If you're an old codger like me you probably at some point used a modem to connect to bulletin boards, dial=up services like Compuserve and AOL - and yes, even the Internet.
This repo contains an example sound from those days.
The sound files are actually edited versions of an original file (generously released under the Creative Commons Licence) which can be found here:
https://freesound.org/people/schluppipuppie/sounds/8057/
I edited the original sound files to be shorter and more succinct overall and to scramble some of the data.
The sound files were created as a result of a conversation on Twitch with Jeff Fritz about his Epic Build Music VS Extension where I jokingly suggested the default build sound should be... a modem carrier and DTMF tones. So here it is. :)
The sound is available in WAV, MP3 and Flac, all in stereo.
Issued under The Creative Commons v3 Attributions licence: https://creativecommons.org/licenses/by/3.0/
Go on, time travel every time you build!
Ian Barker