Method of arbitrating type II/type III CPE's during SCWID

• US 6,295,348 B1
• Filed: 11/14/1997
• Issued: 09/25/2001
• Est. Priority Date: 04/04/1997
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Becker, Christopher Henry, Bleile, Leonard George
• Primary Examiner(s): Matar, Ahmad F.
• Assistant Examiner(s): BUI, BING Q
• Application Number:
  US08/970,207
• Time in Patent Office: 1,411 Days
• Field of Search: 379/67.1, 379/142, 379/156, 379/196, 379/197, 379/198, 379/199, 379/229, 379/230, 379/377, 379/381, 379/382, 379/164, 379/215, 379/373, 379/399, 379/171, 379/177
• US Class Current: 379/199
• CPC Class Codes: H04M 1/573 Line monitoring circuits for detecting caller identification

Abstract

A method and apparatus for signalling a telephone switch to indicate the presence of a telephone of a pre-defined type on a subscriber loop. A subscriber loop is sensed to detect whether or not a telephone of a pre-defined type is connected to the subscriber loop. A first acknowledgement signal is transmitted to the telephone switch if the telephone of the pre-defined type is connected to the subscriber loop and off-hook and a second acknowledgement signal is transmitted to the telephone switch if the telephone of the pre-defined type is not off-hook.

Claims

1. A method of signalling a telephone switch to indicate the presence of a telephone of a predefined type on a subscriber loop, the method including the steps of:

a) sensing said subscriber loop to detect whether or not a telephone of a predefined type is connected to said subscriber loop;

b) transmitting to said telephone switch a first acknowledgement signal if said telephone of said predefined type is connected to said subscriber loop and off-hook and transmitting to said telephone switch a second acknowledgement signal if said telephone of said predefined type is not off-hook.

2. A method as claimed in claim 1 further including the step of detecting low frequency modulation on said subscriber loop, to detect whether or not said telephone of said predefined type is off-hook.

3. A method as claimed in claim 1 further including the step of monitoring voltage on said subscriber loop to detect signal transitions indicative of an extension-in-use.

4. A method as claimed in claim 3 further including the step of determining whether or not a signal transition indicative of an extension-in-use occurs within a predefined window of time.

5. A method as claimed in claim 4 further including the step of determining whether or not a signal transition indicative of an extension-in-use occurs within first or second predefined windows of time.

6. A method as claimed in claim 5 further including the step of transmitting said first acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said first window of time and transmitting said second acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said second window of time.

7. A method as claimed in claim 5 further including the step of detecting a Caller Alert Signal (CAS) on said subscriber loop and starting a timer in response to detection of said CAS signal.

8. A method as claimed in claim 7 further including the step of defining a pre-acknowledgment tone signal (pre-ack) delay period as a predefined period of time measured from detection of said CAS signal, said first and second windows of time falling within said pre-ack delay period.

9. A method as claimed in claim 8 further including the step of determining whether or not a signal transition indicative of an extension-in-use occurs within a first or second half of said pre-ack delay period.

10. A method as claimed in claim 9 further including the step of transmitting said first acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said first half of said pre-ack delay period and transmitting said second acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said second half of said pre-ack delay period.

11. A method as claimed in claim 8 further including the step of determining whether or not an extension is in use for a period of time less than or equal to said pre-ack delay period from receipt of said CAS signal and if so, setting an ADSI detect flag active according to whether or not the time elapsed since said CAS signal was detected is greater than said pre-ack delay period.

12. A method as claimed in claim 11 further including the step of disabling the transmission of said acknowledgement signal when said ADSI detect flag is set active.

13. A method as claimed in claim 8 further including the step of setting an ADSI detect flag active according to whether or not the time elapsed since said CAS signal was detected is greater than one-half of said pre-ack delay period.

14. A method as claimed in claim 13 further including the step of transmitting said acknowledgement signal after said pre-ack delay period.

15. A method as claimed in claim 13 further including the step of disabling the transmission of said acknowledgement signal when an ADSI detect flag is set active.

16. A method as claimed in claim 8 further including the step of placing said subscriber loop in an on-hook state for a for a time period equal to one-half of a pre-ack delay time period from receipt of said CAS signal.

17. An method as claimed in claim 16 further including the step of muting a receive path until FSK data is received.

18. A method as claimed in claim 16 further including the step of waiting a period of time equal to the sum of one-half of said pre-ack delay period and an ack length period from receipt of said CAS signal prior to placing said subscriber loop in an off hook state.

19. A method as claimed in claim 1 further including the step of disabling the transmission of said acknowledgment signal, and receiving Frequency Shift Keyed (FSK) data from said subscriber loop when an Analog Display Services Interface (ADSI) detect flag is set active.

20. A method as claimed in claim 1 wherein the step of transmitting said acknowledgment signal includes transmitting a Dual Tone Multi-Frequency (DTMF) A after a pre-ack delay period from receipt of said CAS signal.

21. A method as claimed in claim 1 wherein the step of transmitting said acknowledgement signal includes transmitting a DTMF D after a pre-ack delay period from receipt of said CAS signal.

22. An apparatus for signalling a telephone switch to indicate the presence of a telephone of a predefined type on a subscriber loop, the apparatus comprising:

a) a sensor for sensing said subscriber loop to detect whether or not a telephone of a predefined type is connected to said subscriber loop;

b) a transmitter for transmitting to said telephone switch a first acknowledgement signal if said telephone of said predefined type is connected to said subscriber loop and off-hook and transmitting to said telephone switch a second acknowledgement signal if said telephone of said predefined type is not off-hook.

23. An apparatus as claimed in claim 22 wherein said sensor is operable to sense low frequency modulation on said subscriber loop, to detect whether or not said telephone of said predefined type is off-hook.

24. An apparatus as claimed in claim 22 further including an analog to digital converter for, monitoring voltage on said subscriber loop to detect signal transitions indicative of an extension-in-use.

25. An apparatus as claimed in claim 24 further including a processor for determining whether or not a signal transition indicative of an extension-in-use occurs within a predefined window of time.

26. An apparatus as claimed in claim 25 further including a processor for determining whether or not a signal transition indicative of an extension-in-use occurs within first or second predefined windows of time.

27. An apparatus as claimed in claim 26 wherein said transmitter is operable to transmit said first acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said first window of time and transmit said second acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said second window of time.

28. An apparatus as claimed in claim 26 further including a CAS signal detector for detecting a CAS signal on said subscriber loop and a timer started in response to detection of said CAS signal.

29. An apparatus as claimed in claim 28 further including a microprocessor for defining a pre-ack delay period as a predefined period of time measured from detection of said CAS signal, said first and second windows of time falling within said pre-ack delay period.

30. An apparatus as claimed in claim 29 wherein said microprocessor is programmed to determine whether or not a signal transition indicative of an extension-in-use occurs within a first or second half of said pre-ack delay period.

31. An apparatus as claimed in claim 30 wherein said microprocessor is operable to direct said transmitter to transmit said first acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said first half of said pre-ack delay period and to transmit said second acknowledgement signal if said signal transition indicative of an extension-in-use occurs within said second half of said pre-ack delay period.

32. An apparatus as claimed in claim 29 further including a processor for determining whether or not an extension is in use for a period of time less than or equal to said pre-ack delay period from receipt of said CAS signal.

33. An apparatus as claimed in claim 32 wherein said microprocessor is programmed to set an ADSI detect flag active when the time elapsed since said CAS signal was detected is greater than said pre-ack delay period.

34. An apparatus as claimed in claim 32 wherein said microprocessor is programmed to disable the transmission of said acknowledgement signal when said ADSI detect flag is set active.

35. An apparatus as claimed in claim 29 wherein said microprocessor is programmed to set an ADSI detect flag active according to whether or not the time elapsed since said CAS signal was detected is greater than one-half of said pre-ack delay period.

36. An apparatus as claimed in claim 35 wherein said microprocessor is programmed to transmit said acknowledgement signal after said pre-ack delay period.

37. An apparatus as claimed in claim 35 further including an ADSI detect flag register for storing an ADSI detect flag and wherein said microprocessor is programmed to disable the transmission of said acknowledgement signal when said ADSI detect flag is set active.

38. An apparatus as claimed in claim 29 wherein said microprocessor is programmed to place said subscriber loop in an on-hook state for a for a time period equal to one-half of a pre-ack delay time period from receipt of said CAS signal.

39. An method as claimed in claim 38 wherein said microprocessor is programmed to mute a receive path until FSK data is received.

40. An apparatus as claimed in claim 38 wherein said microprocessor is programmed to wait a period of time equal to the sum of one-half of said pre-ack delay period and an ack length period from receipt of said CAS signal prior to placing said subscriber loop in an off hook state.

41. An apparatus as claimed in claim 22 further including an ADSI detect flag register for storing an ADSI detect flag, and a microprocessor operable to control said transmitter, for disabling the transmission of said acknowledgement signal, and for receiving FSK data from said subscriber loop when said ADSI detect flag is set active.

42. An apparatus as claimed in claim 22 wherein said microprocessor is programmed to direct said transmitter to transmit a DTMF A after a pre-ack delay period from receipt of said CAS signal.

43. An apparatus as claimed in claim 22 wherein said microprocessor is programmed to direct said transmitter to transmit a DTMF D after a pre-ack delay period from receipt of said CAS signal.