Actually, there's an open case on this - it's being investigated.
When you stream to your microphone it goes straight from Exchange to your client's machine as a stream, no problem.
When you use TRAP, however, it SHOULD stream from Exchange to Unity to your phone. But what's happening now is it streams from Exchane to your client to Unity and then to your phone. There appears to be a problem with the direct connect from Unity to Exchange in this case and it falls back on the client hop for some odd reason. This is being worked on...
