| 摘要 |
The security device comprises (i) a first connector ( 12 ) for connection to a telecommunications device ( 14; 15 ) such as a land-line telephone, mobile telephone or the modem of a computer, (ii) a second connector ( 16 ) connected to a telecommunications line ( 18 ), and (iii) a normally closed switch ( 20, 21 ) having a closed position in which a signal pathway ( 22, 23 ) within the security device between the first connector ( 12 ) and the second connector ( 16 ) is enabled and an open position in which the signal pathway ( 22, 23 ) is interrupted. A control device ( 24, 25 ) for controls the position of the switch ( 20, 21 ). A programmable memory ( 26, 27 ) stores allowed signal sequences and at least one authorised pass number. A comparator ( 30 ) is in operative connection with the control device ( 24, 25 ) and compares signals on the pathway ( 22, 23 ) with the allowed stored signal sequences. The control device ( 24, 25 ) opens the switch ( 20, 21 ) when a signal on the pathway ( 22, 23 ) does not match one of the stored signal sequences. A programmer ( 32 ) receives pass numbers and programming signals from a remote telecommunications device ( 52 ) via the telecommunications line ( 18 ). The programmer ( 32 ) includes an authorised pass number recognition device ( 34 ) for comparing a received pass number with the authorised pass numbers stored in the memory ( 26,27 ). The memory ( 26, 27 ) can be reprogrammed only when an authorised pass number is received.
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