Method of transporting compressed speech in packet mode in the core network of public land mobile network infrastructures

1 . A method of transporting compressed speech in packet mode in the core network of public land mobile network infrastructures over a core network segment including a pair of transcoders equipped to operate in a tandem-free operation mode enabling transportation of compressed speech over said segment, said transcoders being adapted to format the compressed speech in a first format including compressed speech data and uncompressed speech data, in which method, for optimum transport in packet mode over the whole or a portion of said segment, said first format is changed to a second format including only compressed speech data.

2 . A method according to claim 1 , wherein said first format corresponds to coded samples including “x” compressed speech bits and “n-x” uncompressed speech bits, where “n” is the total number of bits in a coded sample, and said second format corresponds to coded samples including only “x” compressed speech bits.

3 . A method according to claim 1 , wherein a node of said segment receiving speech data in said first format and detecting that the next node is equipped to process speech data in said second format effects a change from said first format to said second format for sending to said next node.

4 . A method according to claim 1 , wherein a node of said segment receiving speech data in said second format and detecting that the next node is equipped to process speech data in said second format forwards said data in said second format to said next node.

5 . A method according to claim 1 , wherein a node of said segment receiving speech data in said second format and detecting that the next node is not equipped to process speech data in said second format effects a change from said second format to a third format including compressed speech data and meaningless data for sending to said next node.

6 . A method according to claim 5 , wherein a node of said segment receiving speech data in said third format and detecting that the next node is equipped to process speech data in said second format effects a change from said third format to said second format for sending to said next node.

7 . A method according to claim 5 , wherein said third format corresponds to coded samples comprising “x” compressed speech bits and “n-x” meaningless bits, where “n” is the total number of bits in a coded sample.

8 . A method according to claim 2 , where “n” is equal to 8 and the value of “x” is from 1 to 7.

9 . A method according to claim 7 , where “n” is equal to 8 and the value of “x” is from 1 to 7.

10 . A method according to claim 1 , wherein a node of said segment detects that received speech data is in said first format by detecting if the tandem-free operation mode has been activated.

11 . A method according to claim 3 , wherein a node of said segment informs at least one subsequent node of said segment if it effects a change from said first format to said second format for sending to said next node.

12 . A method according to claim 11 , wherein speech data blocks are encapsulated in a framing protocol for transfer between core network nodes and a node informs at least one subsequent node if it effects a format change by means of a format indication for said data blocks sent in accordance with said framing protocol.

13 . A method according to claim 11 , wherein said first format corresponds to coded samples including “x” compressed speech bits and “n-x” uncompressed speech bits, where “n” is the total number of bits in a coded sample, and said second format corresponds to coded samples including only “x” compressed speech bits, and wherein said framing protocol includes an initialization procedure for fixing the size of the data blocks that can be exchanged in accordance with that protocol and the possible data block sizes include the various possible values of “x”.

14 . A method according to claim 3 , wherein a node of said segment is configured to recognize if the next node to which it sends speech data is equipped to process speech data in said second format.

15 . A method according to claim 3 , wherein a node of said segment detects if the next node to which it sends speech data is equipped to process speech in said second format by means of the signaling protocol used for each call.

16 . A core network node for public land mobile network infrastructures, comprising means for implementing a method according to claim 1.