Method for supporting circuit switched interworking

1. A method of switched interworking, the method comprising: receiving a voice call component in circuit switched (CS) domain at a wireless transmit/receive unit (WTRU) via a CS domain entity and a radio access network (RAN), wherein the voice call component is a translation of a voice call component in an of IP multimedia core network subsystem (IMS) session content in the IMS domain, the IMS session content including the voice call component in the IMS domain and media content in the IMS domain; and

receiving the media content in IMS domain at the WTRU via a packet-switched (PS) domain entity and the RAN.

2. The method of claim 1 , wherein the voice call component is received via a network based on Global System for Mobile Communication (GSM) or 3GPP2 Code Division Multiple Access (CDMA) technology.

3. The method of claim 1 , wherein the voice call component in IMS domain is in a Voice Over Internet Protocol (VoIP) format.

4. The method of claim 1 , further comprising sending a SIP BYE message from the WTRU to release the session.

5. The method of claim 1 , further comprising requesting participation in the session.

6. The method of claim 5 , wherein the requesting participation comprises a Session Initiation Protocol (SIP) invite message.

7. The method of claim 5 , further comprising receiving a response message to the request to participate in the session.

8. The method of claim 7 , wherein the response message is a SIP OK message.

9. The method of claim 1 wherein the voice call component in CS domain and the voice call component in IMS domain include data for the same call.

10. A wireless transmit/receive unit (WTRU), the WTRU comprising: a circuit switched (CS) domain device configured to process a voice call via a CS domain entity and a radio access network (RAN), the voice call being a translation of a voice call component of in an IP multimedia core network subsystem (IMS) session content that includes the voice call component in IMS domain and media content in IMS domain; and an IMS domain device configured to process a media content session of the media content in the IMS domain via a packet-switched (PS) domain entity and the RAN.

11. The WTRU of claim 10 , wherein the voice call is received via a network based on Global System for Mobile Communication (GSM) or 3GPP2 Code Division Multiple Access (CDMA) technology.

12. The WTRU of claim 10 , wherein the voice call component in IMS domain is in a Voice over Internet Protocol (VoIP) format.

13. The WTRU of claim 10 , wherein the media content is received via a UMTS Terrestrial Radio Access Network (UTRAN).

14. The WTRU of claim 10 , wherein the IMS domain device is further configured to send data associated with the IMS session.

15. The WTRU of claim 10 , wherein the IMS domain device is further configured to receive a message to initiate establishment of the PS bearer for the media content session.

16. The WTRU of claim 10 , wherein the CS domain device is further configured to receive a message to initiate establishment of a CS bearer for the CS session.

17. The WTRU of claim 10 , wherein the IMS domain device is further configured to send a message to request participation in the session.

18. The WTRU of claim 17 , wherein the message is a SIP invite.

19. The WTRU of claim 10 , wherein the IMS domain device is further configured to receive a message responding to a participation message.

20. The WTRU of claim 19 , wherein the received message is a SIP OK message.