PC to PC calling and videoconferencing made easy
Ekiga (formely known as GnomeMeeting) is an open source VoIP and video conferencing application for GNOME. It allows you to simply conduct PC to PC calls and videoconferences.
Ekiga uses both the H.323 and SIP protocols. It supports many audio and video codecs, and is interoperable with other SIP compliant software and also with Microsoft NetMeeting.