System, device and method for providing call forwarding in dual subscription mode

• US 20040184435A1
• Filed: 12/10/2003
• Published: 09/23/2004
• Est. Priority Date: 06/20/2001
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Westman, Ilkka
• Granted Patent: US 7,403,517 B2
• Time in Patent Office: Days
• US Class Current: 370/349
• 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
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/02 Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

The invention relates to a method and system for providing interworking between a first and a second network of different types, preferably an IMS and a CS (Circuit-Switched) network. A call received by the first network and directed to a terminal unregistered from the first network, is forwarded to the second network, whereas when the call is received by the second network and is directed to a terminal unregistered from the second network, the call is not forwarded to the first network. The same identifier, preferably the same E.164 number, is used in both networks for identifying the called terminal. Preferably, the first network is informed on the registration of the terminal to the second network, the first network using this information as basis for the decision whether or not to route a call to the second network.

Claims

1. Method for providing interworking between a first and a second network of different types, wherein a terminal can be registered to the first network and/or to the second network, wherein a session request, e.g. a call, received by the first network and directed to a terminal unregistered from the first network, is forwarded to the second network, whereas when the session request is received by the second network and is directed to a terminal unregistered from the second network, the session request is not forwarded to the first network.

2. Method according to claim 1, wherein the first network is an IP-based network, preferably an IMS (IMS;

IP Multimedia Subsystem) network, and the second network is a CS (Circuit-Switched) network.

3. Method according to claim 1 or 2, wherein the same identifier, preferably the same E.164 number, is used in both networks for identifying the called terminal.

4. Method according to any one of the preceding claims, wherein the terminal is informed, preferably after every location update, on its registration in the second network.

5. Method according to any one of the preceding claims, wherein the first network is informed on the registration of the terminal to the second network, the first network using this information as basis for the decision whether or not to route a session request to the second network.

6. Method according to any one of the preceding claims, wherein after a location update in the second network, the terminal sends a message/information to the first network, the first network recording the time of the location update.

7. Method according to any one of the preceding claims, wherein, when the dual terminal is switched off, the terminal sends a message/information to the first network indicating the switching-off, the first network recording the state “

switched off”

i.e. “

unregistered from second network”

.

8. Method according to any one of the preceding claims, wherein, when the terminal unregisters from the second network, the terminal sends a message/information to the first network indicating that the terminal will unregister from the second network, the first network recording the state “

unregistered from second network”

.

9. Method according to any one of the preceding claims, wherein information about registration in the first network is continuously available in a server.

10. Method according to any one of the preceding claims, wherein, when the terminal is not registered in the first network, it is checked whether the terminal is registered in the second network.

11. Method according to claim 10, wherein, for checking whether the terminal is registered in the second network, information gathered from the terminal is utilized.

12. Method according to any one of the preceding claims, wherein, when detecting that the terminal is unregistered from the second network, the session request is not forwarded to the second network, whereas, when detecting that the terminal is registered to the second network, the session request is forwarded to the second network.

13. Method according to any one of the preceding claims, wherein the time duration elapsed since the time point of registration of the terminal to the second network is checked, and when the time duration is shorter than a certain period, the session request is forwarded to the second network, otherwise the session request is not forwarded.

14. Method according to any one of the preceding claims, wherein the first network provides a session forwarding service that is used when the subscriber is not reachable in the first network and the session request characteristics indicate that the session request can be successfully routed to the second network.

15. Method according to any one of the preceding claims, wherein the session forwarding service is a service for conditional voice call forwarding on mobile not reachable in the first network”

.

16. Method according to any one of the preceding claims, wherein one of the components of the first network checks whether the connection request to terminal 11 is a voice call request or a request of another type that can be successfully routed to the second network, and wherein the forwarding service is continued only when detecting, in this checking step, that the requested connection represents a voice call.

17. Method according to any one of the preceding claims, wherein the first network inspects, at least when the terminal is unregistered from the network 12, session characteristics of the intended session for checking the possibility of successfully forwarding the session to the second network.

18. Method according to any one of the preceding claims, wherein, when the first network 12 receives a session set-up request including session or call characteristics, it sends this request or at least a request including the session characteristics to an entity which checks, at least when the terminating terminal is unregistered from the first network, the session characteristics for deciding whether or not this session can be routed to the second network.

19. Method according to any one of the preceding claims, wherein an entity of the first network checks whether a media gateway of the first network is able to translate the traffic content of the requested session to a form appropriate for forwarding it to the second network, and, when no proper conversion is available, the entity decides not to forward the session.

20. Method according to any one of the preceding claims, wherein, when the first network detects that the session, e.g. a video call or video stream, can not be successfully routed to the second network, the first network routes such a session to an appropriate entity such as a Video Mail System.

21. Method according to any one of the preceding claims, wherein the first network is structured to route a session directed to an unregistered terminal directly to a media gateway, and, when the gateway returns an error message because of lack of conversion of the traffic and/or signalling of the session, an entity of the first network is addressed which decides how to further proceed with the requested session.

22. Method according to claim 21, wherein the entity analyzes the session characteristics and instructs the first network to forward, if possible, the session e.g. to an appropriate mail system such as video mail system.

23. Method according to any one of the preceding claims, wherein an interface between an S-CSCF and an entity of the first network use SIP+ or is implemented as a Service Control Point (SCP).

24. System for providing interworking between a first and a second network of different types, wherein a terminal can be registered to the first network and/or to the second network, wherein the system is adapted to forward a session request received by the first network and directed to a terminal unregistered from the first network, to the second network, whereas when the session request is received by the second network and is directed to a terminal unregistered from the second network, the system is adapted not to forward the session request to the first network.

25. System according to claim 24, wherein the first network is an IP-based network, preferably an IMS (IMS;

IP Multimedia Subsystem) network, and the second network is a CS (Circuit-Switched) network.

26. System according to claim 24 or 25, wherein the same identifier, preferably the same E.164 number, is used in both networks for identifying the called terminal.

27. System according to any one of the preceding system claims, wherein the system is adapted to inform the terminal, preferably after every location update, on its registration in the second network.

28. System according to any one of the preceding system claims, wherein the system is adapted to inform the first network on the registration of the terminal to the second network, the first network using this information as basis for the decision whether or not to route a session request to the second network.

29. System according to any one of the preceding system claims, wherein after each successful location update in the second network, the terminal is adapted to send a message/information to the first network, the first network recording the time of the successful location update.

30. System according to any one of the preceding system claims, wherein the terminal is adapted to send, when the terminal is switched off, a message/information to the first network indicating the switching-off, the first network recording the state “

switched off”

i.e. “

unregistered from second network”

.

31. System according to any one of the preceding system claims, wherein the terminal is adapted to send, when the terminal unregisters from the second network, a message/information to the first network indicating that the terminal will unregister from the second network, the first network recording the state “

unregistered from second network”

.

32. System according to any one of the preceding system claims, wherein the first network comprises a server which stores information about registration of the terminal in the first network.

33. System according to any one of the preceding system claims, wherein the first network is adapted to check, when the terminal is not registered in the first network, whether the terminal is registered in the second network.

34. System according to claim 33, wherein, for checking whether the terminal is registered in the second network, information gathered from the terminal is utilized.

35. System according to any one of the preceding system claims, wherein the system is adapted, when detecting that the terminal is unregistered from the second network, not to forward a session request to the second network, whereas, when detecting that the terminal is registered to the second network, the session request is forwarded to the second network.

36. System according to any one of the preceding system claims, wherein the system is adapted to check the time duration elapsed since the time point of registration of the terminal to the second network, and to forward, when the time duration is shorter than a certain period, the session request to the second network, which otherwise is not forwarded.

37. System according to any one of the preceding system claims, wherein the first network provides a supplementary service:

“

Conditional voice call forwarding on mobile not reachable in the first network”

.

38. System according to any one of the preceding system claims, wherein first network is adapted to check whether a connection request to terminal 11 is a voice call request or a request of another type, and to continue the call forwarding to the second network only when detecting that the requested connection represents a voice call.

39. System according to any one of the preceding system claims, wherein the first network provides a session forwarding service that is used when the subscriber is not reachable in the first network and the session request characteristics indicate that the session request can be successfully routed to the second network.

40. System according to any one of the preceding system claims, wherein the session forwarding service is a service for conditional voice call forwarding on mobile not reachable in the first network”

.

41. System according to any one of the preceding system claims, wherein one of the components of the first network checks whether the connection request to terminal 11 is a voice call request or a request of another type that can be successfully routed to the second network, and wherein the forwarding service is continued only when detecting, in this checking step, that the requested connection represents a voice call.

42. System according to any one of the preceding system claims, wherein the first network inspects, at least when the terminal is unregistered from the network 12, session characteristics of the intended session for checking the possibility of successfully forwarding the session to the second network.

43. System according to any one of the preceding system claims, wherein, when the first network receives a session set-up request including session or call characteristics, it sends this request or at least a request including the session characteristics to an entity which checks, at least when the terminating terminal is unregistered from the first network, the session characteristics for deciding whether or not this session can be routed to the second network.

44. System according to any one of the preceding system claims, wherein an entity of the first network checks whether a media gateway of the first network is able to translate the traffic content of the requested session to a form appropriate for forwarding it to the second network, and, when no proper conversion is available, the entity decides not to forward the session.

45. System according to any one of the preceding system claims, wherein, when the first network detects that the session, e.g. a video call or video stream, can not be successfully routed to the second network, the first network routes such a session to an appropriate entity such as a Video Mail System.

46. System according to any one of the preceding system claims, wherein the first network is structured to route a session directed to an unregistered terminal directly to a media gateway, and, when the gateway returns an error message because of lack of conversion of the traffic and/or signalling of the session, an entity of the first network is addressed which decides how to further proceed with the requested session.

47. System according to claim 46, wherein the entity analyzes the session characteristics and instructs the first network to forward, if possible, the session e.g. to an appropriate mail system such as video mail system.

48. System according to any one of the preceding system claims, wherein an interface between an S-CSCF and an entity of the first network use SIP+ or is implemented as a Service Control Point (SCP).

49. Method for providing interworking between a first and a second network of different types, wherein a subscriber entity can be registered to the first network and/or to the second network, wherein a call received by the first network and directed to a subscriber entity unregistered from the first network, is forwardable to the second network,

the forwarding step comprises the following steps:

issueing an enquiry to service execution means, the enquiry carrying call characteristics,

the service execution means arranged to be aware of the conversion capabilities of a gateway means providing media stream conversion between said first and second network,

the service execution means inspecting call characteristics,

the service execution means making a decision as to whether the call characteristics are such that at least one media stream related to the call can be converted by the gateway means,

issueing from the service execution means a forwarding request to the second network based on the said decision.

50. System for providing interworking between a first and a second network of different types, wherein a subscriber entity can be registered to the first network and/or to the second network, wherein a call received by the first network and directed to a subscriber entity unregistered from the first network, is forwardable to the second network,

the system comprising means for carry-out the following steps for providing the call forwarding:

issueing an enquiry to service execution means, the enquiry carrying call characteristics,

the service execution means arranged to be aware of the conversion capabilities of a gateway means providing media stream conversion between said first and second network,

the service execution means inspecting call characteristics,

the service execution means making a decision as to whether the call characteristics are such that at least one media stream related to the call can be converted by the gateway means,

issueing from the service execution means a forwarding request to the second network based on the said decision.

51. Method for providing interworking between a first and a second network of different types, wherein a terminal can be registered to the first network and/or to the second network, wherein a session request received by the first network and directed to a terminal unregistered from the first network, is forwarded to the second network together with an information indicating that the session request was forwarded from the first network.

52. Method according to claim 51, wherein the first and/or second network are designed to check the information and to suppress the forwarding of a session request forwarded from another network back to this another network.

53. Method according to claim 51 or 52, wherein the information is an identifier for identifying the unregistered terminal, the identifier being changed when forwarding the session request from one of the networks to another one of the networks.

54. System for providing interworking between a first and a second network of different types, wherein a terminal can be registered to the first network and/or to the second network, wherein the system is adapted to forward a session request received by the first network and directed to a terminal unregistered from the first network, to the second network together with an information indicating that the session request was forwarded from the first network.

55. System according to claim 54, wherein the first and/or second network are designed to check the information and to suppress the forwarding of a session request forwarded from another network back to this another network.

56. System according to claim 54 or 55, wherein the information is an identifier for identifying the unregistered terminal, the identifier being changed when forwarding the session request from one of the networks to another one of the networks.