Method and apparatus for suppressing echo cancelling in a packet switched network

• US 7,583,621 B2
• Filed: 10/05/2004
• Issued: 09/01/2009
• Est. Priority Date: 10/05/2004
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Page, William B., Wang, Yan, Qi, David Cheng-Song, Wade, Timothy G.
• Primary Examiner(s): Jamal; Alexander
• Application Number:
  US10/958,751
• Publication Number:
  US 20060072484A1
• Time in Patent Office: 1,792 Days
• Field of Search: 370/286
• US Class Current: 370/286
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers

Abstract

A method, or corresponding apparatus, assumes a call is a Voice Band Data (VBD) call. The method disables a local echo canceller and transmits a tone that disables distal echo canceller(s) along a communications path across which the call is communicated. After disabling the echo cancellers, the echo cancellers are allowed to operate in a typical manner, such as according to ITU standards, after the call is established, including remaining disabled if the call is a Voice Band Data call and being automatically enabled if the call is or becomes a voice call. The method or apparatus is particularly useful in networks having Point of Service (POS) devices that have modems that do not send out a 2100 Hz tone to disable echo cancelling in the communications path. In one embodiment, the method or corresponding apparatus is deployed in a gateway.

Claims

1. A method of suppressing echo cancelling in a packet switched communications network, the method comprising:

disabling a local echo canceller in a local network node, through which a call supported by the local network node and a distal network node is established, via the packet switched communications network, in a presence of a request to establish either a voice band data call or voice call; and

after a connection of either the voice band data call or the voice call is established, transmitting a tone, via a local gateway, that disables a distal echo canceller in the distal network node.

2. The method according to claim 1 further including allowing the echo cancellers to operate in a typical manner after the call is established, including remaining disabled if the call is a voice band data call and automatically enabling if the call is or becomes a voice call.

3. The method according to claim 1 wherein the tone is a 2100 Hz tone with phase reversal.

4. The method according to claim 1 wherein the tone is adjustable in length between 100 msec and 1000 msec.

5. The method according to claim 1 further including selectively enabling or disabling transmitting the tone.

6. The method according to claim 1 wherein disabling the local echo canceller occurs before, simultaneously with, or after transmitting the tone.

7. The method according to claim 1 wherein transmitting the tone includes transmitting data representing the tone.

8. The method according to claim 1 used in connection with a communications path associated with a Point of Service (POS) device unequipped to disable echo cancelling.

9. The method according to claim 1 wherein at least one of the network nodes is a gateway.

10. An apparatus for suppressing echo cancelling in a packet switched communications network, the apparatus comprising:

a local echo canceller in a local network node through which a call supported by the local network node and a distal network node is established;

a local network interface adapted to communicate with a distal network interface in the distal network node via the packet switched communications network, the distal network node including a distal echo canceller; and

a processor in communication with the local echo canceller and local network interface that;

disables the local echo canceller, in a presence of a request to establish either a voice band data call or voice call; and

after a connection of either the voice band data call or the voice call is established, transmits a tone via the local interface that disables the distal echo canceller.

11. The apparatus according to claim 10 wherein the processor further allows the echo cancellers to operate in a typical manner after the call is established, including remaining disabled if the call is a voice band data call and being automatically enabled if the call is or becomes a voice call.

12. The apparatus according to claim 10 wherein the tone is a 2100 Hz tone with phase reversal.

13. The apparatus according to claim 10 wherein the tone is adjustable in length between 100 msec and 1000 msec.

14. The apparatus according to claim 10 wherein the processor further selectively enables or disables transmitting of the tone.

15. The apparatus according to claim 10 wherein the processor disables the local echo canceller before, simultaneously with, or after it transmits the tone.

16. The apparatus according to claim 10 wherein the processor transmits the tone in the form of data representing the tone.

17. The apparatus according to claim 10 used in connection with a communications path associated with a Point of Service (POS) device unequipped to disable echo cancelling.

18. The apparatus according to claim 10 wherein at least one of the network nodes is a gateway.

19. A computer program product having a computer readable medium including computer program logic recorded thereon that, when executed on a computer processor, causes the processor to:

disable a local echo canceller in a local network node through which a call supported by the local network node and a distal network node is established via a packet switched communications network, in a presence of a request to establish either a voice band data call or voice call; and

after a connection of either the voice band data call or the voice call is established, transmit a tone, via a local gateway, that disables a distal echo canceller in the distal network node.

20. The computer program product according to claim 19 further including logic that causes the processor to allow the echo cancellers to operate in a typical manner after the call is established, including remain disabled if the call is a voice band data call and automatically enable if the call is or becomes a voice call.

21. The computer program product according to claim 19 wherein the tone is a 2100 Hz tone with phase reversal.

22. The computer program product according to claim 19 wherein the tone is adjustable in length between 100 msec and 1000 msec.

23. The computer program product according to claim 19 further including logic causing the processor to selectively enable or disable transmitting the tone.

24. The computer program product according to claim 19 wherein the logic that causes the processor to disable the local echo canceller causes the disabling to occur before, simultaneously with, or after causing the processor to transmit the tone.

25. The computer program product according to claim 19 wherein the logic that causes the processor to transmit the tone include instructions that cause the processor to transmit data representing the tone.

26. The computer program product according to claim 19 used in connection with a communications path associated with a Point of Service (POS) device unequipped to disable echo cancelling.

27. The computer program product according to claim 19 wherein at least one of the network nodes is a gateway.

28. An apparatus for suppressing echo cancelling in a packet switched communications network, the apparatus comprising:

means for disabling a local echo canceller in a local network node through which a call supported by the local network node and a distal network node is established via the packet switched communications network, in a presence of a request to establish either a voice band data call or voice call; and

means for transmitting a tone, via a local gateway, that disables a distal echo canceller in the distal network node after a connection of either the voice band data call or the voice call is established.