Aiphone audio only security intercom with door release built into the door station. 

Power Source	
15V AC - Use AC transformer PT-1211C, 120V
Communication	
Hands-free (VOX) or Push-to-Talk (PTT)
Door Release	
Contact rating: 9.5 ~ 20V AC, 70Ω resistance, or use EL-12S
Wiring	
Door to master: 2-cond, master to sub masters 4-cond
Distance	
Door to master: 360’(22AWG) 1020’(18AWG)
Master to farthest sub: 330'
Wire Type	
Door to Master: Aiphone #822202 or 871802
Master to Subs: Aiphone #812205 or 871804

Please Note : For every 2 room stations a T1615 power supply is required. A T1615 is included in the Aiphone DB Series Intercom Kit.