Method and apparatus for detecting an attempted three-way conference call on a remote telephone

• US 5,539,812 A
• Filed: 11/08/1994
• Issued: 07/23/1996
• Est. Priority Date: 07/29/1992
• Status: Expired due to Term

• Current Assignee: Securus Technologies Incorporated (Securus Special Investments LLC)
• Original Assignee: Tnetix Incorporated
• Inventors: Schott, Alan K., Kitchin, Dwight W., Johnson, John C., Smith, Clive L.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Hunter, Daniel S.
• Application Number:
  US08/336,001
• Time in Patent Office: 623 Days
• Field of Search: 379/93, 379/112, 379/114, 379/123, 379/132, 379/144, 379/145, 379/155, 379/157, 379/158, 379/159, 379/162, 379/189, 379/190, 379/199, 379/201, 379/211, 379/286, 379/377 , 379/386, 379/424
• US Class Current: 379/189
• CPC Class Codes: H04M 1/53 Generation of additional signals, e.g. additional pulses
• CPC Class Codes: H04M 1/66 with means for preventing unauthorised or fraudulent calling verifying user identity or authority in secret or secure digital communications H04L9/32
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573
• CPC Class Codes: H04M 2203/5018 Initiating a conference during a two-party conversation, i.e. three-party-service or three-way-call computer conference organisation arrangements H04L12/1818
• CPC Class Codes: H04M 3/2272 Subscriber line supervision circuits, e.g. call detection circuits
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04M 3/568 audio processing specific to telephonic conferencing, e.g. spatial distribution, mixing of participants echo suppression in two-way loud-speaking telephone systems H04M9/02; sound field processing per se H04S7/30

Abstract

Methods and apparatus for use in connection with a telecommunication between a local telephone and a remote telephone, which are capable of detecting whether one of the parties to the communication has attempted to initiate a three-way, i.e., conference, call by using a hook-flash signal. The apparatus includes a low pass filter for passing energy having frequencies below about 500 Hz, and an energy detector for detecting a specific electrical energy pulse characteristic of the hook-flash having passed through the low pass filter. The existence of the hook-flash is confirmed by digital signal processing equipment which identifies a rapid drop-off in energy also characteristic of the hook-flash signal. Optionally, the hook-flash may be further confirmed by including software for cooperating with the energy detector to ascertain whether sound has occurred in the telecommunication during a predetermined period following the first hook-flash signal.

Claims

1. An apparatus connected to a telecommunication between a local telephone in telecommunication with a remote telephone, wherein one of said telephones has a three-way calling service which is not associated with the apparatus, which apparatus is capable of determining whether the party using the telephone with three-way calling service has performed a specific act that is consistent with an attempt to initiate a three-way call utilizing a hook-flash signal comprising:

means for the detection of an energy pulse generated by the telephone having the three-way calling service, said pulse having a frequency characteristic of the hook-flash signal;

first means for confirming the existence of the hook-flash by analyzing the energy pulse to determine if there is a rapid drop-off in energy which is a further characteristic of the hook-flash signal; and

response means for implementing a predetermined response when said energy pulse is detected and confirmed.

2. The apparatus according to claim 1 in which the apparatus is connected in the telecommunication at a point between the local telephone and the first switch in the local exchange.

3. The apparatus according to claim 2 in which the first means for confirming the hook-flash comprises digital signal processing means for analyzing the energy pulse to determine if there is a rapid drop-off in energy which is a further characteristic of the hook-flash signal.

4. The apparatus according to claim 2 in which the means for detecting and the means for confirming the hook flash comprises:

means for filtering the energy to a bandwidth less than approximately 500 Hz;

means for calculating the absolute value of the hook flash signal;

means for calculating the moving average of the signal;

means for determining whether the signal is greater than a predetermined minimum; and

means for determining whether there is a rapid drop off in the energy of the signal, if the energy of the signal is greater than the predetermined minimum, by comparing a current sample of the signal to a previous sample of the signal.

5. The apparatus according to claim 4 further comprising second means for confirming the existence of the hook-flash by window analyzation.

6. The apparatus according to claim 4 in which the means for the detection of an energy pulse generated by the telephone having the three-way calling service includes low pass filtering means for passing energy having a frequency between approximately 100 and 300 Hz.

7. The apparatus according to claim 4 in which the low pass filtering means is accomplished with digital signal processing.

8. The apparatus according to claim 4 in which the means for detecting and the first means for confirming are digital signal processing means.

9. The apparatus according to claim 8 in which the digital signal processing means analyzes the signal at a rate of once every 39 mS.

10. The apparatus according to claim 9 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.05 to 0.17.

11. The apparatus according to claim 9 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.078.

12. The apparatus according to claim 8 further comprising second means for confirming the existence of the hook-flash signal by window analyzation.

13. The apparatus according to claim 12 in which said window analyzation means includes:

timer means for cooperating with said energy detection means so that said timer means begins running for a first pre-determined time period when a specific energy pulse is detected and confirmed by said first confirmation means;

sound detection means for detecting sound during the telecommunication and for cooperating with said timer means so that said sound detection means is activated at the end of the first predetermined period for a second predetermined maximum time period; and

means for activating the response means if sound is undetected during the second predetermined period, the undetection of which provides an indication that the remote party has performed a specific act that is consistent with an attempt to initiate a three-way call.

14. The apparatus according to claim 13 further including means for echo cancellation or for muting the sound from the telephone other than the one which has three-way call services associated with it during the second predetermined period.

15. The apparatus according to claim 4 in which the response means includes means for implementing at least one predetermined response selected from the group consisting of:

means for terminating the telecommunication between the local and remote parties;

means for playing a pre-recorded message;

means for generating a tone which is heard by one or more parties to the telecommunication;

means for muting the local telephone; and

means for recording the date and time of the attempt to initiate the three-way call.

16. The apparatus according to claim 4 in which the response means comprises means for terminating the telecommunication between the local and remote parties.

17. The apparatus according to claim 1 in which the apparatus is connected in the telecommunication at a point in the network after the telecommunication from the local telephone reaches the initial switch at the local exchange.

18. The apparatus according to claim 17 in which the first means for confirming the hook-flash comprises digital signal processing means for analyzing the energy pulse to determine if there is a rapid drop-off in energy which is a further characteristic of the hook-flash signal.

19. The apparatus according to claim 17 in which the means for detecting and the means for confirming the hook flash comprises:

means for filtering the energy to a bandwidth less than approximately 500 Hz;

means for calculating the absolute value of the hook flash signal;

means for calculating the moving average of the signal;

means for determining whether the signal is greater than a predetermined minimum; and

means for determining whether there is a rapid drop off in the energy of the signal, if the energy of the signal is greater than the predetermined minimum, by comparing a current sample of the signal to a previous sample of the signal.

20. The apparatus according to claim 19 further comprising second means for confirming the existence of the hook-flash by window analyzation.

21. The apparatus according to claim 19 in which the means for the detection of an energy pulse generated by the telephone having the three-way calling service includes low pass filtering means for passing energy having a frequency between approximately 100 and 300 Hz.

22. The apparatus according to claim 19 in which the low pass filtering means is accomplished with digital signal processing.

23. The apparatus according to claim 19 in which the means for detecting and the first means for confirming are digital signal processing means.

24. The apparatus according to claim 19 in which the digital signal processing means analyzes the signal at a rate of once every 39 mS.

25. The apparatus according to claim 24 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.05 to 0.17.

26. The apparatus according to claim 24 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.078.

27. The apparatus according to claim 23 further comprising second means for confirming the existence of the hook-flash signal by window analyzation.

28. The apparatus according to claim 27 in which said window analyzation means includes:

timer means for cooperating with said energy detection means so that said timer means begins running for a first pre-determined time period when a specific energy pulse is detected and confirmed by said first confirmation means;

sound detection means for detecting sound during the telecommunication and for cooperating with said timer means so that said sound detection means is activated at the end of the first predetermined period for a second predetermined maximum time period; and

means for activating the response means if sound is undetected during the second predetermined period, the undetection of which provides an indication that the remote party has performed a specific act that is consistent with an attempt to initiate a three-way call.

29. The apparatus according to claim 28 further including means for echo cancellation or for muting the sound from the telephone other than the one which has three-way call services associated with it during the second predetermined period.

30. The apparatus according to claim 19 in which the response means includes means for implementing at least one predetermined response selected from the group consisting of:

means for terminating the telecommunication between the local and remote parties;

means for playing a pre-recorded message;

means for generating a tone which is heard by one or more parties to the telecommunication;

means for muting the local telephone; and

means for recording the date and time of the attempt to initiate the three-way call.

31. The apparatus according to claim 19 in which the response means comprises means for terminating the telecommunication between the local and remote parties.

32. An apparatus connected to a telecommunication between a local telephone in telecommunication with a remote telephone, said connection being made at a point in the network after the telecommunication from the local telephone reaches the initial switch at the local exchange, wherein one of said telephones has a three-way calling service which is not associated with the apparatus, which apparatus is capable of determining whether a party using the telephone with the three-way calling service has performed a specific act that is consistent with an attempt to initiate a three-way call utilizing a hook-flash signal comprising:

low pass filtering means for passing energy having a frequency less than about 500 Hz;

means for the detection of an energy pulse generated by the telephone having the three-way calling service having a frequency less than about 500 Hz and above a pre-determined threshold which is characteristic of the hook-flash signal;

first means for confirming the existence of the hook-flash by analyzing the energy pulse to determine if there is a rapid drop-off in energy of the pulse which is a further characteristic of the hook-flash signal;

second means for confirming the existence of the hook-flash by window analyzation; and

response means for implementing a predetermined response when said energy pulse is detected and confirmed by said first and said second means for confirming.

33. The apparatus according to claim 32 in which the low pass filtering means passes energy having a frequency between approximately 100 and 300 Hz.

34. The apparatus according to claim 32 in which the low pass filtering means passes energy having a frequency between approximately 200 and 300 Hz.

35. The apparatus according to claim 32 in which the first means for confirming the hook-flash comprises digital signal processing means for analyzing the energy pulse to determine if there is a rapid drop-off in energy which is a further characteristic of the hook-flash signal.

36. The apparatus according claim 32 in which the means for the detection of an energy pulse characteristic of the hook-flash signal and the first means for confirming the existence of the hook-flash comprise digital signal processing:

means for calculating the absolute value of the hook flash signal;

means for calculating the moving average of the signal;

means for determining whether the signal is greater than a predetermined minimum;

means for determining whether there is a rapid drop off in the energy of the signal, if the signal is greater than the predetermined minimum, by comparing current sample of the signal to a previous sample of the signal.

37. The apparatus according to claim 36 in which the low pass filtering means is accomplished with digital signal processing.

38. The apparatus according to claim 36 in which the means for detecting and the first means for confirming comprises digital signal processing means.

39. The apparatus according to claim 38 in which the digital signal processing means analyzes the signal at a rate of once every 39 Ms.

40. The apparatus according to claim 39 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.05 to 0.17.

41. The apparatus according to claim 39 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.078.

42. The apparatus according to claim 36 in which said window analyzation means includes:

timer means for cooperating with said energy detection means so that said timer means begins running for a first pre-determined time period when a specific energy pulse is detected and confirmed by said first confirmation means;

sound detection means for detecting sound during the telecommunication and for cooperating with said timer means so that said sound detection means is activated at the end of the first predetermined period for a second predetermined maximum time period; and

means for activating the response means if sound is undetected during the second predetermined period, the undetection of which provides an indication that the remote party has performed a specific act that is consistent with an attempt to initiate a three-way call.

43. The apparatus according to claim 42 further including means for echo cancellation or for muting the sound from the telephone other than the one which has three-way call services associated with it during the second predetermined period.

44. The apparatus according to claim 36 in which the response means includes means for implementing a predetermined response selected from the group consisting of:

means for terminating the telecommunication between the local and remote parties;

means for playing a pre-recorded message;

means for generating a tone which is heard by one or more parties to the telecommunication;

means for muting the local telephone; and

means for recording the date and time of the attempt to initiate the three-way call.

45. The apparatus according to claim 36 in which the response means includes comprises means for terminating the telecommunication between the local and remote parties.

46. A method for determining whether a remote party using a remote telephone in telecommunication with local telephone equipment, wherein said remote telephone has a three-way calling service which is not associated with the apparatus, has performed a specific act that is consistent with an attempt to initiate a three-way call utilizing a hook-flash signal comprising:

detecting an energy pulse generated by the telephone having the three-way calling service, said pulse having a frequency characteristic of the hook-flash signal;

confirming the existence of the hook-flash by analyzing the energy pulse to determine if there is a rapid drop-off in energy which is a further characteristic of the hook-flash signal; and

responding in a predetermined response manner when said energy pulse is detected and confirmed.

47. The method of claim 46 wherein the step of detecting energy comprises:

filtering the energy received by the local telephone equipment to a frequency range characteristic of the hook-flash signal; and

detecting a specific electrical energy pulse having passed through the filter.

48. The method of claim 46 wherein the steps of detecting an energy pulse and for confirming the detection comprise:

filtering the energy pulse to pass filtered energy in a frequency range of less than approximately 500 Hz;

calculating the absolute value of the filtered energy;

calculating the moving average of the signal;

determining whether the signal is greater than a predetermined minimum,

determining whether there is a rapid drop off in the energy of the signal, if the signal is greater than the predetermined minimum, by comparing the current sample of the signal to a previous sample of the signal.

49. The method of claim 48 in which the filtering step passes filtered energy in a frequency range of approximately 100 to 300 Hz.

50. The method of claim 48 in which the filtering step passes filtered energy in a frequency range of approximately 200 to 300 Hz.

51. The method according to claim 48 in which the detecting and confirming occurs by analyzing the signal at a rate of once every 39 mS.

52. The apparatus according to claim 51 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.05 to 0.17.

53. The apparatus according to claim 51 in which the rapid drop-off in energy is characterized by having an effective slope of approximately 0.078.

54. The method of claim 48 including further confirming the existence of the hook-flash by:

monitoring the telecommunication for a predetermined time period which commences after the existence of the pulse is detected and confirmed to detect a specific event occurring during that time period the detection of which further confirms whether the remote party has performed a specific act that is consistent with an attempt to initiate a three-way call and

the responding in a predetermined manner occurs when the remote party'"'"'s performance of a specific act that is consistent with an attempt to initiate a three-way call has been detected, confirmed and further confirmed by said monitoring.

55. The method of claim 53 including further confirming the existence of the hook-flash by:

monitoring the telecommunication for a predetermined time period which commences after the existence of the pulse is detected and confirmed to detect a specific event occurring during that time period the detection of which further confirms whether the remote party has performed a specific act that is consistent with an attempt to initiate a three-way call and

the responding in a predetermined manner occurs when the remote party'"'"'s performance of a specific act that is consistent with an attempt to initiate a three-way call has been detected, confirmed and further confirmed by said monitoring.

56. The method of claim 55 further comprising the step of preventing signals originating with the local telephone equipment from interfering with the further confirming of the hook-flash signal.

57. The method of claim 56 wherein the step of preventing signals originating with the local telephone equipment from interfering with the further confirming of the hook-flash signal is accomplished by echo cancellation.

58. The method of claim 56 wherein the step of preventing signals originating with the local telephone equipment from interfering with the further confirming of the hook-flash signal is accomplished by:

muting the local telephone equipment when an energy pulse is detected; and

un-muting the local telephone equipment at the conclusion of the predetermined window.

59. The apparatus according to claim 55 in which the step of responding comprises at least one step selected from the group consisting of:

terminating the telecommunication between the local and remote parties;

playing a pre-recorded message;

generating a tone which is heard by one or more parties to the telecommunication;

muting the local telephone; and

recording the date and time of the attempt to initiate the three-way call.

60. The apparatus according to claim 55 in which the step of responding comprises terminating the telecommunication between the local and remote parties.