Routing a call between different types of networks

• US 7,027,433 B2
• Filed: 06/20/2001
• Issued: 04/11/2006
• Est. Priority Date: 06/20/2001
• Status: Expired due to Term

• Current Assignee: III Holdings 3, LLC (Intellectual Ventures LLC)
• Original Assignee: Nokia Corporation
• Inventors: Tuohino, Markku, Hänninen, Jukka P.
• Primary Examiner(s): Ngo, Ricky
• Assistant Examiner(s): Juntima, Nittaya
• Application Number:
  US09/885,636
• Publication Number:
  US 20020196775A1
• Time in Patent Office: 1,756 Days
• Field of Search: 370352-356, 370/401, 370/466, 370/400, 370/349, 370/338, 370/328, 370/313, 455/433, 455/445, 455/422.1
• 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
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1095 Inter-network session transfer or sharing

Abstract

The basic idea is to enhance functionality of the Signaling Relay Function for support of MNP (MNP-SRF) so that the normal HLR query in the circuit switched domain is bypassed and the call is routed to an IMS domain. The SLRF, upon receipt from a GMSC a SRI message containing the real MSISDN number of the called party, translates the MSISDN number to a new MSISDN number and responds to the query by sending a message containing routing information to the IMS domain and the new MSISDN number. Alternatively, the original MSISDN number is used in the response message but a certain identifier is then added into the message. Then the called subscriber is first tried to reach in the IMS domain where the subscriber is likely residing. In case the subscriber yet resides in the circuit switched domain the call is routed from the IMS domain back to the circuit switched domain and not until then the normal HRL query is performed.

Claims

1. A method of routing a call from a circuit switched telecommunications network to a packet switched telecommunications network, wherein the circuit switched telecommunications network is provided with an access to a user register, comprising the steps of:

sending from a first network element of the circuit switched telecommunications network a first routing information query to an second network element, said query including a destination identifier of a called party,

sending a response message to the first network element, said response message comprising routing information to the packet switched telecommunications network,

sending from the first network element, according the routing information, a set-up message to the packet switched telecommunications network, said set-up message comprising the destination identifier of the called party,

and when the call has been returned from the packet switched telecommunications network back to the circuit switched telecommunications network;

sending from the first network element a second routing information query to the second network element,

sending in response to the second routing information query a query message to the user register.

2. The method as in claim 1, wherein the second element is an element performing subscriber locator routing function.

3. The method as in claim 1, further comprising the step of:

including to the second routing information query the destination identifier of the called party.

4. The method as in claim 1, further comprising the step of:

including to the second routing information query a second identifier in order to differentiate the first information query message and the second information query message.

5. The method as in claim 4, further comprising the step of:

including in the packet switched network side the second identifier to the message returning the call from the packet switched network to the circuit switched network.

6. The method as in claim 1, further comprising the step of:

forming the query message to the user register as a standard query message according to circuit switched telecommunications network.

7. The method as in claim 1, further comprising the step of:

including into said query message the first identifier of the called party.

8. The method as in claim 1, further comprising the step of:

returning the call from packet switched network to a different first network element than the one sending the set up message to the packet switched network.

9. The method as in claim 1, further comprising the step of:

sending from the user register to the first network element routing information for routing the call to the called party.

10. The method as in claim 1, wherein the destination identifier is an E.164 number.

11. The method as in claim 1, wherein the first network element is a gateway mobile switching center of a mobile telecommunications network.

12. The method as in claim 1, wherein the user register is a home location register of a mobile telecommunications network.

13. The method as in claim 1, wherein the packet switched telecommunications network is an Internet multimedia subsystem.

14. A method for routing a call from a circuit switched telecommunications network to a packet switched telecommunications network, wherein the circuit switched telecommunications network is provided with an access to an user register, comprising the steps of:

sending from a first network element a first routing information query to a second network element, said query including the destination identifier of a called party,

allocating a new destination identifier to the call,

sending a response message to the first network element, said response message comprising routing information to the packet switched telecommunications network,

sending from the first network element, according the routing information, a set-up message to the packet switched telecommunications network, said set-up message including the new destination identifier of the called party,

and when the call has been returned from the packet switched telecommunications network back to the circuit switched telecommunications network;

sending from the first network element a second routing information query to the second network element,

sending in response to the second routing information query a query message to the user register.

15. The method as in claim 14, wherein the second element is an element performing subscriber locator routing function.

16. The method as in claim 14, further comprising the step of:

including to the second routing information query the new destination identifier of the called party.

17. The method as in claim 14, further comprising the step of:

forming the query message to the user register as a standard query message according circuit switched telecommunications network.

18. The method as in claim 17, further comprising the step of:

including into said query message the first identifier of the called party.

19. The method as in claim 14, further comprising the step of:

returning the call from packet switched network to a different first network element than the one sending the set up message to the packet switched network.

20. The method as in claim 14, further comprising the step of:

sending from the user register to the first network element routing information for routing the call to the called party.

21. The method as in claim 14, wherein the destination identifier is an E.164 number.

22. The method as in claim 14, wherein the first network element is a gateway mobile switching center of a mobile telecommunications network.

23. The method as in claim 14, wherein the user register is a home location register of a mobile telecommunications network.

24. The method as in claim 14, wherein the packet switched telecommunications network is an Internet multimedia subsystem.

25. A network element for receiving routing information queries from and sending responses to a first network element in a circuit switched telecommunications network,

said network element having a signaling connection with a user register and, said network element comprising:

means for receiving a first routing information query from the first network element, said query including a destination identifier of a called party,

means for forming and sending a response to the first routing information query, to the first network element, the response comprising routing information to a packet switched telecommunications network,

means for receiving a second routing information query relating to the called party from the first network element, and

means for forming a query message for sending to the user register in response to the second routing information query.

26. A network element as in claim 25, further comprising:

means for allocating, in response to the first routing inquiry, a new destination identifier and

means for including the new destination identifier to the routing information sent to the first network element.

27. A network element as in claim 25, further comprising:

means for including the destination identifier to the query message sent to the user register.

28. A network element for use in a method of routing a call from a circuit switched telecommunications network to a packet switched telecommunications network, wherein the circuit switched telecommunications network is provided with an access to a user register, the network element comprising:

a transmitter configured to send a first routing information query to an second network element, said query including a destination identifier of a called party,

a receiver configured to receive a response message, said response message comprising routing information to the packet switched telecommunications network,

a transmitter configured to send, according the routing information, a set-up message to the packet switched telecommunications network, said set-up message comprising the destination identifier of the called party,

a transmitter configured to send a second routing information query to the second network element in response to the call having been returned from the packet switched telecommunications network back to the circuit switched telecommunications network.

29. The network element as in claim 28, wherein the network element is a gateway mobile switching center of a mobile telecommunications network.

30. A network element for use in a method for routing a call from a circuit switched telecommunications network to a packet switched telecommunications network, wherein the circuit switched telecommunications network is provided with an access to an user register, the network element comprising:

a transmitter configured to send a first routing information query to a second network element, said query including the destination identifier of a called party,

a receiver configured to receive a response message, said response message comprising routing information to the packet switched telecommunications network and a new destination identifier allocated to the call,

a transmitter configured to send, according the routing information, a set-up message to the packet switched telecommunications network, said set-up message including the new destination identifier of the called party,

a transmitter configured to send a second routing information query to the second network element in response to the call having been returned from the packet switched telecommunications network back to the circuit switched telecommunications network.

31. The network element as in claim 30, wherein the network element is a gateway mobile switching center of a mobile telecommunications network.