From 300 baud to multiple gigabits per second, it’s time to celebrate the history of the modem. It occurs to me that we will soon be entering a period where no one will remember the ear-shredding screech of a dial-up modem connecting their computers to the internet—all the while hoping no one picks up the phone and wrecks it.

The humble modem is, at least as a device sitting on your desk alongside your computer, largely consigned to history—and more than a few recycling centers. And though their speeds and connectivity have long since been surpassed, it’s still an amazing piece of engineering, and you might be surprised to know that, 60 years later, a lot of that unlying technology is still in place today.

What is a modem, exactly?

Back in the day, how would you connect two computers together to exchange data? Why, using a serial cable, of course (if you haven’t seen our look at The Surprising History of the Serial Cable, you should)! But what if the other computer was too far away to connect with a physical wire? In another building, another city, or even another country? Enter the modem.

Like the serial cable, the modem was designed to solve a pretty basic need: to connect one computer over a long distance to another. To do it, that connection had to use some kind of network. Pre-Internet—yes that’s a thing—that meant making use of networks that had that kind of widespread connection across the world–mainly the analog phone system.

So how would that work? Take this scenario: Computer A, located in Toronto, wants to send data to Computer B in Orlando. Since computers store and transmit data digitally, we need some kind of device in the mix that can convert that into an analog signal (or modulate the data) so that it can be sent over the phone system. Same issue on the other end: The data will need to be converted back into a digital format (or demodulated) so Computer B can receive and process it. It would be cumbersome to have separate devices for both the modulation and demodulation processes, so they come together in a single box – The MODulator DEModulator, or MODEM for short.

The following clip from the 1983 TVOntario program Bits and Bytes is precisely where I first learned how modems functioned when I was young.

1950s: It’s big, but it works (~100 baud, 0.1kb/sec)

The first mass-produced dial-up modems were produced beginning in 1958 for the SAGE (Semi-Automatic Ground Environment) air-defense system. SAGE computers received information from a net of radars arrayed to detect and track aircraft. SAGE was capable of further processing this tracking data to form awareness of the complete air situation and guide weapons to enemy aircraft.

A 1950 SAGE air defense system radar unit
If you look just under the railing, to the left of the radar screen, you can see the ashtray and cigarette lighter. Because 1950’s.

Until 1966, the SAGE Digital Radar Relay system used dial-up modems to connect terminals at radar sites, command and control centers, and air bases to SAGE centers across North America.

Fun Fact!
After being decommissioned, some of the SAGE computers made their way into Hollywood, becoming props in two of my favorite movies: Colossus and Dr. Strangelove.


Still from the Movie Colussus: The Forbidden Project
Branding is important for an evil supercomputer made of old SAGE parts

By 1959, a commercial version of the SAGE modem was released as the Bell 101 by AT&T. Called a “dataset” rather than a modem, the Bell 101 could send or receive data at 110 bits (0.11kb) per second. It was also only half-duplex–meaning it could either send or receive data, but not both at the same time. Not only was the Bell 101 the first commercial modem, but it was also the first commercial device to use ASCII to encode text.

The Bell 101 & 103A looked virtually identical
The Bell 101 & 103A looked virtually identical
Fun Fact!
During WWII, the Allied forces and Bell Labs designed a method of voice encryption, SIGSALY, that converted speech to digital data using a vocoder and buried in random noise. It’s arguably considered one of the first real modems.


1960s: The new standard (300 baud, 0.3kb/sec)

The successor to the Bell 101 was the Bell 103A. It was a significant upgrade—at 300 bits per second—it was nearly triple the speed. And it was also full-duplex (it could send and receive at the same time). The Bell 103A set the standard for 300-baud communication, and other vendors made modems compatible with the Bell 103A standard.

Image of the 103A instruction manual

Editor’s note: for those, like me, that didn’t know, one baud is roughly equal to one bit!

1970s: Success breeds competition (1200 baud, 1.2kb/sec)

Throughout the seventies, vendors other than AT&T made modems compatible with the Bell 103A standard. But what was really interesting was the birth of the modem hobbyist. Hobbyist modems for home users began to hit the market throughout the decade. The majority of these devices were 300 baud, and compatible with the Bell 103A standard. One of the more interesting examples of these devices was the Pennywhistle modem which was sold in kit form.

The Pennywhistle Modem
The Pennywhistle Modem. Look at that lovely serial port too!

The Novation CAT was another popular modem compatible with the Bell 103A standard. It was badge-engineered and sold under many names – including the Atari 830 modem in the title image of this article.

The Novation CAT

In 1976, AT&T (basically the Apple of its time) decided to leave the competition in its dust. The Bell 212A hit the market with a bang, quadrupling speeds to 1200 baud. It was also compatible and able to communicate with the older Bell 103A standard at a lower 300 baud.

The Bell 212A

An important innovation of the 212A was that it introduced the ability to auto-answer a phone. The majority of modems during this time were acoustic couplers – the user required a regular phone to dial the remote computer, then the handset was pushed into the modem (which had a speaker and a microphone). The 212A could connect and disconnect without the user needing to dial, wait, insert the headset, then physically disconnect and hang up.

Fun Fact!
One of the reasons for this handset cradle design was that legally only AT&T was allowed to create equipment that connected directly to the phone lines. Acoustic couplers circumvented that law.


1980s: The wild years (9600 baud, 9.6kb/sec)

The 1980s were an eventful decade for the modem. In 1981, Hayes released the Smartmodem. The Smartmodem seemed modest at the outset: just 300 baud and adhered to the old Bell 103A standard. But what made it special was that it introduced a command set that could be used by the computer to control the modem. Prior to the introduction of the Hayes command set, dialing and connecting to a remote computer was a highly manual process. Now, there were commands to dial a number, hang up, answer a call, or change settings for a particular call.

The majority of modems manufactured after the Smartmodem either included the Hayes command set or a variant of it. Direct connect modems, which no longer required the use of an eternal phone, quickly became the norm in the 1980s.

the Hayes
This is starting to look like something most of us will remember!

Modems hit pop culture

The 1983 movie WarGames introduced many people to modems. In one pivotal scene, Matthew Broderick’s character David uses his modem to systematically dial every single number in a specific area code hoping to find the number for a video game company so he can play the latest games. This is an actual technique that was used by hackers in the 1980s and 1990s to find phone numbers with connected modems. This process came to be known as Wardialing after the movie, and a variant of the term is even used today – Wardriving (a process of looking for open WiFi networks while driving in a vehicle).

A still image of Matthew Broderick in WarGames
The only winning move is not to play. Source: MGM

In 1984 speed standards doubled again, hitting 2400 baud. This increase really helped to boost the popularity of modems, as the speed was now sufficient to make file transfers feasible (I have memories of waiting more than one hour to download a single file at 300 baud).

This time also saw the great birth and proliferation of Bulletin Board Systems (BBS). BBSs allowed users to post messages in public forums, exchange private messages, chat, play online games, and upload or download files – very similar to the world wide web of today.

Bulletin Board Systems screenshot
Fun Fact!
A few other notable things that happened in the ’80s, besides hair metal, are worth noting:


  • A standard for 9600 bits per second was ratified, but 9600 baud modems were prohibitively expensive and never saw widespread adoption.
  • The 1980s also saw the widespread adoption of fax machines that used the same modem technology. This begs the question, “Is the popular meme about a Samurai being able to fax Abe Lincoln true?”
text message joke

1990s: Pedal to the metal (56,000 baud, 56kb/sec)

The 1990s saw a rapid explosion in speeds. 14.4 kilobits per second modems arrived in 1991, quickly replacing the poorly selling 9600 baud modems that came before them at a much cheaper price. The USRobotics Sportster 14.4k Fax Modem was a very popular example of these 14.4 modems.

USRobtics Sportster 14.4k fax modem
I deeply regret parting with my Sportster in the 90s. So glad they included a speaker so I could hear it scream. This modem was so ubiquitous that 30 years on you can still pick up The Sportster on Ebay and other auction sites for as little as $21.

As the 90s progressed, the maximum modem speeds ramped quickly. 1993 saw 19.2k, followed by 28.8k in 1994, and 33.6k in 1996.

By the end of the 1990s, we reached accelerated adoption of the internet at home. As 56k modems—the maximum possible speed on an analog phone line—hit the market, speeds are now enabling useful and entertaining purposes (remember LimeWire?) for non-professional purposes. The coinciding rise of ISPs at prices many families can afford made the latter half of the decade the true rise of the Internet as part of modern culture.

2000s: Gone, but not forgotten

With maximum capacity reached for analog phone lines by the end of the 90s, our story ends there, right? Not yet! Never underestimate the power of profit. But there was a challenge that needed to be solved. With the combination of the cap for analog phone lines and the growing popularity of the world wide web, ISPs need to turn to other mediums to deliver the Internet at even higher speeds.

The introduction of ADSL modems allowed for greater speeds while still using existing phone lines by circumventing the phone exchange altogether. Instead, traffic is received by a digital subscriber line access multiplexer at the phone company’s central office.

Cable modems were next, leveraging existing television (coaxial) lines to carry data at much higher speeds than both dial-up and (at the time) ADSL modems were capable of. Early cable modems were simple–no extra services to allow sharing of the internet connection, so only one device could be connected at a time. This created a market for consumer routers to split up connections within the home. Eventually, ISPs began including routing hardware in their cable modems.

When is a modem no longer a modem?
Though the copper write remains the same, today’s television lines have been upgraded from analog to digital, so technically most modern cable modems are modems in name only—in the sense that they are no longer modulating a digital signal into an analog or demodulating an analog signal to digital.


Powerline adapters for using the power lines of a building for networking also contain a form of a modem. They convert the digital ethernet signals into analog signal that is sent over the building’s power lines. While not widespread they are an easily available form of a modern modem.

2020 and beyond: Everything good is on the radio

There is, however, one market today where modems live on… and even thrive. Any device using radio waves to communicate wirelessly technically has a modem. This includes technologies such as WiFi, Bluetooth, mobile phones, and even GPS. Every single cell phone contains a modem.

While not nearly as sexy as the handset of a rotary phone plugged into an acoustic coupler, it can be argued that there are actually more modems in the world today than during the peak of the dialup modem in the 1990s. A fitting next chapter for the humble modem the size of a conference room, just barely able to send one character of text in a modern email, just a few decades ago.

Neo holding a phone
There is no spoon. Just an access point.

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