Hydrogen cyanide will turn into “cookie dough” in 1-5 years. Which is way shorter than “forever”.
The way you said it in your first comment made it seem longer lasting than radioactive waste. Which it isn’t according to the linked PDF. That is the only point I was trying to make.
Don’t fax machines directly initiate the handshake?
I remember being screamed at by angry modem noises in ancient times when calling a fax number.