What is the highest acceptable latency to attempt a VoIP call over? Is that one way or round trip? Would 230ms...
one way be workable?
There is a good discussion on VoIP and delay at the following link: http://commsdesign.com/design_corner/OEG20021016S0005.
The indication is that the speech overlap can become a problem if the one way delay is greater than 250 ms. Whether or not the latency is 'acceptable' will depend on the calling and called party. Over some satellite connections the one way delay can be much longer than 250 ms one way but this is accepted by the people using the service.