METHOD, APPARATUS AND SYSTEM FOR FILTERING INCOMING TELEPHONE CALLS

摘要

The system (300) for restricting telephone access to a predetermined set of telephone numbers having a PSTN access terminal (201), connection circuit (210), CID signal decoder (220), caller-id (CID) number comparator (230), off-hook detector (240), and secured modem/subscriber equipment (250). Connection circuit (210) includes an input terminal (212), an output terminal (218), connect enable input, and connect disable input. CID signal decoder (220) has input connected to the PSTN and output connected to the input of the CID number comparator (230), the output of the CID comparator connected to the connect enable input of the connection circuit. The connection circuit (210) coupled to the secured modem/subscriber equipment input (252) and the off-hook detector input through node where the off-hook detector output is received by the connect disable input. The system only allows a call to be completed if the calling number matched with the number stored in memory.