"In Ye Olden Dayes I used to keep a rape alarm next to the telephone for busting the eardums of scammers. Wish there was an Internet equivalent."
get an old modem, and hook up a microcontroller with a button that puts it into 'answer' mode. "that tone" is ear splitting.
I was getting harassment calls at one time, started doing that consistently (put modem into answer mode) from the command line on a computer. Calls stopped.
Biting the hand that feeds IT
