| 摘要 |
(57) The front door telephone system is intended to be used especially in apartment buildings. It comprises mainly a keyboard (2) located by the entrance of the building, a central unit (5) and a combination of remote units (8) connected to the central unit (5) and located in the apartments of the buildings. The front door telephone system specifically facilitates opening of the front door (1) from the remote unit (8). Fig. 1
|
