Method for SRVCC emergency call support

1. A method comprising:

receiving, at a home subscriber server, a first message comprising a generated value representing a session transfer number from an internet protocol multimedia subsystem, the session transfer number relating to a transfer of an emergency session from a first network to a second network and pointing to the internet protocol multimedia subsystem where the transfer of the emergency session occurs;

updating, by the home subscriber server, a user profile with the generated value representing the session transfer number for the emergency session, the user profile stored in the home subscriber server; and

sending, by the home subscriber server, a second message comprising the generated value representing the session transfer number.

2. The method of claim 1 , further comprising:

initiating a single radio voice call continuity operation to transfer the emergency session from the first network to the second network.

3. The method of claim 1 , wherein the first network is a packet switched network, and the second network is a circuit switched network.

4. The method of claim 1 , wherein the generated value representing the session transfer number is an international telecommunications union E.164 address.

5. The method of claim 1 , wherein the generated value representing the session transfer number identifies a service centralization continuity application server.

6. The method of claim 1 , wherein the internet protocol multimedia subsystem generates the generated value.

7. The method of claim 1 , wherein the first message is sent during at least one of an emergency session establishment and an emergency registration.

8. The method of claim 1 , wherein the second message provides information to update a home subscriber server user profile stored in a mobility management entity.

9. An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one processor, the at least one memory, and the computer program code configured to cause the apparatus to perform at least the following:

receive, at a home subscriber server, a first message comprising a generated value representing a session transfer number from an internet protocol multimedia subsystem, the session transfer number relating to a transfer of an emergency session from a first network to a second network and pointing to the internet protocol multimedia subsystem where the transfer of the emergency session occurs;

update, by the home subscriber server, a user profile with the generated value representing the session transfer number for the emergency session, the user profile stored in the home subscriber server; and

send, by the home subscriber server, a second message comprising the generated value representing the session transfer number.

10. The apparatus of claim 9 , wherein the apparatus is further caused to:

initiate a single radio voice call continuity operation to transfer the emergency session from the first network to the second network.

11. The apparatus of claim 9 , wherein the first network is a packet switched network, and the second network is a circuit switched network.

12. The apparatus of claim 9 , wherein the generated value representing the session transfer number is an international telecommunications union E.164 address.

13. The apparatus of claim 9 , wherein the generated value representing the session transfer number identifies a service centralization continuity application server.

14. The apparatus of claim 9 , wherein the internet protocol multimedia subsystem generates the generated value.

15. The apparatus of claim 9 , wherein the first message is sent during at least one of an emergency session establishment and an emergency registration.

16. The apparatus of claim 9 , wherein the second message provides information to update a home subscriber server user profile stored in a mobility management entity.

17. A computer program product comprising a non-transitory computer-readable medium encoded with instructions, that when executed by at least one processor, perform at least the following operations:

receiving, at a home subscriber server, a first message comprising a generated value representing a session transfer number from an internet protocol multimedia subsystem, the session transfer number relating to a transfer of an emergency session from a first network to a second network and pointing to the internet protocol multimedia subsystem where the transfer of the emergency session occurs;

updating, by the home subscriber server, a user profile with the generated value representing the session transfer number for the emergency session, the user profile stored in the home subscriber server; and

sending, by the home subscriber server, a second message comprising the generated value representing the session transfer number.

18. The computer-readable medium of claim 17 , the operations further comprising:

initiating a single radio voice call continuity operation to transfer the emergency session from the first network to the second network.

19. The computer-readable medium of claim 17 , wherein the first network is a packet switched network, and the second network is a circuit switched network.

20. The computer-readable medium of claim 17 , wherein the generated value representing the session transfer number is an international telecommunications union E.164 address.