Patents

US 7826604 B2: Three-way call detection using steganography

Granted

2010-11-02

Filed

2007-07-24 application 11878370

Type

Utility · 12 claims

Elsewhere

Google Patents ↗ · USPTO patent document ↗ · USPTO Patent Center record ↗

Abstract

Three-way call detection is an important component of correctional facility telephone equipment because it helps restrict calling access by certain persons to certain restricted telephone numbers. Various three-way call detection methods exist, but all of these implementations suffer from one major limitation—the detection accuracy is not as high as is desired by the industry. The present invention improves detection accuracy, using “steganography.” Steganography involves hiding one set of data or signals within another signal or carrier in such a way that its presence is virtually imperceptible to the end recipient, and potential even the originator of the carrier signal. Television producers use steganographic methods to encode data in video signals for security, distribution monitoring, piracy-control, and other reasons. The present invention involves a device that connects to a telephone, either at the line or handset interfaces, and produces a known signal that is steganographically hidden within the user's normal voice signal. Detection equipment, residing at another location, monitors signals on telephone calls and tests for the presence of the hidden signal or data generated by the invention. Once detection is achieved, appropriate action, such as terminating or recording the call, may be taken. Improved accuracy is achieved by choosing the appropriate hidden signal(s)—ones that never occur in the course of normal conversation and never get generated by telephone company equipment. Once detected, the presence of the signal guarantees the call was made to the restricted party from a particular phone line.

Source: PVGPATDIS, file of 2026-04-10 (ipg101102.xml).

Assignees

Inventors

CPC categories

Cooperative Patent Classification, as currently assigned (one row per subclass).

Assignments and security interests

Documents recorded with the USPTO Assignment Recordation Branch that list this patent. A security interest is a lender’s claim on the patent as collateral; a release ends it.

USPTO bulk data: PatentsView granted patents, disambiguated (PVGPATDIS) for patents, assignees, inventors, places and CPC categories; the USPTO Patent Assignment Dataset (ECORSEXC) for assignments and security interests. Patents filed in the last 20 years. No claims or full text. Links to other records are by name (and state): EXACT means the identical full name and state; FUZZY means a looser name match, with the confidence shown.