Wow. Now _that's_ something I've not even thought about in decades. Those were irritating when trying to BBS in somewhere at 2AM and you didn't want to wake the whole house. (Not many of us had dedicated data lines then.)

I remember one of my local BBSes had a busted call back that would occasionally call multiple times or after a random (and often very long) delay.

So much of that era is just forgotten now (and that's not necessarily a bad thing...).