The Sound of Dial-Up: How Modems Got America Online
The screech, the static, the busy signal when Mom picked up the phone. A short history of the modem.
By the InterStalgia history desk · November 14, 2026
If you went online in the 1990s, you can probably still hear it. A dial tone, the beeps of the number, then a burst of screeching and static while two machines figured each other out. That noise was the sound of data being turned into sound.
Turning data into noise
The phone network was built to carry voices, not computer data. A modem, short for modulator-demodulator, gets around that by converting digital data into audible tones that can travel over an ordinary phone line, and converting the tones back on the other end. Early modems used sounds you could hear because that's all the phone system could carry.
Early setups used an acoustic coupler: you put the telephone handset into a cradle with a speaker and a microphone lined up with the handset's ends, and the computer literally whistled into the phone. AT&T's Bell 103A standard, from 1962, set the pattern for the 300-bits-per-second connections that early hobbyists used.
Hayes and the AT command
In 1981 Hayes Microcomputer Products released the Smartmodem. It ran at 300 bits per second, and its big idea wasn't speed. Instead of flipping switches on the front of the box, your software could control the modem by sending it text commands. Those commands, which start with "AT," became the standard, and almost every modem made since uses some version of the Hayes command set.
Faster, and faster
Through the late 1980s and 1990s, engineers kept squeezing more data out of the same phone lines by packing more bits into each signal. Speeds climbed to 14.4k, then 28.8k. USRobotics released a 56k design it called X2, for twice the speed of 28k modems. Rival 56k designs didn't work with each other until February 1998, when the International Telecommunication Union announced the V.90 standard that everyone could support.
That was about as fast as dial-up ever got. Phone line quality and noise slowed it down further, which is why "56k" usually meant something less.
Tying up the line
Dial-up's real cost was the phone. A dial-up connection needed the phone line all to itself, so while you were online, nobody in the house could make or take a call without a second line. When AOL switched to unlimited monthly pricing in December 1996, so many people stayed connected that subscribers spent their evenings listening to busy signals instead of the handshake.
The last connection
Broadband didn't become common until well into the 2000s. A 2008 Pew Research Center study found that only 10% of American adults were still using dial-up. Providers began switching it off. AOL, which had put more Americans online through dial-up than anyone, ended its dial-up service on September 30, 2025, after 34 years.
The handshake sound outlived the service. It still shows up in movies, memes and the memories of anyone who ever waited for a webpage to load one line at a time.