Nostalgic Journey: Hayes-Compatible Modems and AT Commands

Dimitris Moutsatsos
2 min readApr 18, 2023

This post is dedicated to those who remember the days of using Hayes-compatible modems to connect to the internet. Back then, we relied on serial communication applications like HyperTerminal or Minicom to configure our modems. The AT+MS command was used to set the modulation scheme and connection speed, while the ATDT or ATDP command dialed our ISPs.

My favorite modem was US Robotics 56K

U.S. Robotics 56K Message Modem

AT Commands:

Here’s a nostalgic look back at some of the AT commands we used:

  1. AT — Check if the modem is connected and responsive. Returns “OK” if connected.
  2. ATE0 — Disable command echo. The modem won’t echo commands back to the terminal.
  3. ATE1 — Enable command echo. The modem will echo commands back to the terminal.
  4. ATI — Display modem information, such as model and firmware version.
  5. ATZ — Reset the modem to its factory settings.
  6. AT&W — Save the current configuration to the modem’s non-volatile memory.
  7. AT&F — Restore factory settings.
  8. AT+MS=? — Display a list of supported modulation schemes and connection speeds.
  9. AT+MS= — Set the modulation scheme and connection speed.
  10. ATDT — Dial a phone number in tone mode. Example: ATDT5551234
  11. ATDP — Dial a phone number in pulse mode. Example: ATDP5551234
  12. ATH — Hang up the call.
  13. ATS0= — Set the number of rings before the modem answers an incoming call. Example: ATS0=1 (answer after one ring)
  14. AT+VCID= — Enable or disable Caller ID detection. Example: AT+VCID=1 (enable Caller ID)
  15. AT+VLS= — Set the modem’s speakerphone mode. Example: AT+VLS=1 (enable speakerphone)
  16. AT+VSP= — Set the modem’s speaker volume. Example: AT+VSP=2 (medium volume)
  17. AT+VRA= — Set the ringback timeout. Example: AT+VRA=20 (wait 20 seconds for ringback)
  18. AT+VNH= — Set the microphone gain. Example: AT+VNH=1 (low gain)
  19. AT+VDR= — Set the DTMF tone duration. Example: AT+VDR=100 (100 ms tone duration)

Funny material:

US Robotics Modem Commercial

Modem sound when connecting

Those were the days, weren’t they? If you’ve ever used these commands, you’re part of a unique era of internet history.

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Dimitris Moutsatsos

developer and weirdo / current: Tychetech / MAD TV / WARR