Robust Audio Tool (RAT) 

The Robust Audio Tool (RAT) is a an open-source audio conferencing and
streaming application 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 is capable of encrypting voice traffic using TripleDES.  Users
at each end of a conversation are prompted to enter a passphrase
to begin an encrypted conversation.

The RAT Homepage is located at:

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