Speakfreely is "in the public domain"and is absolutely free.
( http://www.gnu.org/directory/telephony/SpeakFreely.html ).
Furthermore Speak Freely is a free -cross platform- Internet telephone which provides high quality audio, military grade encryption, and interoperability with Speak Freely for Unix,windows and other RTP-compliant applications.

The actual homepage is http://speak-freely.sourceforge.net/ .