>>5718675 (pb) ← previous notable
One more note - oldfag is also correct - there were plenty of systems with modems connected with zero security. I've seen them broken into. That's what "war dialers" were all about. I've done it, it works. Amazing what you could find wide open at that time.
Another fun note: The phone number 415-666-6666 went to some desk at the mathematics department of UC Berkeley before or around 1980. Oh…the things that are remembered…