Wasn’t it Olivetti that had smart badges that’d use IR to report to in-room receivers so you’d know where someone was and calls could be routed to the nearest phone? I remember they had a trivial do not disturb more - just place the badge face down and the receivers wouldn’t be able to find you.
I don’t remember that. But the phone number to get the Olivetti operator from my apartment out on Gugliemo Jarvis was a single digit like 6. It was after all a company town which BTW emptied out on weekends. People tended to go home.