| 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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