Synchronizing call feature data between an IMS network and a legacy network

1. A system comprising:

an IP Multimedia Subsystem (IMS) subscriber server operable to store feature data for an IMS call feature provided to a dual mode device by an IMS network;

the IMS subscriber server further operable to receive a notification from an application server indicating a change to the feature data in the IMS network made by an end user of the dual mode device, and to update corresponding feature data stored in a legacy subscriber server of a legacy network based on the change to the feature data in the IMS network.

2. The system of claim 1 wherein:

the IMS subscriber server is further operable to receive a transparent data block defined for a Diameter Sh interface indicating the change to the feature data in the IMS network, to interpret the transparent data block to identify the change to the feature data in the IMS network, to validate the change to the feature data based on rules for the legacy subscriber server, and to update the corresponding feature data stored in the legacy subscriber server based on the change to the feature data in the IMS network provided in the transparent data block.

3. The system of claim 2 wherein the transparent data block indicates a change to feature data for a single IMS call feature.

4. The system of claim 1 wherein:

the IMS subscriber server is further operable to monitor the legacy subscriber server, to identify a change to feature data in the legacy network, and to notify the application server of the change to the feature data in the legacy network.

5. The system of claim 4 wherein:

the IMS subscriber server is further operable to receive a subscription request from the application server requesting to be notified of a change to the feature data in the legacy network; and

responsive to identifying the change to the feature data in the legacy network, the IMS subscriber server is further operable to format a transparent data block defined for a Diameter Sh interface indicating the change to the feature data in the legacy network, and to transmit the transparent data block to the application server.

6. The system of claim 1 wherein the legacy subscriber server and the IMS subscriber server comprise a combined Home Location Register (HLR)/Home Subscriber Server (HSS).

7. The system of claim 1 wherein the legacy network comprises a Universal Mobile Telecommunications System (UMTS) network.

8. A method comprising:

storing feature data in an IP Multimedia Subsystem (IMS) subscriber server for an IMS call feature provided to a dual mode device by an IMS network;

receiving a notification from an application server indicating a change to the feature data in the IMS network made by an end user of the dual mode device; and

updating corresponding feature data stored in a legacy subscriber server of a legacy network based on the change to the feature data in the IMS network.

9. The method of claim 8 wherein:

the step of receiving the notification from the application server comprises:

receiving a transparent data block defined for a Diameter Sh interface indicating the change to the feature data in the IMS network, and

interpreting the transparent data block to identify the change to the feature data in the IMS network; and

the step of updating the corresponding feature data stored in the legacy subscriber server comprises:

validating the change to the feature data based on rules for the legacy subscriber server, and

updating the corresponding feature data stored in the legacy subscriber server based on the change to the feature data in the IMS network provided in the transparent data block.

10. The method of claim 9 wherein the transparent data block indicates a change to feature data for a single IMS call feature.

11. The method of claim 8 further comprising:

monitoring the legacy subscriber server;

identifying a change to feature data in the legacy network; and

notifying the application server of the change to the feature data in the legacy network.

12. The method of claim 11 further comprising:

receiving a subscription request from the application server requesting to be notified of a change to the feature data in the legacy network; and

responsive to identifying the change to the feature data in the legacy network, the method further comprises formatting a transparent data block defined for a Diameter Sh interface indicating the change to the feature data in the legacy network, and transmitting the transparent data block to the application server.

13. The method of claim 8 wherein the legacy subscriber server and the IMS subscriber server comprise a combined Home Location Register (HLR)/Home Subscriber Server (HSS).

14. The method of claim 8 wherein the legacy network comprises a Universal Mobile Telecommunications System (UMTS) network.

15. A system comprising:

an application server of an IP Multimedia Subsystem (IMS) network that is operable to provide an IMS call feature to a dual mode device based on feature data defined for an end user of the dual mode device in the IMS network;

the application server further operable to receive a change to the feature data from the end user of the dual mode device, and to update corresponding feature data of a legacy call feature in a legacy network based on the change to the feature data in the IMS network so that the feature data is synchronized between the IMS network and the legacy network.

16. The system of claim 15 wherein:

the application server is further operable to notify an IMS subscriber server of the change to the feature data in the IMS network to in turn cause the IMS subscriber server to update the corresponding feature data in the legacy network based on the change to the feature data in the IMS network.

17. The system of claim 16 wherein:

the application server is further operable to format a transparent data block defined for a Diameter Sh interface indicating the change to the feature data in the IMS network, and to transmit the transparent data block to the IMS subscriber server.

18. The system of claim 15 wherein:

the application server is further operable to transmit a subscription request to the IMS subscriber server requesting to be notified of a change to feature data in the legacy network, and to receive a notification from the IMS subscriber server indicating a change to feature data in the legacy network.

19. The system of claim 18 wherein:

the application server is further operable to process a transparent data block defined for a Diameter Sh interface to identify the change to the feature data in the legacy network, and to update corresponding feature data in the IMS network.

20. The system of claim 15 wherein the legacy network comprises a Universal Mobile Telecommunications System (UMTS) network.