As was noted before, you do need a good quality line. Not so much a fast line
(I think that even something like 300Kbps, in both directions, effective capacity would be fine).
But the line has to be "clean" so that you don't experience excessive packet loss.
I have setup a remote Obi in Europe (Greece) and another one in the US.
The voice quality is consistently very good.
In terms of calls to India, I have noticed (as the previous responder mentioned) issues.
Part of the problem is that some standard DSL services are providing 256Kbps uplink.
But even more problematic was that some times there were packet losses. So, the quality would
vary by the day. But I wouldn't attribute the problem to the Obi itself. There is
little the Obi can do if the network drops pkts left and right.
EDIT: In both setups I meant to say that all calls are Obi-to-Obi over the Obitalk network.
L.