This is not exactly fixed. I am running build 2286 and still seeing a similar anomaly. I do not want to use Call transfer at all so I have the box "Transfer enabled" un-checked. However, when I try to do a conference call I get similar results to your original tests with call waiting. I don't always get the same result, though sometimes I just get disconnected when I press flash. In any case, after some trial and error I discovered that the Obi always bridges the call when I hang up, even with the "call transfer enabled" box un-checked. With Callcentric this causes issues because they charge you for call #2 as long as the Obi keeps the call bridged, even if the line has gone dead for the callee. I found a work around by checking the box "UseRefer". Callcentric does not allow this so as soon as I hang up and the Obi tries to transfer, call #2 is dropped and I get the ring on my phone telling me call #1 is on hold. Sort of a fix, but the Obi shouldn't bridge the lines if Call transfer is clear. If I hang up it should simply drop both calls.