A system can be designed for the two way speech from the entrance door(s) to handsets inside the building. The handset includes a button which releases the door.
Audio systems can have a separate CCTV system incorporated to provide images to a separate monitor for a more flexible system.
 |
 |
 |
The system as above but includes mono (black & white) or colour images transmitted from the door to the handset being answered. This provides a more secure premises as the person being admitted can be visually identified. The camera is normally fixed within the control unit.
Controller:
Single to multiple button access. Provides speech and if applicable video images to the handset(s).
Handset:
Similar to a telephone with a button to release the door lock and allow access. Video units include a small LCD display.
(All images shown are Bell Systems.)