When we start the shutdown sequence for a channel, there is no need to submit any RTP packets that are queued on the command list. Under extreme load with many backed up RTP packets it was possible to have RTP packets submitted after the channel shutdown process started. Signed-off-by: Shaun Ruffell <sruffell@digium.com> Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>