Could it be an auto-answer from a Telex machine?
https://youtu.be/lCZmVXGyVQQ?t=15
I have no idea what they sound like on a telephone line though.
8 karma · joined December 2, 2015
https://youtu.be/lCZmVXGyVQQ?t=15
I have no idea what they sound like on a telephone line though.