Novitiate gate – locator

How do you contact a novitiate master when you can’t find him?
For modern people, it’s easy. All you have to do is make a phone call…. but Camaldolese monks do not use cell phones. Nowadays, the monastery has a switchboard and in-house telephones (the ones with a dial!), but how was this solved before? The novitiate master used to mark on a special plate where he could be found and if he was busy.