If you do not have this information, please give us the dimensions of your master station and remove one of your inside stations and let us know how many wires you find.
Selective room call is a feature that enables a private conversation from the master station to an individual room without the conversation being broadcasted throughout the entire intercom system.
All call broadcast is where the intercom functions so that every speaker, unless either turned off or in monitor mode, will broadcast the conversation throughout the entire system.