Transitioning a video call between networks

1. A method for transitioning a video call from a Long Term Evolution (LTE) network to a legacy cellular network, the method comprising:

by a wireless communication device:

participating in a video call with a remote communication device via a first video call session established over a connection between the wireless communication device and the Long Term Evolution (LTE) network, the first video call session comprising a packet switched video stream carried over a first bearer and a voice over LTE (VoLTE) audio stream carried over a second bearer;

determining that a measured connection quality of the LTE network is less than a threshold connection quality;

transitioning to the legacy cellular network having a circuit switched domain by at least dropping the connection between the wireless communication device and the LTE network and without invoking a network coordinated handover, in response to determining that the measured connection quality of the LTE network is less than the threshold connection quality;

establishing a second video call session with the remote communication device on the legacy cellular network in response to transitioning to the legacy cellular network;

providing an indication, via a user interface of the wireless communication device, that the video call with the remote communication device is ongoing while transitioning to the legacy cellular network and establishing the second video call session; and

using the second video call session to continue the video call with the remote communication device on the legacy cellular network.

2. The method of claim 1 , further comprising the wireless communication device sending an indication to the remote communication device that the wireless communication device is transitioning between networks prior to transitioning to the legacy cellular network.

3. The method of claim 1 , further comprising the wireless communication device:

setting a timer in response to determining that the measured connection quality of the LTE network is less than the threshold connection quality; and

providing an indication, via the user interface of the wireless communication device, that the video call with the remote communication device has been dropped in an instance in which the second video call session is not established prior to expiry of the timer.

4. The method of claim 1 , wherein the LTE network does not support single radio voice call continuity (SRVCC) for transferring the VoLTE audio stream to the legacy cellular network.

5. The method of claim 1 , wherein the first video call session is dropped by the LTE network.

6. The method of claim 1 , wherein the measured connection quality comprises one or more of a received signal strength indicator (RSSI) of the LTE network, a reference signal received power (RSRP) of the LTE network, or a reference signal received quality (RSRQ) of the LTE network.

7. The method of claim 1 , wherein the legacy cellular network comprises one of a Wideband Code Division Multiple Access (WCDMA) network, Universal Mobile Telecommunications System (UMTS) network, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) network, CDMA2000 network, or Global System for Mobile Communications (GSM) network.

8. A wireless communication device comprising

at least one transceiver, the at least one transceiver configured to send wireless signals to and receive wireless signals from a first cellular network and a legacy cellular network;

and processing circuitry coupled with the at least one transceiver, the processing circuitry configured to control the wireless communication device to at least:

participate in a video call with a remote communication device via a first video call session established over a connection between the wireless communication device and the first cellular network, the first video call session comprising a packet switched video stream carried over a first bearer and a packet switched audio stream carried over a second bearer;

determine a degradation in connection quality of the first cellular network;

transition to the legacy cellular network having a circuit switched domain by at least dropping the connection between the wireless communication device and the first cellular network and without invoking a network coordinated handover, in response to the degradation in connection quality of the first cellular network;

establish a second video call session with the remote communication device on the legacy cellular network in response to transitioning to the legacy cellular network;

provide an indication, via a user interface of the wireless communication device, that the video call with the remote communication device is ongoing while transitioning to the legacy cellular network and establishing the second video call session; and

use the second video call session to continue the video call with the remote communication device on the legacy cellular network.

9. The wireless communication device of claim 8 , wherein the first cellular network is a Long Term Evolution (LTE) network, and wherein the second bearer is a voice over LTE (VoLTE) bearer.

10. The wireless communication device of claim 8 , wherein the processing circuitry is further configured to control the wireless communication device to determine the degradation in connection quality of the first cellular network at least in part by controlling the wireless communication device to determine that a measured connection quality of the first cellular network is less than a threshold connection quality.

11. The wireless communication device of claim 8 , wherein the processing circuitry is further configured to control the wireless communication device to send an indication to the remote communication device that the wireless communication device is transitioning between networks prior to transitioning to the legacy cellular network.

12. The wireless communication device of claim 8 , wherein the processing circuitry is further configured to control the wireless communication device to:

set a timer in response to the degradation in connection quality of the first cellular network; and

provide an indication, via the user interface of the wireless communication device, that the video call with the remote communication device has been dropped in an instance in which the second video call session is not established prior to expiry of the timer.

13. The wireless communication device of claim 8 , wherein the first cellular network does not support transferring the packet switched audio stream to the legacy cellular network.

14. A non-transitory computer readable storage medium having computer program code stored thereon, the computer program code comprising program code, which, when executed by one or more processors implemented on a wireless communication device, is configured to cause the wireless communication device to perform a method comprising:

participating in a video call with a remote communication device via a first video call session established over a connection between the wireless communication device and a first cellular network;

determining a degradation in connection quality of the first cellular network;

transitioning to a second cellular network by at least dropping the connection between the wireless communication device and the first cellular network and without invoking a network coordinated handover, in response to the degradation in connection quality of the first cellular network;

establishing a second video call session with the remote communication device on the second cellular network in response to transitioning to the second cellular network;

providing an indication, via a user interface of the wireless communication device, that the video call with the remote communication device is ongoing while transitioning to the second cellular network and establishing the second video call session; and

using the second video call session to continue the video call with the remote communication device on the second cellular network.

15. The non-transitory computer readable storage medium of claim 14 , wherein the first video call session comprises a packet switched video stream carried over a first bearer and a packet switched audio stream carried over a second bearer, and wherein the second cellular network is a legacy cellular network having a circuit switched domain.

16. The non-transitory computer readable storage medium of claim 15 , wherein the first cellular network is a Long Term Evolution (LTE) network, and wherein the second bearer is a voice over LTE (VoLTE) bearer.

17. The non-transitory computer readable storage medium of claim 14 , wherein:

the first cellular network is a Long Term Evolution (LTE) network supporting voice over LTE (VoLTE);

the first video call session comprises a packet switched video stream carried over a first bearer and a VoLTE audio stream carried over a second bearer; and

the second cellular network is an LTE network that does not support VoLTE.

18. The non-transitory computer readable storage medium of claim 14 , wherein the method further comprises:

sending an indication to the remote communication device that the wireless communication device is transitioning between networks prior to transitioning to the second cellular network.

19. The non-transitory computer readable storage medium of claim 14 , wherein the method further comprises:

setting a timer in response to the degradation in connection quality of the first cellular network; and

providing an indication via the user interface that the video call with the remote communication device has been dropped in an instance in which the second video call session is not established prior to expiry of the timer.

20. The non-transitory computer readable storage medium of claim 14 , wherein determining the degradation in connection quality of the first cellular network comprises determining that a measured connection quality of the first cellular network is less than a threshold connection quality.