1. An apparatus comprising:
a transceiver configured to communicate with a first mobile communication network a second mobile communication network, wherein the transceiver communicates with only one mobile communication network at a time; and a processor that: uses a first service in the first mobile communication network; and determines to suspend the first service in order to use a second service in the second mobile communication network; wherein the transceiver sends a first mobility management (�MM�) message to the first mobile communication network, said first MM message indicating that a first registration and the first service are to be suspended, and receives a second message as reply to the first MM message, said second message indicating that the first registration and the first service are successfully suspended, and wherein the processor uses the second service in the second mobile communication network without using the first service.
2. The apparatus of claim 1,
wherein the processor further determines to resume a data connection to the first mobile communication network; wherein the transceiver sends, to the first mobile communication network, a third MM message indicating that the first registration and the first service are to be resumed; and wherein the processor resumes using the first service in the first mobile communication network in response to the first mobile communication network responding to the third MM message, said third MM message being selected from the group consisting of: a registration request, a service request, an attach request, and a tracking area update request.
3. The apparatus of claim 2, wherein the transceiver sending the third MM message comprises sending a registration request message to the first mobile communication network that indicates which data connections corresponding to the first service are to be resumed.
4. The apparatus of claim 1, wherein the first MM message indicates that the UE is temporarily unreachable in the first mobile communication network.
5. (canceled)
6. The apparatus of claim 1, wherein the transceiver sending the first MM message comprises the transceiver sending a non-access stratum (�NAS�) MM message to the second mobile communication network while in an idle state with respect to the first mobile communication network, said NAS MM message indicating that a registration with the first mobile communication network is not to be cancelled.
7. The apparatus of claim 6, wherein the NAS MM message sent to the second mobile communication network further includes an indication to suspend the first service and that data connection context associated with the first service is to be preserved.
8. (canceled)
9. (canceled)
10. The apparatus of claim 1, wherein the transceiver sending the first MM message comprises the transceiver sending a non-access stratum (�NAS�) MM message to the first mobile communication network while in a connected state with respect to the first mobile communication network, said NAS MM message requesting suspension of the first service.
11. The apparatus of claim 10, wherein the NAS MM message includes a cause parameter, said cause parameter indicating that the apparatus requires the service in the second mobile communication network that is unavailable in the first mobile communication network.
12. The apparatus of claim 1, wherein the processor preserves data connection context associated with the first service while using the second service in the second mobile communication network.
13. The apparatus of claim 1, wherein the apparatus is a user equipment capable of dual registration with the first and second mobile communication networks and the transceiver is incapable of both dual reception and dual transmission with the first and second mobile communication networks.
14. A method comprising:
using a first service in a first mobile communication network; determining, at a remote unit, to suspend the first service in order to use a second service in a second mobile communication network, wherein the remote unit communicates with only one mobile communication network at a time; sending a first mobility management (�MM�) message to the first mobile communication network, said first MM message indicating that a first registration and the first service are to be suspended; receiving a second message as reply to the first MM message, said second message indicating that the first registration and the first service are successfully suspended, and using the second service in the second mobile communication network.
15. The method of claim 14, further comprising:
determining to discontinue the second service resume a data connection to the first communication network; and sending, to the first mobile communication network, a third MM message indicating that the first registration and the first service are to be resumed; and resuming the first service in response to the first mobile communication network responding to the third MM message, said third MM message being selected from the group consisting of: a registration request, a service request, an attach request, and a tracking area update request.
16. The method of claim 15, wherein sending the third MM message comprises sending the registration request message to the first mobile communication network, wherein the registration request message indicates which data connections corresponding to the first service are to be resumed.
17. The method of claim 15, wherein the first MM message indicates that the UE is temporarily unreachable in the first mobile communication network.
18. (canceled)
19. The method of claim 14, wherein sending the first MM message comprises transmitting a non-access stratum (�NAS�) MM message to the second mobile communication network while in an idle state with respect to the first mobile communication network, said NAS MM message indicating that a registration with the first mobile communication network is not to be cancelled.
20. The method of claim 19, wherein the NAS MM message sent to the second mobile communication network further includes an indication to suspend the first service and to preserve one or more data connection contexts associated with the first service.
21. (canceled)
22. (canceled)
23. The method of claim 14, wherein sending the first MM message comprises transmitting a non-access stratum (�NAS�) MM message to the first mobile communication network while in a connected state with respect to the first mobile communication network, said NAS MM message requesting suspension of the first service.
24. The method of claim 23, wherein the NAS MM message includes a cause parameter, said cause parameter indicating that the apparatus requires the service in the second mobile communication network that is unavailable in the first mobile communication network.
25. The method of claim 14, further comprising preserving data connection context associated with the first service while using the second service in the second mobile communication network.
26. The method of claim 14, wherein the remote unit is a user equipment capable of dual registration with the first and second mobile communication networks and having a transceiver incapable of both dual reception and dual transmission with the first and second mobile communication networks.
27. (canceled)
28. (canceled)
29. (canceled)
30. (canceled)
31. (canceled)
32. (canceled)
33. (canceled)
34. (canceled)
35. (canceled)
36. (canceled)
37. (canceled)
38. (canceled)
39. (canceled)
40. (canceled)
41. (canceled)
42. (canceled)
43. (canceled)
44. (canceled)