TECHNIQUES FOR PACKET-SWITCHED VIDEO TELEPHONY SETUP WITH QOS PRECONDITIONS

摘要

Techniques for setting up a packet-switched video telephony (PSVT) call are described. A mobile originated (MO) device may transmit an invitation for the PSVT call to a mobile terminated (MT) device. The invitation may initiate a process to reserve and identify video and audio resources to establish the PSVT call. The MO device may determine whether the video resources are available. If the video resources are not available but audio resources are available, the MO device may instead establish the PSVT call with only an audio stream call between the MO device and the MT device. If audio resources become available ahead of video resources, the PSVT call may be established with an audio stream first and a video stream is automatically added to the call when video resources are reserved later, or the PSVT call is downgraded to a VoIP call if the video resources cannot be reserved.