Talk-backs and their use/protocol

when we mention talk backs it refers to the intercom that a large majority of the crew use to comunicate with each other, but especially the director. The sound operator, vision mixer and DVD operator can all hear the intercom through a speaker, but the people who are in the studio hear the intercom through headphones, which are also called 'Cans'. The only people who wear cans in the studio is the camera operators and the floor manager. The cans should never be used for general conversation as they are all linked up together everybody can hear what conversations are going on over the talkback, and if the director has something urgent he needs to say to someone nobody will be able to hear him. when communicating with the director you have to do it through the floor manager, and you do it by say "cam 1 to floor manager" and the floor manager will say "cam 1 go ahead" before you start talking. This is the same if your the floor manager and talking to the director