We tested with CVP warm transfer, when CVP passes call to agent, agent transfers to second CVP for queuing. This scenario works when agent uses single-step transfer, the caller can hear queuing messages. However if 'consult transfer', the caller hears nothing, and call drops in a few seconds.
We can see the call hits the second CVP and VXML gateway, so teh signaling path is ok, it fails in establishing media path.
If we do a direct call to agent, then warm transfer to second CVP, it works, so I don't think IP phone configuration is issue. So the problem seems in CVP.
Does nayone have clue for this type of issue?