| 摘要 |
<p>Telephone trunk barring device, characterised in that it is to be associated with a telephone and interposed between a dialling means (16) and a signal generator means (18) arranged to send signals corresponding to dialled digits on an output (30, 32) of the telephone which is arranged to be connected to a telephone line, the telephone trunk barring device comprising a decoder means (12) connected to an output of the dialling means (16) of the telephone to analyse the signals corresponding to the dialled digits transmitted by the dialling means (16), the signal generator means (18) connected to the decoder means (12) for transmission of a line signal to the telephone line which is a signal corresponding to the dialled digits and a control means (12) arranged between the decoder means (12) and the signal generator means (18) to selectively block the transmission of some signals corresponding to the dialled digits.</p> |
