| 摘要 |
An intercom system for use with a plurality of telephones on a single extension includes a single master station and a plurality of slave stations. The master station is connected so as to interrupt the telephone line pair to and from a central exchange. Each slave station is preferably associated with a handset that is on the extension. When the extension is not being used for intercom service or for an outside call, any telephone handset on the extension that has a keypad can initiate a signal that is received and decoded in the master unit. When the master station receives such a signal, it disconnects the line to the telephone exchange from the extension and connects the telephone exchange to a circuit that detects incoming calls so that they can be signaled to users. The master station also sends a signal to each slave station that enables the intercom function. Speech originating from the handset that called for intercom is broadcast over a loud speaker at each slave station until one or more other handsets on the extension are picked up to respond to the page. The presence of an additional handset is detected at the master station which switches to the intercom mode. When the intercom use is complete and all handsets are returned in the cradles, the master station detects this fact and reestablishes the connection of the extension to the telephone exchange. The presence of a master station allows the addition of options such as speed dialing, overall alarming, and message recording.
|
