The official home page of Ekiga is http://www.ekiga.org/. This site offers the frequently asked questions as well as a more detailed documentation.
For information about the support of the H323
teleconferencing protocol in Linux, see http://www.voip-info.org/wiki/view/H.323. This is also a good starting point
when searching for projects supporting VoIP.
If you intend to set up your private telephone network, you might be
interested in the PBX
software Asterisk http://www.asterisk.org/. Information about this project can
also be found at http://www.voip-info.org/wiki-Asterisk.