Question: In a congested E-UTRAN network, how does a User Equipment (UE) handle an ongoing MMTEL voice/video call when it receives an RRC Connection Release message with redirection?
Option 1: The UE terminates the call and attempts to re-establish it after re-accessing the network.
Option 2: The UE maintains the call at the application layer during the redirect procedure, allowing for immediate recovery of the voice GBR (Guaranteed Bit Rate) bearer post re-access.
Option 3: The UE switches the ongoing call to a non-GBR bearer to reduce network load before re-accessing.
Option 4: The UE prioritizes MMTEL video over voice calls during the redirection, potentially dropping voice calls.
Explanation: This is correct because, during the redirect procedure for a congested network, if a UE receives an RRC Connection Release message with redirection while a voice/video call is ongoing, it keeps the call active at the application layer. This allows for seamless continuation of the service by immediately recovering the dedicated voice GBR bearer once the UE successfully re-accesses the network, thus minimizing service interruption.