Telephone line security system

• US 4,965,459 A
• Filed: 05/26/1989
• Issued: 10/23/1990
• Est. Priority Date: 05/26/1989
• Status: Expired due to Fees

• Current Assignee: Thorntone E. Murray
• Original Assignee: Thorntone E. Murray
• Inventors: Murray, Thorntone E.
• Primary Examiner(s): BROWN, THOMAS
• Application Number:
  US07/125,260
• Time in Patent Office: 515 Days
• Field of Search: 379/200, 379/188, 379/189, 379/445
• US Class Current: 379/189
• CPC Class Codes: H04M 1/677 Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers
• CPC Class Codes: Y10S 379/903 Password

Abstract

A telephone line security system which provides for telephone subscriber designation of secure digit sequences, exception digit sequences, and authorization digit sequences, wherein the user must necessarily assert a subscriber designated authorization digit sequence onto the telephone line in order to place a telephone call to a telephone number containing a secure digit sequence, unless the subscriber has designated an exception digit sequence to the secure digit sequence. The telephone line system is contained within a secure housing and comprises a telephone line interface circuit, a dial tone detection circuit, a digit determination circuit, a secure digit sequence programming circuit, an authorization digit sequence programming circuit, an exception digit sequence programming circuit, a sequence determination circuit, a system reset circuit, a secure digit sequence detection circuit, an authorization digit sequence detection circuit, an exception digit sequence detection circuit, a telephone call authorization circuit, and a power supply circuit. Designation of all digit sequences is by subscriber programmable circuit and maximum control of what telephone calls may be made, and by what user, on the subscriber'"'"'s telephone line is maintained.

Claims

1. A telephone line security system which controls the telephone numbers which may be called on a telephone line, comprising:

a telephone line interface circuit which is connected to the telephone line and provides electrical isolation between the telephone line and the telephone line security system;

a dial tone detection circuit which is connected to the telephone line interface circuit that provides an output signal when a dial tone is detected on the telephone line;

a digit determination circuit which is connected to the telephone line interface circuit and provides an output unique to each digit of a telephone number asserted onto the telephone line;

a secure digit sequence programming circuit which is subscriber programmable and stores each sequence of digits occurring in telephone numbers which are to be prohibited;

an authorization digit sequence programming circuit which is subscriber programmable and stores each sequence of digits which are selected to be code number sequences;

an exception digit sequence programming circuit which is subscriber programmable and stores each sequence of digits which occur in telephone numbers which are selected to be exceptions to the sequences of digits occurring in telephone numbers which are to be prohibited;

a sequence determination circuit which produces an output upon receipt of each input from the digit determination circuit, which output indicates the number of the input within a sequence of the inputs;

a system reset circuit which produces an output that resets a telephone call authorization circuit upon initial application of power to the telephone line security system;

a secure digit sequence detection circuit which produces an output if the sequence of digits input from the digit determination circuit coincides with a sequence of digits stored in the secure digit sequence programming circuit;

an authorization digit sequence detection circuit which produces an output if the sequence of digits input from the digit determination circuit coincides with a sequence of digits stored in the authorization digit sequence programming circuit;

an exception digit sequence detection circuit which produces an output if the sequence of digits input from the digit determination circuit coincides with a sequence of digits stored in the exception digit sequence programming circuit;

said telephone call authorization circuit is connected to the telephone line interface circuit and asserts an output onto the telephone line which makes communication impossible if the secure digit sequence determination circuit has an output, if the exception digit sequence determination circuit does not have an output, and the telephone call placed immediately prior was not of a sequence of digits which caused the authorization digit sequence determination circuit to produce an output.

2. The telephone line security system as described in claim 1 further comprising a power supply circuit which supplies all necessary voltages and currents for the operation of the telephone line security system.

3. The telephone line security system as described in claim 1 further comprising a housing which is attached to a telephone line connection box, provides a lockable, hinged door on a side of the housing, provides a connector for connection to the telephone line on the side of the housing connected to the telephone line connection box, and provides a connector for connection of a telephone cable on a side of the housing other than the side of the housing which is connected to the telephone line connection box.