Method and system for establishing a connection in a telecommunication network having different protocols

1. A method, comprising:

establishing a connection in a telecommunication network comprising different protocols, and an interworking function for adapting the different protocol features used for a connection between a calling terminal and the interworking function, and the interworking function and the called terminal;

receiving at the interworking function from a calling terminal a request to establish a connection of a first type (multimedia connection) using first protocol features;

performing a setup processing according to the first protocol features used for the first type of connection between the interworking function and the called terminal;

determining a second type of connection;

checking the result of said setup processing so as to indicate whether or not the setup processing according to the first protocol features has been successful; and, when said checking indicates that said setup processing was not successful,

establishing said second type of connection between the interworking function and the called terminal and

changing the connection between the calling terminal and the interworking function to the second type of connection.

2. A method according to claim 1 , wherein said determining comprises a monitoring operation performed in a network element arranged between the calling terminal and said called terminal.

3. A method according to claim 2 , wherein a connection fallback from said first type of connection to said second type of connection is performed in said network element.

4. A method according to claim 2 , wherein at least one type of connection supported by said called terminal is determined as said second type of connection in said network element by monitoring a signaling for call establishment, and wherein the call is re-established based on the determination result.

5. A method according to claim 4 , wherein the determination result is signaled to said calling terminal which then performs the call re-establishment operation.

6. A method according to claim 1 , wherein said first type of connection is a multimedia connection.

7. A method according to claim 1 , wherein said second type of connection is a speech connection.

8. A method according to claim 1 , further comprising establishing said first type of connection, when said result of said checking indicates that said handshake processing was successful.

9. A method according to claim 1 , wherein said first type of connection is a video connection.

10. A method according to claim 1 , wherein said handshake processing is an interworking processing.

11. A method according to claim 1 , wherein said first type of connection is a connection between a mobile terminal and a network terminal of a fixed network.

12. A method according to 1 , wherein said second type of connection is determined on the basis of said handshake processing.

13. A method according to claim 1 , wherein said second type of connection is determined by performing another handshake processing with said called terminal.

14. A method according to claim 1 , wherein said second type of connection is determined on the basis of the calling number of said called terminal.

15. A method according claim 1 , wherein said second type of connection is determined on the basis of a predetermined priority order.

16. A method according to claim 1 , wherein said first type of connection is compliant with the ITU-T Recommendation H.324.

17. A method according to claim 1 , wherein said second type of connection is established by performing a channel mode modification and changing switching.

18. A method according to claim 1 , further comprising establishing a HSCSD call to said called terminal.

19. A system according to claim 1 , wherein said interworking function is configured to check said first type of connection.

20. A system for establishing a connection in a telecommunication network comprising different protocols, the system comprising:

a negotiating module, implemented as an interworking function, configured to adapt the different protocol features used for a connection between a calling terminal and the interworking function and the interworking function and a called terminal, said negotiating module being configured to, when receiving at the interworking function from a calling terminal a request to establish a connection of a first type using first protocol features, perform a setup processing according to the first protocol features used for the first type of connection between the interworking function and the called terminal;

a determining unit configured to determine a second type of connection;

a checking unit configured to check a result of said setup processing so as to indicate whether or not the setup processing according to the first protocol features has been successful; and

a connection control unit configured to establish said second type of connection between the interworking function and the called terminal and to change the connection between the calling terminal and the interworking function to the second type of connection, in response to the checking result of said checking unit.

21. A system according to claim 20 , wherein said determining unit is provided in a network element arranged between the calling terminal and said called terminal, and is configured to perform a monitoring operation.

22. A system according to claim 21 , wherein a connection fallback from said first type of connection to said second type of connection is performed in said network element.

23. A system according to claim 21 , wherein at least one type of connection supported by said called terminal is determined as said second type of connection in said determining unit by monitoring a signaling for call establishment, wherein said connection control unit is configured to re-establish the call based on the determination result.

24. A system according to claim 23 , wherein said connection control unit is arranged at said calling terminal, and wherein the determination result is signaled by said determining unit to said calling terminal.

25. A system according to claim 21 , wherein said network element is an interworking unit.

26. A system according to claim 25 , wherein said interworking unit is configured to check said first type of connection.

27. A system according to claim 20 , wherein said first type of connection is a multimedia connection.

28. A system according to claim 20 , wherein said second type of connection is a speech connection.

29. A system according to claim 20 , wherein said determining unit is configured to determine said second type of connection on the basis of an information obtained from said handshake processing.

30. A system according to claim 20 , wherein said determining unit is configured to determine said second type of connection by performing another handshake processing with said called terminal.

31. A system according to claim 20 , wherein said determining unit is configured to determine said second type of connection on the basis of the calling number of said called terminal.

32. A system according to claim 20 , wherein said determining unit is configured to determine said second type of connection on the basis of a predetermined priority order.

33. An interworking function, comprising:

negotiating means for adapting different protocol features used for connections with a calling terminal and a called terminal, said negotiating means being configured to, when receiving a request to establish a connection of a first type using first protocol features from a calling terminal, perform a setup processing according to the first protocol features used for the first type of connection with the called terminal;

determining means for determining a second type of connection;

checking means for checking a result of said setup processing so as to indicate whether the setup processing according to the first protocol features has been successful; and

connection control means for establishing said second type of connection between with the called terminal and changing the connection with the calling terminal to the second type of connection, in response to the checking result of said checking means.

34. A system for establishing a connection in a telecommunication network comprising different protocols, the system comprising:

negotiating means implemented as an interworking function for adapting the different protocol features used for a connection between a calling terminal and the interworking function and the interworking function and a called terminal, said negotiating means being adapted for, when receiving at the interworking function from a calling terminal a request to establish a connection of a first type using first protocol features, performing a setup processing according to the first protocol features used for the first type of connection between the interworking function and the called terminal;

determining means for determining a second type of connection;

checking means for checking a result of said setup processing so as to indicate whether or not the setup processing according to the first protocol features has been successful; and

connection control means for establishing said second type of connection between the interworking function and the called terminal and changing the connection between the calling terminal and the interworking function to the second type of connection, in response to the checking result of said checking means.

35. An interworking function, comprising:

a negotiating unit configured to adapt different protocol features used for connections with a calling terminal and a called terminal, said negotiating unit being configured to, when receiving a request to establish a connection of a first type using first protocol features from a calling terminal, perform a setup processing according to the first protocol features used for the first type of connection with the called terminal;

a determining unit configured to determine a second type of connection;

a checking unit configured to check a result of said setup processing so as to indicate whether the setup processing according to the first protocol features has been successful; and

a connection control unit configured to establish said second type of connection between with the called terminal and to change the connection with the calling terminal to the second type of connection, in response to the checking result of said checking unit.