The Aiphone LEF-3 Open Voice selective-call master intercom works with any combination of up to three Aiphone LAF and LEF Series master intercoms or LA, LE, and LS Series door and sub-master intercoms (sold separately) to enable audio communication with a visitor at a door and with other rooms within the building. Three buttons with LED indicators allow the master intercom to direct a call and communicate with the desired door or sub-master intercom. Calls received from a sub-master intercom are indicated by a momentary chime and the corresponding LED indicator above the selectable buttons illuminating for 20 seconds. Depressing the push-to-talk button on the master intercom allows the user to talk to the specified door or sub-master intercom user, and releasing the button immediately transmits sound from the door or sub-master intercom to the master intercom. The privacy button prevents other intercom users in the system from overhearing a conversation with another intercom.

At any time, the master user can listen to audio transmissions from a specified door or sub-master intercom. The chime and audio volume is adjustable, and switching the power button to off silences the master intercom's chime alerts. The housing is white plastic and mounts to a desktop or wall using the included mounting hardware. The system is hardwired to be powered by a 12V power supply (sold separately).

*H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distanc