Method for downloading and selecting an encoding/decoding algorithm to a mobile telephone

1. A method of operating a mobile telephone that is taken up in a data transmission network, which method involves at least one existing encoding and decoding algorithm for converting analog speech data into digital data and vice versa, the method comprising the steps of:

establishing a data transmission link between the mobile telephone and the data transmission network;

receiving, by the mobile telephone, a new encoding and decoding algorithm from the data transmission network;

storing the received new encoding and decoding algorithm in a non-volatile memory located in the mobile telephone;

displaying and enabling selection, by the user, between the existing or the new encoding and decoding algorithm for data conversion; and

switching between the exiting and the new encoding and decoding algorithms, dependent upon the algorithm selected.

2. The method of claim 1 , wherein the new encoding and decoding algorithm is used as an alternative for the existing encoding and decoding algorithm, and that each time either algorithm can be selected by the user.

3. The method of claim 1 , wherein to establish the data transmission link for the transmission of the new encoding and decoding algorithm, the network transmits an SMS message to the mobile telephone or makes a direct call to the mobile telephone in order to initiate a call from the mobile telephone to the network.

4. The method of claim 1 , wherein the data transmission link is in conformity with the GSM standard, notably the protocols DCS 1800 or PCS 1900.

5. The method of claim 1 , wherein at the end of the data transmission, or after a part of the data transmission, a test sum is transmitted so as to be compared with a test sum calculated by the mobile telephone from the transmitted data, the data transmission being terminated in the case of identical test stuns whereas it is repeated in the case of different test sums.

6. A mobile telephone including at least one existing encoding and decoding algorithm for converting analog speech data into digital data and vice versa, comprising:

a non-volatile memory;

means for receiving at least one new encoding and decoding algorithm via a data transmission link established between the mobile telephone and the network;

means for storing said new encoding and decoding algorithm in the non-volatile memory;

means for displaying and enabling the user to select either the existing or the new encoding and decoding algorithm for data conversion; and

means for switching between the exiting and the new encoding and decoding algorithms, depended upon the algorithm selected.

7. The mobile telephone of claim 6 , wherein the non-volatile memory is constructed as an EEPROM or Flash PROM.