Javecho is a free and open-source application that will provide you with a VOIP interface to the soundcard on your computer. It's primary purpose is to interface with the EchoLink system.
Javecho is an EchoLink client written in the Java programming language. The user interface is very similar to the standard Windows based Echolink software. This should help people familiar with the operations of the Windows version of EchoLink use Javecho.
Javecho does not support the Sysop mode yet, so it can't let you control your radio. Give Javecho a try to see what it's all about!