Telephone line security device (TLSD): article

This paper presents the invention relates to a telephone line security. The device has been developing to preventing unauthorized use of the subscriber’s telephone set. Act as an inhibit device to isolate unauthorized make a call. The device has a personal identification number (PIN) storing in the PIC microprocessor, personal identification number (PIN) is a secure number which is used every time when make a call. The device includes circuitry which able to disconnect the transmitting element from the telephone if the personal identification number given are incorrect. TLSD was tested and develops based on public switched telephone network (PSTN) architecture. An emergency service number is obtainable at any time even when other calls are inhibited.