Skip to content
Home » Retro Computing » Hayes compatible modem: What it means

Hayes compatible modem: What it means

A lot of software advertises itself as working with a Hayes or Hayes compatible modem. What does that mean? And what’s Hayes? It’s a de facto standard named after a defunct maker of modems. Let’s talk about why Hayes was important. It was so important, you can even still buy a USB Hayes compatible modem for legacy applications today.

Hayes introduced a command set that started with the letters AT, for ATtention. Other makers adopted this command set and cloned the Hayes modem to various degrees, leading to the terminology of a Hayes compatible modem.

What happened to Hayes modems?

Hayes compatible modem

This Hayes Smartmodem 1200 was as good as it got in 1982. But it spawned an army of imitators, and by the late 1980s, Hayes lost its spot as the market leader to US Robotics.

Hayes was a leading brand of modems in the 1980s and 1990s. Dennis Hayes, its founder, worked at various companies that designed and sold modems to commercial enterprises in the 1970s. Hayes was interested in early home computers, and he realized none of the large companies of the time were going to have any interest in selling inexpensive modems for home use. So he and a friend, Dale Heatherington, designed one. They assembled modems for sale in Hayes’ kitchen, which sounds like a good ’70s startup.

Connecting non-Bell hardware to phone lines was illegal, but Hayes and Heatherington had a workaround. And then a series of very understandable lawsuits changed the law within a couple of years. That opened the door for Hayes, who then only needed FCC approval for the product to be legal. The change in the law set the stage for a booming telecommunications industry that still exists today.

Early success

By 1978, Hayes and Heatherington quit their jobs to work at the fledgling D.C. Hayes Associates full-time, designing and building modems.

In 1981, Hayes introduced the Hayes Smartmodem, which implemented the first version of the ubiquitous Hayes command set. At $299 it wasn’t cheap, but nothing else was cheap then either. It caught on and soon Hayes was selling 140,000 modems a year. In 1982, Hayes followed up with the much faster Smartmodem 1200, which was four times as fast, and priced at $699. They were expensive but provided good value, at least for a time.

The famous Hayes Smartmodems from its heyday featured a sleek aluminum and black industrial design, and the length and width was about the same as a Bell/Western Electric 500-series telephone, so you could set it under a phone, daisy chain the phone to the modem, and still use that wall jack for voice calls when you wanted. The raised area in the middle helped hold the phone in place.


Hayes compatible modem

This Hayes-compatible modem made by Avatex shows how many companies undercut Hayes. It’s sized and shaped much like a Hayes, but made of plastic. And by using cheaper parts inside, it could sell for much less than a real Hayes, but it was almost as good.

Competition quickly picked up. Hayes used quality components, so it wasn’t hard to clone the Hayes command set and even the industrial design, and build something similar using cheaper parts. In spite of the competition, Hayes maintained 50% market share due to its high quality.

But the problem for Hayes was that after releasing a modem that ran at 2400 bits per second in 1985, it was slow to release anything faster. US Robotics answered this market need by releasing a 9600 bps modem, which left Hayes on its heels. When it finally released one in 1987 it lacked error correction, which made the USR modem look like a higher quality product. In 1988 an international standard for 9600 bps emerged, so Hayes abandoned its unsuccessful design and replaced it with the industry standard. But by then, Hayes had to share its spot at the top of the mountain with USR. The situation was very much like the situation with IBM and Compaq with 386 computers.


The growing market led to commoditization, allowing larger numbers of manufacturers to produce compatible modems using off-the-shelf chipsets from companies like Rockwell and AT&T. This squeezed Hayes from both sides. US Robotics was the best, and Hayes was the second-best. But companies like Zoom Technologies and Supra Corporation offered modems that were almost as good as Hayes, and much cheaper. If you wanted to upgrade the modem that came in your computer and couldn’t afford US Robotics, you didn’t gain much by getting a Hayes over a Zoom or Supra. So most people just bought a Zoom or Supra.

The last dialup modem I used regularly was a Hayes. But ironically, it had a Rockwell chipset in it. Virtually nothing distinguished it from lesser brands at that point.


But the biggest problem for Hayes was the future. Hayes saw way back in 1985 that the limits of copper wire would be the end of dialup modems. But it bet on ISDN becoming the standard to replace dialup. ISDN had some success in Europe and Japan, but in the United States, it never went anywhere. Instead, consumers opted for ADSL or cable modems. Hayes invested a ruinous amount of money in a product that had no commercial viability.

Hayes went bankrupt in 1994, merged with rackmount modem maker Access Beyond in 1997, and was bankrupt again by 1999. Zoom Technologies bought the Hayes name in 1999, and rebranded some of its products under the Hayes name.

What Hayes compatible meant

Hayes modems had two operating modes, data mode and command mode. In data mode, the modem just sent data over its line uninterrupted. But the character sequence +++ changed the modem into command mode, where you could enter commands to change the modem’s configuration, dial a number, or hang up the phone.

In its most basic sense, any modem that recognized +++ and the basic AT commands to hang up or dial the phone could claim Hayes compatibility. Software that expected a genuine Hayes modem might not work optimally, but it would probably work.

A fully Hayes compatible modem stored its configuration the same way as a Hayes and recognized the full command set, including the more obscure commands. This meant software that expected a Hayes modem would work just as well with a compatible modem.

In the late 1980s, as Hayes fell behind the industry, US Robotics had to extend the command set. This meant most modems were no longer fully compatible with each other. But by then, but personal computers were much more powerful and could deal with the differences by using device drivers. Terminal software would use drivers, much like word processors did with printers. And eventually, Microsoft Windows dealt with the issue at the operating system level.

Today, the modern ITU-T V.253 command set is an extension of the old Hayes command set. Wifi modems use it so early computers can get on the Internet to connect to BBSs instead of having to rely on copper telephone lines, which are increasingly rare today. This lets old terminal software work with a new modem without rewriting them, which would be impractical in many cases. And modern USB modems typically use it for backward compatibility, to support legacy business applications.

Hayes compatible USB modem: How to find one

Hayes compatible USB modem

You can still buy a Hayes compatible USB modem, like this USRobotics 5637, today.

Old-school Hayes modems connected to an RS-232 serial port. That standard has gone by the wayside, supplanted by USB. But you don’t have to use a USB-to-RS-232 adapter and an ancient modem. Modern replacements are still available.

For whatever reason, modem makers are hesitant to mention a competitor by name, even a defunct one. So to find a Hayes compatible USB modem, look for a USB modem that uses the ITU-T V.253 command set. The USRobotics USR5637 is a good choice. They sell for $60-$70 new, but used ones sell for as little as $15.

USRobotics supplanted Hayes as the industry leader in the 1990s, so if you need a Hayes compatible USB modem to replace a legacy Hayes modem, something from them is a good choice. The price difference between USRobotics and an off brand will be negligible.

Collectible Hayes modems

I admit they’re no longer especially useful. But Hayes modems make interesting display pieces today due to their industrial design and former position as a market leader in an industry that doesn’t really exist anymore. Hayes modems turn up on Ebay fairly frequently, and their prices aren’t too high, at least compared to the computers they were compatible with. You should be able to pick up a common Hayes modem that ran at 1200, 2400, or 9600 bps for under $30. For display with a 386 or newer PC, a USRobotics modem, especially a USRobotics Courier, would be a nice choice. A 56K USR Courier looks the part and is cheap. A truly vintage Courier running at 28.8 or less would be more appropriate, but more expensive.

There’s little use for a 1980s dialup modem anymore. But when I set up a vintage computer and keep it set up for a while, I like to display a period-correct modem with it if I have one. Modems were something that more people dreamed about and talked about than actually owned for much of the 1980s. But it’s a subtle touch that makes almost any vintage computer look like a dream machine of its time, and it doesn’t take much space.

It’s even possible to convert a Hayes 1200 or 2400 bps modem into a wifi modem to make it usable again. Or at least make the case look like it’s doing something again.

If you found this post informative or helpful, please share it!
%d bloggers like this: