| 摘要 |
<p>The system includes a door-bell unit (10) for positioning on or adjacent a door of a secure location, such as a building. The unit has a bell push (14), a microphone (16) and a speaker (18). Programmable control means include a memory (20) for storing the dial-up number(s) of at least one remote telephone (22); dialling means (24) for dialling a selected dial-up number from the memory (20), in response to the bell push (14) being actuated by a caller, thereby to establish two-way voice communication between the door-bell unit (10) and a selected remote telephone (22) associated with the dialled dial-up number; and means (28) for preventing the ring tones of the selected remote telephone (22) from being broadcast through the door-bell unit speaker (18).</p> |
