Capability update during call

1. A method, comprising:

providing a first mobile device on a first network and a second mobile device on a second network, wherein the first network supports Circuit Switched (CS) and Packet Switched (PS) data, and the second network supports only CS;

setting up a call between the first mobile device and the second mobile device through configuration of a communications link that allows the first mobile device and the second mobile device to exchange CS data;

providing a capability update message from the second device to the first device, during the call, in response to a hand over of the second mobile device to a network that supports CS data and PS data, wherein the capability update message indicates to the first mobile device that the second mobile device is on a network capable of supporting both CS data and PS data;

reconfiguring, during the call, by the first and second mobile devices after providing the capability update message to the first mobile device, the communications link to allow the first mobile device and the second mobile device to exchange concurrently both CS data and PS data, wherein reconfiguring after providing the capability update message includes registering the first and second mobile devices for PS services.

2. The method of claim 1 , wherein the step of providing a capability update message comprises:

sending a message indicating that the at least one of the first mobile device and the mobile second device is capable of supporting PS data.

3. The method of claim 1 , wherein the step of reconfiguring comprises:

setting up a combination CS voice call and PS call between the first mobile device and the second mobile device.

4. The method of claim 3 , wherein the step of setting up the combination CS voice call and PS call comprises:

enabling the first mobile device and second mobile device to concurrently exchange at least one of multimedia messaging service (MMS) data and IP Multimedia Subsystem (IMS) data.

5. The method of claim 1 , wherein the step of exchanging concurrently CS data and PS data includes:

exchanging MMS messages between the first mobile device and the second mobile device.

6. The method of claim 1 , wherein the step of setting up the call comprises:

setting up a CS voice call between the first mobile device and the second mobile device.

7. The method of claim 1 , wherein the capability update message sent from the second mobile device to the first mobile device passes transparently through the network.

8. A mobile device, comprising:

an interface to a first communications network that supports only Circuit Switched (CS) data; and

a processor; wherein the processor is configured to set up a call with another mobile device interfaced to a second communications network that supports CS data and Packet Switched (PS) data, during which CS data is exchanged, to provide a capability update message to the another mobile device, during the call, in response to a hand over of the mobile device to a network that supports CS data and PS data, wherein the capability update messages indicates to the another mobile device that the mobile device is on a network capable supporting both CS data and PS data during the call, wherein the process is further configured to setup a combination CS and PS call after providing the capability update message, wherein setting up a combination CS and PS call after sending the capability update message includes the processor being configured to register the mobile device for PS services.

9. The mobile device of claim 8 , wherein the processor is configured to set up the call by setting up a CS voice call with the other mobile device and is further configured to set up a combination CS voice call and PS call after providing the capability update message.

10. The mobile device of claim 8 , wherein the processor is adapted to exchange MMS messages with the other mobile device after providing the capability update message.

11. The mobile device of claim 8 , wherein the processor is adapted to register with an IMS server and exchange IMS messages and media with the mobile device after providing the capability update message.