:www.openh323.org
有协议栈,软终端(openphone,ohphone),以及opengk,openmcu.....
http://www.voxgratia.org/documents.html
Open G.729(A)
http://www.vovida.org/applications/downloads/G729A/#Source_Code
SIP,mgcp开放源代码:
www.vovida.com
voip的协议标准文档:
http://www.packetizer.com/
http://standard.pictel.com/ftp/avc-site/
http://www.voxgratia.org/
其它的大家补充.