| 摘要 |
An apparatus for selectively allowing calls to a device, such as a fax machine, that may receive calls on a signal line. The apparatus is arranged to, upon detecting an incoming call, initiate a blocking period during which the incoming call is prevented from reaching the device, and to terminate the blocking period when a predetermined threshold, for example a number of rings or period of time, has elapsed, and upon termination of the blocking period to initiate said enabled time period. Hence, incoming calls are not prevented from reaching the device if their duration exceeds the predetermined threshold. The apparatus helps to reduce the number of unwanted calls being received since spam calls commonly emanate from automated sending devices with a ring duration that is typically less than that of legitimate callers. |
