System and method for detecting three-way call circumvention attempts

• US 20100202595A1
• Filed: 02/12/2009
• Published: 08/12/2010
• Est. Priority Date: 02/12/2009
• Status: Active Grant

• Current Assignee: Value-Added Communications Incorporated
• Original Assignee: Value-Added Communications Incorporated
• Inventors: Kesterson, Fred, Hodge, Stephen L., Seyfetdinov, Serge
• Granted Patent: US 8,630,726 B2
• Time in Patent Office: Days
• US Class Current: 379/32.10
• CPC Class Codes: H04M 2203/6027 Fraud preventions
• CPC Class Codes: H04M 3/205 Eavesdropping prevention - indication of insecurity of line or network
• CPC Class Codes: H04M 3/2281 Call monitoring, e.g. for law enforcement purposes; Call tracing; Detection or prevention of malicious calls
• CPC Class Codes: H04M 3/42314 in private branch exchanges

Abstract

Disclosed is a three-way call detection system and method for use with a telephone management system. Specifically, a three-way call detection system and method for detecting continuous noise indicative of an attempt to mask a three-way call attempt. The continuous noise detection system and method may be stand alone or used in conjunction with any existing three-way call detection system and method.

Claims

1. A method for detecting an attempt to mask a three-way call, said method comprising the steps of:

monitoring an audio stream;

detecting when a power level of said audio stream exceeds a pre-determined threshold;

calculating an elapsed time when said power level of said audio stream exceeds said pre-determined threshold; and

determining whether said elapsed time exceeds a maximum allowable period of time.

2. The method of claim 1, wherein said power level is the signal power of said audio stream.

3. The method of claim 2, further comprising the step of determining whether said signal power is evenly distributed across said elapsed time.

4. The method of claim 1, wherein said pre-determined threshold is at least approximately −

20 decibels (dBm).

5. The method of claim 1, wherein said elapsed time is at least approximately 1500 milliseconds (ms).

6. A method for detecting an attempt to mask a three-way call, said method comprising the steps of:

monitoring an audio stream;

detecting when a power level of said audio stream falls below a pre-determined threshold;

detecting when said power level of said audio stream exceeds said pre-determined threshold;

detecting the next occurrence of said power level of said audio stream falling below said pre-determined threshold;

calculating an elapsed time between said power level of said audio stream exceeding said pre-determined threshold and said power level of said audio stream falling below said pre-determined threshold; and

comparing said elapsed time to a pre-determined maximum allowable period of time.

7. The method of claim 6, wherein power level is the signal power of said audio stream.

8. The method of claim 6, wherein said method further comprises the step of:

determining a false indication of a continuous noise three-way call circumvention attempt utilizing a continuous noise detection algorithm.

9. The method of claim 8, wherein said continuous noise detection algorithm analyzes said signal power as a PCM signal.

10. The method of claim 9, wherein said continuous noise detection algorithm includes a power distribution filter algorithm and a zero crossing filter algorithm.

11. The method of claim 10, wherein said power distribution filter algorithm detects when said signal power is not evenly distributed across said time period.

12. The method of claim 10, wherein said zero crossing filter algorithm calculates whether the zero-crossing rate of said signal power is below a pre-determined threshold of human speech.

13. The method of claim 9, wherein said predetermined threshold is at least approximately −

20 dBm.

14. The method of claim 6, wherein said elapsed time is 1500 ms.

15. An apparatus for detecting an attempt to mask a three-way call, said apparatus comprising:

an interface for receiving audio streams from a telephone line;

a microprocessor coupled to said interface for detecting when a power level of said audio stream exceeds a pre-determined threshold;

wherein said microprocessor monitors said audio stream for a pre-determined time; and

wherein said microprocessor determines whether said power level of said audio stream exceeded said pre-determined threshold for the duration of said predetermined time.

16. The apparatus of claim 15, wherein power level is the signal power of said audio stream.

17. The apparatus of claim 15, wherein said microprocessor includes a continuous noise detection algorithm for detecting a false three-way call.

18. The apparatus of claim 17, wherein said continuous noise detection algorithm includes a power distribution filter algorithm and a zero crossing filter algorithm.

19. The apparatus of claim 18, wherein said power distribution filter algorithm detects when said signal power is not evenly distributed across said pre-determined time.

20. The apparatus of claim 20, wherein said zero crossing filter algorithm calculates whether the zero-crossing rate of said signal power is below a pre-determined threshold of human speech.