That's actually a bit more common than people know; a lot of infrastructure has access via modem over the phone network. While that's realistically not been a valid application for web browsing for a long time now, it's certainly a valid way to get a command line interface to equipment without exposing it an unending stream of free security audits.

That isn't, of course, to say that there shouldn't be precautions regardless. But it's not the internet, and it lets you transmit information at a distance.