Change of codec during an active call

• US 7,307,980 B1
• Filed: 07/02/1999
• Issued: 12/11/2007
• Est. Priority Date: 07/02/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shah, Nirat Bhupesh
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): LY, ANH VU H
• Application Number:
  US09/346,884
• Time in Patent Office: 3,084 Days
• Field of Search: 370/352, 370/353, 370/356, 370/493, 379/93.08, 379/93.09, 379/100.12, 379/100.17, 379/220.01
• US Class Current: 370/352
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Abstract

A router device is disclosed for use in a communication system having at least two telephone devices in communications with each other for transferring voice information therebetween through a packet switching network. The router device is coupled between one of the telephone devices and the packet switching network for performing one of a plurality of types of compression/decompression (codec) operation on information being transferred between the telephone devices. The router device includes a Digital Signal Processor (DSP) module responsive to an analog telephone signal for carrying a telephone conversation generated from one of the telephone devices and operative to convert the analog telephone signal to a digital telephone signal. The DSP packetizes the digital telephone signal for transmission to a remotely-located router device and switches from using a first type of codec to using a second type of codec upon detection of degradation in the quality of the voice information while a conversation is taking place between the two telephone device yet avoiding substantial disturbance to users of the telephone devices.

Claims

1. A device comprising:

a Digital Signal Processor (DSP) module to receive an analog telephone signal to convert the analog telephone signal to a digital telephone signal and further to packetize the digital telephone signal for transmission to a remotely-located device;

the device and the remotely-located device to negotiate a first type of codec by each sending to the other a list of one or more types of codecs that each supports and each deciding to use a mutually supported codec through the use of a predetermined protocol; and

during communications between the remotely-located device and the DSP module, the DSP module to renegotiate a second type of codec, wherein the renegotiation is triggered upon detection of degradation in voice quality by the remotely-located device, and

the DSP module to dynamically switch to the second codec only if the device determines that the second codec is available therein,

wherein, the type of codec being utilized repeatedly, mutually, renegotiated to dynamically change compression techniques and switching between the codecs is performed during a call.

2. A device as recited in claim 1 wherein switching between the codecs is initiated by a user of one of the telephone devices.

3. A device as recited in claim 2 wherein a predetermined code is assigned to correspond to each codec wherein the user specifies the type of codec to be switched to by entering the predetermined code corresponding to a desired codec.

4. A device as recited in claim 3 wherein the predetermined code is programmably-alterable.

5. A device as recited in claim 1 further comprising the device to switch from a codec resulting in the use of larger packet sizes to a codec resulting in smaller packet sizes in response to detecting a lower available bandwidth on a packet switching network.

6. A device as recited in claim 5 wherein the device is configured to automatically detect the lower bandwidth.

7. A device as recited in claim 1 wherein upon detecting higher bandwidth available on packet switching network, the device to switch from a codec resulting in the use of smaller packet sizes to a codec resulting in higher packet sizes.

8. A device as recited in claim 7 wherein the device to automatically detect the higher bandwidth.

9. A device as recited in claim 1 wherein the remotely-located device to detect the degradation in the quality of voice information.

10. A device as recited in claim 1 wherein the degradation in the quality of voice information is due to loss of one or more packets.

11. A device as recited in claim 10 wherein a threshold defines the number of lost packets that are tolerated and the device to trigger a decision to switch to the second type of codec.

12. A device as recited in claim 11 wherein a plurality of packets form a message and each packet includes a sequence number indicative of the position of the packet with respect to other packets in the same message, the sequence numbers of the same message being in sequential order wherein a loss of packets is detected when one or more sequence numbers are missing from the received packets of the same message.

13. A device as recited in claim 1 wherein the degradation in the quality of voice information is due to an intolerable delay associated with the time for a packet to travel between the device and the remotely located device.

14. A device as recited in claim 1 wherein the codec negotiation is performed pursuant to the H.245 protocol.

15. A device as recited in claim 1 wherein the first type of codec includes a compression/decompression algorithm defined by any one of the standards:

G.711, G726, G729 or G723.1 and the second type of codec utilizes a compression/decompression algorithm defined by any one of the standards;

G.711, G726, G729 or G723.1.

16. A method comprising:

receiving at a first router an analog telephone signal through a telephone connection from a first telephone device;

converting the analog telephone signal to a digital telephone signal;

separating information carried on the digital telephone signal into packets of information;

initially, mutually, negotiating with a second router a first type of codec for communication with a second telephone device, by each sending to the other one or more types of codecs that each supports and each deciding to use a mutually supported codec through the use of a predetermined protocol;

using a first type of codec for transferring the packets of information between the first and second router through a packet switching network;

during communication between the telephone devices, the first and second router renegotiating the use of a second type of codec, wherein the renegotiation is triggered upon detection of degradation in voice quality by the second router;

switching to using the second type of codec only if the first router determines that the second codec is available therein; and

during communication between the telephone devices, upon further detection of degradation in voice quality by the second router, repeatedly renegotiating to dynamically change compression.