Telephone line security system

• Main Author: MURRAY; THORNTONE E
• Format: Patent
• Language: English
• Published: 23.10.1990
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS; TELEPHONIC COMMUNICATION

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.