Ekiga – Open Source VoIP Service

Open Source VoIP Client for Windows & Linux

Ekiga is an open-source VoIP service that is compatible with Windows and Linux. Ekiga allows you to make voice and video phone calls and to send text messages to cell phones. It also enables standard telephony features like call holding, call forwarding and dial tone.
Ekiga supports a common VoIP protocol called session interface protocol and offers you a free SIP address during registration. You can configure multiple SIP addresses through the client and use those addresses simultaneously. Ekiga does not support encryption.

QuteCom - Open Source Softphone

Open Source Communication Software

QuteCom is a SIP compliant software. VoIP client developed by the QuteCom (previously OpenWengo) community under the GNU General Public License (GPL). It allows users to speak to other users of SIP compliant VoIP software at no cost. It also allows users to call landlines and cell phones, send SMS and make video calls. QuteCom is an free and open source voice-over-ip, and video conferencing application. The latest version of the software is always available on the QuteCom website.

QuteCom 2.2 is licensed under the GPL, and is free software.

Banshee - Open Source Music Player

Play your music and videos. Keep up with your podcasts and Internet radio. Discover new music and podcasts. Keep your portable device loaded with good stuff.
Banshee is a cross-platform open-source media player, called Sonance until 2005. This open source music player uses the GStreamer multimedia platform for encoding and decoding various media formats, including Ogg Vorbis, MP3 and FLAC.

Exim - Open Source message transfer agent

Exim is a message transfer agent (MTA) developed for use on Unix systems connected to the Internet. It is freely available under the terms of the GNU General Public Licence. In style it is similar to Smail 3, but its facilities are more general. There is a great deal of flexibility in the way mail can be routed, and there are extensive facilities for checking incoming mail. Exim can be installed in place of Sendmail, although the configuration of Exim is quite different.