Can you explain why you feel RSVP does not provide real control? Do you feel that current Dif Serv mechanisms help at all?
While I somewhat agree that gateways do not provide the total solution for QoS they provide a part of the solution, after all QoS is an end-to-end story.
Silence surpression seems to give about a 30-50% bandwidth reduction. The reason I say this is becuase in normal conversations not everyone is speaking at once.