| 摘要 |
<p>A respective signalling transmitter (112) is enabled by the polarity reversal on the tip and ring lines and couples a unique identification signal to these lines. A respective signalling receiver (118) responds to an interrogate signal to cause the line adaptor circuit to send a unique identification signal to the subscriber line. A line switch transistor (116) responds to the unique identification signal to enable the line adaptor circuit so that ringing current can be received from the line at the enabled line adaptor circuit and so that none of the disabled line adaptor circuits receives the ringing current. - The switch transistor cooperates with the signalling receiver for receiving the identification signals so that only the calling subscriber and the uniquely-identified subscriber are coupled to the subscriber line. All other subscribers on the multiparty line are disabled and uncoupled so as to maintain the privacy of communication on the line.</p> |
