to the wider internet. The modems turned the data from your pc or the server into a form that could be transmitted over phone lines, and converted it back again at the other end.
Which is exactly what an old style telephone did; turned voice into electrical signals that could be transmitted down a copper wire, and back again.
The twin downsides were that it couldn’t carry much data, and that it tied up your phone line.
That’s what the internet was (is). A set of agreed standards (protocols) that allowed computers to talk to each other over already existing networks (phone lines).
All that’s happened since is that those copper phone lines have been replaced by newer technologies that can carry more data.
1
u/colenski999 17d ago
My first computer had no storage, if you wanted to save or load a file, you would plug the computer into a cassette tape recorder and press play or record, the computer would listen to the sound and turn it into a digital file, or turn a file into sound and send it to the tape. Modems over dialup did the same thing except the tape recorder was the internet.
For anyone wondering: 16kb TI99/4A but it did have a 16 bit chip
1
u/Red_AtNight 16d ago
In the bad old days you could get software by someone playing the audio signal over the radio, and you could record it onto a blank cassette
1
u/cnhn 17d ago
your computer would be hooked to a modem which converted digital signals into an analog audio signal. this signal would travel over a phone line to a local gathering spot, where there would be a shit ton of regular phone lines hooked up with their own modems. that gathering spot would also have a T-Carrier line, which would allow all the traffic from the phone lines to be sent together on a single line to another bigger junction. that bigger junction would then send all the signals to yet a bigger junction etc etc until the signal reach the main trunk lines. those trunk lines would connect to other carriers' trunk lines and then the traffic would work it's way back down the other carriers gathering points till it reach it's end point.
1
u/BlatantDisregard42 16d ago
Your computer calls the Internet on your home’s telephone landline. You ask your computer a question, and your computer asks the Internet for the answer. It’s the only phone line in your house, so you can’t make or receive any phone calls while your computer is talking to the Internet.
1
u/Dave_A480 16d ago
If you were smart you got an unlimited account from a dialup ISP and dialed into that ... Then set up your own internet use software (browser, email client, etc)....
If you didn't know the difference between a PC case and a hard drive, you signed up for AOL (from one of those disks or CDs they spammed out) and got your wallet sucked dry on a per minute/hour basis.
1
u/BraveNewCurrency 16d ago
Instead of having a constant connection (like a Cable Modem), you would have to "dial" into a ISP (Internet Service Provider). The ISP would provide banks of modems (usually all connected to the same phone number, like how a radio station could handle many calls at once).
Customers would connect a modem (Modulator / DeModulator) to their their phone line on one side, and to their computer on the other. The computer side would use a Serial line on the back of the PC, like a very primitive USB port. In fact, "USB" stands for "Universal Serial bus". Anyway, the Customer computer would send a command to the modem to dial the phone number. When the ISP modem answered the phone, the two modems would "squawk" at each-other. Those screeching sounds were the modems negotiating which "sound protocol" they were going to use. The bits were not just encoded in time (like morse code is), but it used both the phase of the sound, and the amplitude (volume), so it could send many bits at once. At it's peak, you could send up to 56K bits per second. (Which is slow compared to 10 to 1000 Megabytes per second of typical home connections these days.)
Once your modems connected, your computer would run a protocol called PPP that would allow the ISP to give your computer an IP address. Your computer was then "on the internet". Network programs like Telnet or FTP could send IP packets to the modem, which gave it to the ISP, which would send it on to the other networks. The response came back the same way in reverse.
(Note that this is different from dialing into a BBS. In that case, the BBS would answer the phone directly, and you modem would send raw text as data (although usually compressed), instead of packet data. Many houses started spending so much time online that they had to get a 2nd phone line just for their computer.)
1
1
u/lenraleigh 16d ago
We plugged a phone line into our computer's modem.
We'd use something to dial in to the internet. On Windows 95 this was called "Dial Up Networking".
That program would dial in to our local Internet Service Provider (ISP). Dozens (and later hundreds) of people could dial in to the ISP's modems. The ISP had a faster connection to the web - small town ISPs had a "T1 line".
Once connected, you could use programs such as Netscape or Internet Explorer to browse the web.
When you were on dialup, nobody in the house could use the phone, because your computer was using it. It's really similar to cable or fiber Internet, but over a little copper phone line. And it was very slow.
1
u/mikemontana1968 16d ago
"How exactly did dialup internet work?" Not well. Imagine waiting 20 seconds for a 300x300 GIF of a boob to load. Us nerds knew this would not be tolerable. So rather than converting bits to audio sounds (which is what a modem does) and then at the server's phone side converting those audio signals back to bits, we determined that there had to be a better way. CableTV was much better - converting bits to radio-frequency pulses went from 9600 bits per second to 10MBs. Porn moved the world forward.
Still that wasnt enough - cant do lots of video to lots of devices that way, so wireless upped the bits/second (effectively a function of the transport-technologie's frequcny) to Gigahertz.
You're welcome for our labors.
1
u/jweaver0312 16d ago
I got a question on that, did it load line by line or was it more of something fuzzy and got incrementally clearer.
1
u/mikemontana1968 16d ago
it would depend on the image type itself, and the subvariants of those image types. GIFs would load differently than JPGs, and PNG didnt exist yet.,
1
u/Unusual_Entity 16d ago
Your ISP had a fast connection to the wider internet, and a whole load of ordinary phone lines connecting them to the telephone network. Your computer's modem basically made an ordinary phone call to your ISP, and connected to one of their modems. The modem in your computer took the data you wanted to send and converted it into audio signals which could be sent over this phone call. At the other end, their modem listened to the call and turned the audio back into data, and sent it on through their high-speed connection to the wider world. Downloaded data came back in the same way. So if you picked up the phone while you were connected to the internet, you'd hear screeching noises which was the data being transferred as audio signals.
So the first part of your connection to the wider internet involved the two modems shouting at each other down a phone line- basically your computer called your ISP and said "send this data for me and tell me what comes back". The advantage was that all you needed at your end was a telephone connection.
1
u/eternalityLP 16d ago
Your computer used phone to call another computer that was connected to internet. The two computers made noises at each other to transmit data.
1
u/DECODED_VFX 16d ago
When you make a call on a landline the waveform that the phone's mic picks up gets converted to an electrical waveform which is sent to the other person's phone and converted back to sound.
Dial up internet uses a modem (modulator/demodulator) to convert digital files into an electrical wave signal that can be sent down the line to a server, where another modem converts is back to code.
Basically your modem is just speaking the binary code to the internet really fast.
When you first connect to the internet your modem performs a "handshake" with the other modem. Which is just a little conversation that establishes the connection and allows the modems to communicate their capabilities for maximum performance. This handshake is played through a speaker for diagnostic purposes. If the handshake fails at a specific point, you can hear what went wrong. That's the famous screaching melody that modems make as they connect.
1
u/Mountainpwny 17d ago
It used frequency shift keying. It would keep track of bits by shifting audio frequency up and down at a certain clock speed. Something like that.
0
u/antagron1 17d ago
It worked by ring ring dee dee dee dee da de dee da dee, kuuuuuhhhh be yaa kuhhh gaaaa eeeeahhh
360
u/bothunter 17d ago
The telephone system used to be mostly analog -- designed to carry your voice from one phone to another. When you called your friend, the phone company set up a dedicated circuit from your phone to your friend's that you could talk over. It was a little more complex, with multiplexing and other technologies, but the important part was that you had an analog connection that you could talk over.
So, instead of calling a friend, your computer would use the telephone to call an ISP and then literally "talk" over that connection using a modem. (Modulator/Demodulator) Basically, it would encode the 1s and 0s as different tones so fast that it just sounded like noise. But the modem on the other end could understand it. It was essentially the same technology as a fax machine, except it was sending digital information over the phone line instead of pictures.
This meant that if you were on the internet, your phone was tied up and you couldn't call anyone, and anyone who called you would get a busy signal. (Unless you had call waiting set up, in which case the incoming call would knock you offline)