The LEF-10 is a selective calling open voice style master station with the capacity of up to 11 total stations. The system can be designed to meet a wide variety of needs, including any combination of master and substations up to its maximum capacity. Incoming calls from a sub or door station are annunciated with a momentary electronic monotonous sound and an LED, remaining lit for approximately 2s. Communication at the calling master is press-to-talk, release-to-listen. The person at the receiving station speaks hands-free. The person at the master station can selectively call and talk with a person at any other sub or master station in the system. The privacy feature on the master and selected subs prevents eavesdropping from the master station. A call can be received, but communication back to the calling master will be heard only after the privacy button is disengaged.