Cable modem with voice processing capability

• US 7,933,295 B2
• Filed: 09/12/2001
• Issued: 04/26/2011
• Est. Priority Date: 04/13/1999
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Lukas, Robert M., Unger, Kenneth J., Borazjani, Ramin, Hartman, David, Brooks, Todd L., Lansing, Shane P., Rabenko, Theodore F., Thi, James C., Miller, Kevin L., Lee, Robert J.
• Primary Examiner(s): Wong; Warner
• Application Number:
  US09/949,811
• Publication Number:
  US 20020061012A1
• Time in Patent Office: 3,513 Days
• Field of Search: 370/352, 370/389, 370/39.07, 370/465, 370/94.4, 370/406.01, 370/395.62, 370/503, 370/509, 370/419, 370/359, 370/463, 370/494, 370/495, 348/14.01, 379/410, 725/119
• US Class Current: 370/493
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 3/234 using double talk detection
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04L 12/28 characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] wireless communication networks H04W ; arrangements for dividing the transmission path H04W40/00
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/2834 Switching of information between an external network and a home network access arrangements H04L12/2856
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 7/0087 Network planning or provisioning
• CPC Class Codes: H04M 7/125 Details of gateway equipment
• CPC Class Codes: H04M 9/08 Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence

Abstract

A network gateway is configured to facilitate on line and off line bi-directional communication between a number of near end data and telephony devices with far end data termination devices via a hybrid fiber coaxial network and a cable modem termination system. The described network gateway combines a QAM receiver, a transmitter, a DOCSIS MAC, a CPU, a voice and audio processor, a voice synchronizer, an Ethernet MAC, and a USB controller to provide high performance and robust operation.

Claims

1. A cable modem, comprising:

a network port configured to interface with a cable head end;

a telephony port configured to interface with a telephony device;

a data port configured to interface with a data terminal; and

a processor, coupled to each of the ports, configured to;

differentiate between a voice signal associated with a voice call and a voice signal associated with a machine call,

determine whether a voice signal received from the network port is destined for the data port or the telephony port based on whether the voice signal received from the network port is associated with the voice call or the machine call, and

send the voice signal received from the network port to one of the data port and the telephony port based on such determination,

wherein the processor comprises;

an echo canceller operable to cancel a cable head end echo on a voice signal received from the telephony port, wherein the echo canceller comprises;

a filter operable to adaptively filter the voice signal received from the network port, based on adaptation coefficients, to determine the cable head end echo,

a speech detector operable to detect whether speech is present on the voice signal received from the telephony port, wherein the adaptation coefficients are held constant when the speech is detected to be present, and wherein the adaptation coefficients are adapted when the speech is not detected to be present, and

a subtractor operable to subtract the cable head end echo from the voice signal received from the telephony port after the adaptation coefficients are held constant.

2. The cable modem of claim 1 further comprising:

a transceiver coupled between the processor and the network port.

3. The cable modem of claim 2, wherein the transceiver comprises:

a media access controller (MAC) coupled to the processor,

a modulator disposed in circuit between the MAC and the network port, and

a demodulator disposed in circuit between the MAC and the network port.

4. The cable modem of claim 1 further comprising:

a voice circuit coupled between the telephony port and the processor.

5. A gateway, comprising:

a network port configured to interface with a cable head end;

a telephony port configured to interface to a telephony device;

a data port configured to interface to a data terminal;

a processor coupled to each of the ports; and

a transceiver disposed in circuit between the processor and the network port, the transceiver being configured;

to transmit and receive a packet of voice signals and a packet of data signals,

to differentiate between a packet of voice signals associated with a voice call and a packet of voice signals associated with a machine call,

to determine whether a packet of voice signals received from the network port is destined for the data port or the telephony port based on whether the packet of voice signals received from the network is associated with the voice call or associated with the machine call, and

to relay a payload of the packet of voice signals received from the network port to one of the data port and telephony port based on such determination,

wherein the transceiver comprises;

an echo canceller operable to cancel a cable head end echo on the voice signals received from the processor, wherein the echo canceller comprises;

a filter operable to adaptively filter the voice signals received from the network port, based on adaptation coefficients, to determine the cable head end echo,

a speech detector operable to detect whether speech is present on the voice signals received from the processor, wherein the adaptation coefficients are held constant when the speech is detected to be present, and wherein the adaptation coefficients are adapted when the speech is not detected to be present, and

a subtractor operable to subtract the cable head end echo from the voice signals received from the processor after the adaptation coefficients are held constant.

6. The gateway of claim 5, wherein the transceiver comprises:

a media access controller (MAC) coupled to the processor,

a modulator disposed in circuit between the MAC and the network port, and

a demodulator disposed in circuit between the MAC and the network port.

7. The gateway of claim 5, further comprising:

a voice circuit coupled between the telephony port and the processor.

8. A method of processing signals, comprising:

exchanging a voice signal, including a voice signal associated with a voice call and a voice signal associated with a machine call, between a cable head end and a telephony device;

exchanging a data signal between the cable head end and a data terminal, the data signal including the voice signal associated with the machine call; and

wherein exchanging the voice signal comprises;

canceling a cable head end echo on a voice signal flowing from the telephony device to the cable head end, the canceling the cable head end echo comprising;

adaptively filtering a received signal from the cable head end based on adaptation coefficients to determine a cable head end echo,

detecting whether speech is present on the voice signal flowing from the telephony device to the cable head end,

holding the adaptation coefficients constant when the speech is detected to be present,

converging the adaptation coefficients when the speech is not detected to be present, and

subtracting the cable head end echo from the voice signal flowing from the telephony device after the adaptation coefficients are held constant.

9. The method of claim 8, further comprising:

demodulating voice signals flowing from the cable head end to the telephony device and the data terminal; and

modulating voice signals flowing from the telephony device and the data terminal to the cable head end.

10. The method of claim 8, wherein the exchanging data signals comprises:

receiving a data signal from the cable head end; and

transmitting the data signal to the data terminal over a local area network.

11. The method of claim 8, wherein the exchanging voice signals comprises:

receiving a first voice signal from the cable head end; and

transmitting the first voice signal to the telephony device over a telephone line.

12. The method of claim 11, wherein the exchanging voice signals comprises:

exchanging a second voice signal between the cable head end and a second telephony device, exchanging the second signal comprising;

receiving the second voice signal from the cable head end; and

transmitting the second voice signal to the second telephony device over a local area network.

13. The method of claim 8, wherein the canceling the cable head end echo comprises:

delaying subtracting the cable head end echo from the voice signal flowing from the telephony device for a time after the detection of the speech.

14. The method of claim 8, wherein the detecting whether the speech is present comprises:

estimating an absolute value of a cable head end signal parameter;

estimating a maximum parameter of the voice signal flowing from the telephony device;

comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal flowing from the telephony device; and

detecting the speech on the voice signal flowing from the telephony device based on the comparison.

15. The method of claim 8, wherein the canceling the cable head end echo comprises:

pre-conditioning the voice signal flowing from the telephony device prior to the detecting whether the speech is present.

16. The method of claim 15, wherein the preconditioning the voice signal flowing from the telephony device comprises:

adaptively filtering the cable head end signal; and

subtracting the adaptively filtered cable head end signal from the voice signal flowing from the telephony device.

17. The method of claim 8, wherein the exchanging voice signal comprises:

synchronizing the voice signal between the cable head end and the telephony device.

18. The method of claim 17, wherein the synchronizing the voice signal comprises:

generating an error signal based on a function of a difference between a cable head end clock and a voice exchange clock; and

fractionally resampling an exchanged voice signal based on a function of the error signal.

19. The method of claim 18, wherein generating the error signal comprises:

driving a first counter with the cable head end clock,

driving a second counter with the voice exchange clock, and

dividing an output of the first counter by an output of the second counter to generate the error signal.

20. The method of claim 19, wherein the synchronizing the voice signal comprises:

fractionally up-sampling the exchanged voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

21. The method of claim 19, wherein the synchronizing the voice signal comprises:

fractionally down-sampling the exchanged voice signal by the error signal when the output of the first counter is less than the output of the second counter.

22. The method of claim 19, wherein the synchronizing voice signal comprises:

filtering the output of the first counter; and

filtering the output of the second counter; and

wherein the dividing comprises dividing a filtered output of the first counter by a filtered output of the second counter.

23. The method of claim 8, further comprising:

determining whether a received voice signal is associated with the voice call or associated with the machine call; and

decimating the received voice signal based on the determining.

24. The method of claim 23, wherein the decimating of the received voice signal is performed using a minimum phase filter if the received voice signal is associated with the voice call.

25. The method of claim 23, wherein the decimating of the received voice signal is performed using a linear phase filter if the received voice signal is associated with the machine call.

26. A cable modem, comprising:

a first network port configured to interface with a cable head end;

a second network port configured to interface with a local area network, the local area network comprising a packet based network, the packet based network being configured to transmit a voice signal packet;

a telephony port configured to interface with a telephony device; and

a processor, coupled to each of the ports, configured to

differentiate a voice signal packet associated with a voice call from a voice signal packet comprising data superimposed on a voiceband signal,

determine whether a voice signal packet received from the first network port is destined for the second network port or the telephony port based on whether the voice signal packet received from the first network port is associated with the voice call or the voice signal packet received from the first network port comprises the data superimposed on the voiceband signal, and

send the voice signal packet received from the first network port to one of the second network port and telephony port based on such determination,

wherein the processor comprises;

an echo canceller operable to cancel a cable head end echo on a voice signal packet received from the telephony port, wherein the echo canceller comprises;

a filter operable to adaptively filter the voice signal packet received from the first network port, based on adaptation coefficients, to determine the cable head end echo,

a speech detector operable to detect whether speech is present on the voice signal packet received from the telephony port, wherein the adaptation coefficients are held constant when the speech is detected to be present, and wherein the adaptation coefficients are adapted when the speech is not detected to be present, and

a subtractor operable to subtract the cable head end echo from the voice signal packet received from the telephony port after the adaptation coefficients are held constant.

27. The cable modem of claim 26, further comprising:

a modulator configured to modulate the voice signal packet received from the first network port at a frequency above a frequency of the voiceband signal.

28. The cable modem of claim 26, wherein the packet based network comprises:

a twisted pair telephone line.

29. The cable modem of claim 26, wherein the packet based network is configured to operate in accordance with a protocol for home communications over a twisted pair telephone line.

30. The cable modem of claim 26, wherein the packet based network comprises:

an Ethernet line.

31. The cable modem of claim 26, further comprising:

a transceiver coupled between the processor and the first network port.

32. The cable modem of claim 31, wherein the transceiver comprises:

a media access controller (MAC) coupled to the processor,

a modulator disposed in circuit between the MAC and the first network port, and

a demodulator disposed in circuit between the MAC and the first network port.

33. The cable modem of claim 26, further comprising:

a voice circuit coupled to the second network port and to the processor.

34. The cable modem of claim 26, further comprising:

a voice synchronizer configured to synchronize a voice signal communicated between the cable head end and the cable modem by generating an error signal based on a function of a difference between a cable head end clock and a local clock.

35. The cable modem of claim 34, further comprising:

a time stamp register,

wherein the cable modem is configured to synchronize telephony devices coupled to the local area network by periodically writing a value of the en-or signal into the time stamp register and transporting the value of the en-or signal over the second network port.

36. A gateway, comprising:

a first network port configured to interface with a cable head end;

a second network port configured to interface to a local area network;

a processor coupled to the first network port and to the second network port;

a transceiver, disposed in a circuit between the processor and the first network port, configured to transmit and receive packets of voice signals associated with voice calls and packets of data signals, the packets of data signals including voice signals associated with machine calls;

an encryption circuit coupled to the transceiver and to the processor; and

a voice circuit coupled to the second network port and to the processor,

wherein the processor is configured to

discriminate between the packets of voice signals associated with voice calls and the packets of data signals,

determine whether a received packet is destined for the first network port or the second network port based on whether the received packet is a packet of voice signals associated with a voice call or a packet of data signals, and

send the received packet to one of the first network port and the second network port based on the determination,

wherein the processor comprises;

an echo canceller operable to cancel a cable head end echo on a transmitted voice packet, wherein the echo canceller comprises;

a filter operable to adaptively filter the received packet, based on adaptation coefficients, to determine the cable head end echo,

a speech detector operable to detect whether speech is present on the transmitted voice packet, wherein the adaptation coefficients are held constant when the speech is detected to be present, and wherein the adaptation coefficients are adapted when the speech is not detected to be present, and

a subtractor operable to subtract the cable head end echo from the voice transmitted voice packet after the adaptation coefficients are held constant.

37. The gateway of claim 36, wherein the local area network comprises:

a packet based network.

38. The gateway of claim 37, wherein the packet based network comprises:

a twisted pair telephone line.

39. The gateway of claim 37, wherein the packet based network is configured to operate in accordance with a protocol for home communications over a twisted pair telephone line.

40. The gateway of claim 37, wherein the packet based network comprises:

an Ethernet line.

41. The gateway of claim 36, wherein the transceiver comprises:

a media access controller (MAC) coupled to the processor,

a modulator disposed in circuit between the MAC and the first network port, and

a demodulator disposed in circuit between the MAC and the first network port.

42. A method of processing signals, comprising:

exchanging voice signals between a cable head end and a local area network, comprising;

exchanging voice signals associated with voice calls between the cable head end and the local area network, and

exchanging data signals between the cable head end and the local area network, the data signals including voice signals associated with machine calls;

classifying a received voice signal received from the local area network as a data signal or a voice signal associated with a voice call; and

decimating the received voice signal in accordance with the classifying;

wherein the exchanging voice signals comprises;

synchronizing voice signals exchanged between the cable head end and the local area network, the synchronizing comprising;

generating an error signal based on a function of a difference between a cable head end clock and a voice exchange clock, and

fractionally resampling an exchanged voice signal based on a function of the error signal.

43. The method of claim 42, wherein the local area network comprises:

a packet based network.

44. The method of claim 43, wherein the packet based network comprises:

a twisted pair telephone line.

45. The method of claim 43, wherein the packet based network is configured to operate in accordance with a protocol for home communications over a twisted pair telephone line.

46. The method of claim 43, wherein the packet based network comprises:

an Ethernet line.

47. The method of claim 43, wherein the packet based network is configured to transmit a packet including a voice signal comprising data superimposed on a voiceband signal.

48. The method of claim 43, wherein the packet comprises:

data modulated at a frequency above a frequency of the voiceband signal.

49. The method of claim 42, further comprising:

demodulating a first data signal flowing from the cable head end to the local area network; and

modulating a second data signal flowing from the local area network to the cable head end.

50. The method of claim 42, wherein the exchanging the voice signals comprises:

canceling a cable head end echo on a voice signal flowing from the local area network to the cable head end.

51. The method of claim 50, wherein the canceling comprises:

adaptively filtering a received signal from the cable head end based on adaptation coefficients to determine a cable head end echo;

detecting whether speech is present on the voice signal flowing from the local area network to the cable head end;

holding the adaptation coefficients constant when the speech is present; and

subtracting the cable head end echo from the voice signal flowing from the local area network after the adaptation coefficients are held constant.

52. The method of claim 51, wherein the canceling comprises:

delaying the subtracting the cable head end echo from the voice signal flowing from the local area network for a time after the detection of speech.

53. The method of claim 51, wherein the detecting whether speech is present comprises:

estimating an absolute value of a cable head end signal parameter;

estimating a maximum parameter of the voice signal flowing from the local area network;

comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal; and

detecting speech on the voice signal flowing from the local area network based on a function of the comparison.

54. The method of claim 51, wherein the canceling comprises:

pre-conditioning the voice signal flowing from the local area network prior to the detecting whether the speech is present.

55. The method of claim 52, wherein the preconditioning the voice signal comprises:

adaptively filtering the received signal from the cable head end and subtracting the adaptively filtered received signal from the voice signal flowing from the local area network.

56. The method of claim 42, wherein the generating the error signal comprises:

driving a first counter with the cable head end clock;

driving a second counter with the voice exchange clock; and

dividing an output of the first counter by an output of the second counter to generate the error signal.

57. The method of claim 56, wherein the synchronizing voice signals comprises:

fractionally up-sampling the exchanged voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

58. The method of claim 56, wherein the synchronizing voice signals comprises:

fractionally down-sampling the exchanged voice signal by the error signal when the output of the first counter is less than the output of the second counter.

59. The method of claim 56, wherein the synchronizing voice signals comprises:

filtering the output of the first counter; and

filtering the output of the second counter,

wherein the dividing comprises dividing a filtered output of the first counter by a filtered output of the second counter.

60. The method of claim 42, further comprising:

periodically communicating a value of the error signal over the local area network.

61. The method of claim 42, further comprising:

communicating a timestamp report to a device coupled to the local area network; and

generating an offset value based on an offset between a cable modem clock and a local area network clock.

62. The method of claim 61, further comprising:

communicating a grant receive value to the device coupled to the local area network; and

communicating packets from the device to the cable modem in accordance with the grant receive value and the offset value, wherein the packets arrive at the cable modem prior to a subsequent upstream grant.

63. The method of claim 62, further comprising:

generating a packet assembly start time based on the offset value, the grant receive value, a packet assembly overhead, a queuing latency and a transmission time.

64. The method of claim 42, wherein the decimating comprises:

decimating a signal classified as a voice signal associated with a voice call with a minimum phase filter.

65. The method of claim 42, wherein the decimating comprises:

decimating a signal classified as a data signal with a linear phase filter.

66. A gateway, comprising:

a processor operable to exchange voice signals, including voice signals associated with voice calls, between a cable head end and a telephony device, the processor comprising;

an echo canceller operable to cancel a cable head end echo on a voice signal flowing from the telephony device to the cable head end, comprising;

a filter operable to adaptively filter a received signal from the cable head end based on adaptation coefficients to determine the cable head end echo,

a speech detector operable to detect whether speech is present on the voice signal flowing from the telephony device, wherein the adaptation coefficients are held constant when the speech is detected to be present, and wherein the adaptation coefficients are converged when the speech is not detected to be present, and

a subtractor operable to subtract the cable head end echo from the voice signal flowing from the telephony device after the adaptation coefficients are held constant; and

at least one circuit operable to exchange data signals between the cable head end and a data terminal, the data signals including voice signals associated with machine calls.

67. The gateway of claim 66, further comprising:

a demodulator operable to demodulate voice signal signals flowing from the cable head end to the telephony device and the data terminal; and

a modulator operable to modulate voice signals flowing from the telephony device and the data terminal to the cable head end.

68. The gateway of claim 66, wherein the at least one circuit comprises:

a receiver operable to receive a data signal from the cable head end; and

a transmitter operable to transmit the data signal to the data terminal over a local area network.

69. The gateway of claim 66, wherein the at least one circuit comprises:

a first receiver operable to receive a first voice signal from the cable head end; and

a first transmitter operable to transmit the first voice signal to the telephony device over a telephone line.

70. The gateway of claim 69, wherein the at least one circuit comprises:

a second receiver operable to receive the second voice signal; and

a second transmitter operable to transmit the second voice signal to the second telephony device over a local area network.

71. The gateway of claim 66, wherein the echo canceller comprises:

a delay operable to delay the cable head end echo, prior to being subtracted from the voice signal flowing from the telephony device, based on the detection of speech.

72. The gateway of claim 66, wherein the speech detector comprises:

a first estimator operable to estimate an absolute value of a cable head end signal parameter;

a second estimator operable to estimate a maximum parameter of the voice signal flowing from the telephony device,

a comparator operable to compare the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal flowing from the telephony device; and

a detector operable to detect the speech on the voice signal flowing from the telephony device based on the comparison.

73. The gateway of claim 66, wherein the echo canceller comprises:

a conditioning circuit operable to pre-condition the voice signal flowing from the telephony device prior to detecting whether the speech is present.

74. The gateway of claim 73, wherein the echo canceller comprises:

a second filter operable to adaptively filter the cable head end signal; and

a second subtractor operable to subtract the adaptively filtered cable head end signal from the voice signal flowing from the telephony device.

75. The gateway of claim 66, wherein the at least one circuit comprises:

a synchronizer operable to synchronize voice signals between the cable head end and the telephony device.

76. The gateway of claim 75, wherein the synchronizer comprises:

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a voice exchange clock; and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.

77. The gateway of claim 76, wherein the generator comprises:

a first counter driven by the cable head end clock;

a second counter driven by the voice exchange clock; and

a divider operable to divide an output of the first counter by an output of the second counter to generate the error signal.

78. The gateway of claim 77, wherein the synchronizer comprises:

an up-converter operable to fractionally up-sample the exchanged voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

79. The gateway of claim 77, wherein the synchronizer comprises:

a down-converter operable to fractionally down-sample the exchanged voice signal by the error signal when the output of the first counter is less than the output of the second counter.

80. The gateway of claim 77, wherein the synchronizer comprises:

a first counter filter operable to filter the output of the first counter; and

a second counter filter operable to filter the output of the second counter,

wherein the divider is configured to divide the filtered output of the first counter by the filtered output of the second counter.

81. A gateway, comprising:

a processor operable to exchange voice signals between a cable head end and a local area network, comprising

at least one circuit operable to exchange voice signals associated with voice calls between the cable head end and the local area network and operable to exchange data signals between the cable head end and the local area network, wherein the data signals include voice signals associated with machine calls;

a classifier operable to classify a received voice signal received from the local area network as a data signal or a voice signal associated with a voice call; and

a decimator operable to decimate the received voice signal in accordance with classifying,

wherein the at least one circuit comprises;

a synchronizer operable to synchronize voice signals exchanged between the cable head end and the local area network, the synchronizer comprising;

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a voice exchange clock, and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.

82. The gateway of claim 81, wherein the local area network comprises:

a packet based network.

83. The gateway of claim 82, wherein the packet based network comprises:

a twisted pair telephone line.

84. The gateway of claim 82, wherein the packet based network is configured to operate in accordance with a protocol for home communications over a twisted pair telephone line.

85. The gateway of claim 82, wherein the packet based network comprises:

an Ethernet line.

86. The gateway of claim 81, further comprising:

a demodulator operable to demodulate a first data signal flowing from the cable head end to the local area network; and

a modulator operable to modulate a second voice signal flowing from the local area network to the cable head end.

87. The gateway of claim 81, wherein the at least one circuit comprises:

a receiver operable to receive data signals from a telephony device via the local area network; and

a transmitter operable to transmit data signals to the telephony device via the local area network.

88. The gateway of claim 81, wherein the at least one circuit operable to comprises:

a first receiver operable to receive a first voice signal from the cable head end; and

a first transmitter operable to transmit the first voice signal to the telephony device via the telephone line.

89. The gateway of claim 88, wherein the at least one circuit comprises:

a second receiver operable to receive the second voice signal from the cable head end; and

a second transmitter operable to transmit the second voice signal to the second telephony device over the local area network.

90. The gateway of claim 81, wherein the at least one circuit comprises:

an echo canceller operable to cancel a cable head end echo on a voice signal flowing from the local area network to the cable head end.

91. The gateway of claim 90, wherein the echo canceller comprises:

a filter operable to adaptively filter a received signal from the cable head end based on adaptation coefficients to determine a cable head end echo;

a speech detector operable to detect whether speech is present on the voice signal flowing from the local area network to the cable head end, wherein the adaptation coefficients are held constant when the speech is present; and

a subtractor operable to subtract the cable head end echo from the voice signal flowing from the local area network after the adaptation coefficients are held constant.

92. The gateway of claim 91, wherein the echo canceller comprises:

a delay operable to delay the cable head end echo, prior to being subtracted from the voice signal flowing from the telephony device, based on the detection of speech.

93. The gateway of claim 91, wherein the speech detector comprises:

a first estimator operable to estimate an absolute value of a cable head end signal parameter;

a second estimator operable to estimate a maximum parameter of the voice signal flowing from the telephony device,

a comparator operable to compare the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal flowing from the telephony device; and

a detector operable to detect the speech on the voice signal flowing from the telephony device based on a function of the comparison.

94. The gateway of claim 91, wherein the echo canceller comprises:

a conditioning circuit operable to pre-condition the voice signal flowing from the telephony device prior to detecting whether the speech is present.

95. The gateway of claim 94, wherein the echo canceller comprises:

a second filter operable to adaptively filter the cable head end signal; and

a second subtractor operable to subtract the adaptively filtered cable head end signal from the voice signal flowing from the telephony device.

96. The gateway of claim 81, wherein the generator comprises:

a first counter driven by the cable head end clock;

a second counter driven by the voice exchange clock; and

a divider operable to divide an output of the first counter by an output of the second counter to generate the error signal.

97. The gateway of claim 96, wherein the synchronizer comprises:

an up-converter operable to fractionally up-sample the exchanged voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

98. The gateway of claim 96, wherein the synchronizer comprises:

a down-converter operable to fractionally down-sample the exchanged voice signal by the error signal when the output of the first counter is less than the output of the second counter.

99. The gateway of claim 96, wherein the synchronizer comprises:

a first counter filter operable to filter the output of the first counter; and

a second counter filter operable to filter the output of the second counter,

wherein the divider is configured to divide the filtered output of the first counter by the filtered output of the second counter.

100. A cable modem, comprising:

a network port configured to interface with a cable head end;

a telephony port configured to interface with a telephony device;

a data port configured to interface with a data terminal;

a processor, coupled to each of the ports, configured to;

differentiate between a voice signal associated with a voice call and a voice signal associated with a machine call,

determine whether a voice signal received from the network port is destined for the data port or the telephony port based on whether the voice signal received from the network port is associated with the voice call or the machine call, and

send the voice signal received from the network port to one of the data port and the telephony port based on such determination;

a decimator operable to decimate the received voice signal in accordance with the differentiation by the processor; and

a synchronizer operable to synchronize voice signals exchanged between the cable head end and the telephony device, the synchronizer comprising;

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a voice exchange clock, and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.

101. A gateway, comprising:

a network port configured to interface with a cable head end;

a telephony port configured to interface to a telephony device;

a data port configured to interface to a data terminal;

a processor coupled to each of the ports;

a transceiver disposed in circuit between the processor and the network port, the transceiver being configured;

to transmit and receive a packet of voice signals and a packet of data signals,

to differentiate between a packet of voice signals associated with a voice call and a packet of voice signals associated with a machine call,

to determine whether a packet of voice signals received from the network port is destined for the data port or the telephony port based on whether the packet of voice signals received from the network is associated with the voice call or associated with the machine call, and

to relay a payload of the packet of voice signals received from the network port to one of the data port and telephony port based on such determination;

a decimator operable to decimate the received packet of voice signals in accordance with the differentiation by the transceiver; and

a synchronizer operable to synchronize voice signals exchanged between the cable head end and the telephony device, the synchronizer comprising;

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a voice exchange clock, and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.

102. A cable modem, comprising:

a first network port configured to interface with a cable head end;

a second network port configured to interface with a local area network, the local area network comprising a packet based network, the packet based network being configured to transmit a voice signal packet;

a telephony port configured to interface with a telephony device;

a processor, coupled to each of the ports, configured to

differentiate a voice signal packet associated with a voice call from a voice signal packet comprising data superimposed on a voiceband signal,

determine whether a voice signal packet received from the first network port is destined for the second network port or the telephony port based on whether the voice signal packet received from the first network port is associated with the voice call or the voice signal packet received from the first network port comprises the data superimposed on the voiceband signal, and

send the voice signal packet received from the first network port to one of the second network port and telephony port based on such determination;

a decimator operable to decimate the received voice signal packet in accordance with the differentiation by the processor; and

a synchronizer operable to synchronize voice signals exchanged between the cable head end and the telephony device, the synchronizer comprising;

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a voice exchange clock, and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.

103. A gateway, comprising:

a first network port configured to interface with a cable head end;

a second network port configured to interface to a local area network;

a processor coupled to the first network port and to the second network port;

a transceiver, disposed in a circuit between the processor and the first network port, configured to transmit and receive packets of voice signals associated with voice calls and packets of data signals, the packets of data signals including voice signals associated with machine calls;

an encryption circuit coupled to the transceiver and to the processor; and

a voice circuit coupled to the second network port and to the processor,

wherein the processor is configured to

discriminate between the packets of voice signals associated with voice calls and the packets of data signals,

determine whether a received packet is destined for the first network port or the second network port based on whether the received packet is a packet of voice signals associated with a voice call or a packet of data signals, and

send the received packet to one of the first network port and the second network port based on the determination;

a decimator operable to decimate the received packet of voice signals in accordance with the differentiation by the processor; and

a synchronizer operable to synchronize voice signals exchanged between the cable head end and the local area network, the synchronizer comprising;

a generator operable to generate an error signal based on a function of a difference between a cable head end clock and a local area network clock, and

a sample rate converter operable to fractionally resample an exchanged voice signal based on a function of the error signal.