RAT is a network audio tool that allows users to particpate in
audio conferences over the internet. These can be between two
participants directly, or between a group of participants on a
common multicast group.  RAT features sender based loss mitigation
mechanisms and receiver based audio repair techniques to compensate
for packet loss, and load adaption in response to host performance.

WWW: http://www-mice.cs.ucl.ac.uk/multimedia/software/rat/