Three-way telephone call prevention system and method

• US 7,079,636 B1
• Filed: 09/20/2002
• Issued: 07/18/2006
• Est. Priority Date: 09/21/2001
• Status: Active Grant

• Current Assignee: Securus Technologies Incorporated (Securus Special Investments LLC)
• Original Assignee: Evercom Systems Incorporated (Securus Special Investments LLC)
• Inventors: Lord, Michael, McNitt, George
• Primary Examiner(s): Bui, Bing Q.
• Application Number:
  US10/252,956
• Time in Patent Office: 1,397 Days
• Field of Search: 379/189, 379/200, 379/207.01, 379/215.01
• US Class Current: 379/189
• CPC Class Codes: H04M 3/2281 Call monitoring, e.g. for law enforcement purposes; Call tracing; Detection or prevention of malicious calls

Abstract

Discloses are systems and methods for detecting undesired call activity. Preferred embodiment systems and methods comprise detecting a call signal level, determining if the call signal level is below a predetermined silence level threshold, and measuring a duration the call signal level remains below the predetermined silence level threshold.

Claims

1. A system for detecting undesired call activity, said system comprising:

means for detecting a call signal level;

means for determining if said call signal level is below a predetermined silence level threshold; and

means for measuring a duration said call signal level remains below said predetermined silence level threshold.

2. The system of claim 1, further comprising:

means for determining if said measured duration said call signal level remains below said predetermined silence level threshold exceeds a minimum silence duration.

3. The system of claim 2, wherein said minimum silence duration is operator selectable.

4. The system of claim 2, wherein said minimum silence duration is approximately 13,000 milliseconds.

5. The system of claim 2, further comprising:

means for determining if said measured duration said call signal level remains below said predetermined silence level threshold exceeds a maximum silence duration.

6. The system of claim 5, wherein said maximum silence duration is operator selectable.

7. The system of claim 5, wherein said maximum silence duration is approximately 16,000 milliseconds.

8. The system of claim 1, wherein said predetermined silence level threshold is operator selectable.

9. The system of claim 1, wherein said predetermined silence level threshold is approximately −

56 dB.

10. The system of claim 1, further comprising:

means for determining if said call signal level is below a predetermined high level threshold, wherein said means for determining if said call signal level is below a predetermined silence level threshold and said means for measuring a duration said call signal level remains below said predetermined silence level threshold are operable under control of said means for determining if said call signal level is below said predetermined high level threshold.

11. The system of claim 10, wherein said predetermined high level threshold comprises a minimum conversation level threshold.

12. The system of claim 11, wherein said minimum conversation level threshold is approximately −

53 dB and said predetermined silence level threshold is approximately −

56 dB.

13. A method for detecting undesired call activity, said method comprising:

detecting a call signal level;

determining if said call signal level is below a predetermined silence level threshold; and

measuring a duration said call signal level remains below said predetermined silence level threshold.

14. The method of claim 13, further comprising:

determining if said measured duration said call signal level remains below said predetermined silence level threshold exceeds a minimum silence duration.

15. The method of claim 14, wherein said minimum silence duration is operator selectable.

16. The method of claim 14, further comprising:

determining if said measured duration said call signal level remains below said predetermined silence level threshold exceeds a maximum silence duration.

17. The method of claim 13, wherein said predetermined silence level threshold is approximately −

56 dB.

18. The method of claim 13, further comprising:

determining if said call signal level is below a predetermined high level threshold, wherein said determining if said call signal level is below a predetermined silence level threshold and said measuring a duration said call signal level remains below said predetermined silence level threshold are operable upon said determining said call signal level is below said predetermined high level threshold.

19. The method of claim 18, wherein said predetermined high level threshold comprises a minimum conversation level threshold.

20. The method of claim 19, wherein said minimum conversation level threshold is approximately −

53 dB and said predetermined silence level threshold is approximately −

56 dB.

21. A method for detecting undesired call activity, said method comprising:

specifying a predetermined high signal level and a predetermined low signal level;

determining, without detecting a signal associated with a hook flash, when a call signal level drops below said high signal level;

initiating a signal listening algorithm to determine if said call signal level drops below said low signal level;

measuring a duration of time said call signal remains below said low signal level; and

determining if said duration reaches a predetermined value, indicating said undesired call activity.