The high performance AiPhone DB-1SD HANDS-FREE SUB MASTER STATION is a hands-free sub master station that has a tone volume control with mute indicator, receive volume control, All Call button, Talk button, and Off button can connect 4 wires to the DB-1MD master station.

• Used with the DA series door stations
• Up to 5 stations per door call button
• All calls between stations in the same residence
• Internal communication can be hands-free (VOX) or push-to-talk (PTT)
• Door release is powered by the door station without the need of an additional transformer
• Call tone volume control with mute indicator
• Receive volume control
• Optional Call Extension Sounder