http://www.gnu.org/software/sipwitch/ "GNU SIP Witch can be used to build secure and intercept-free telephone systems that can operate over the public Internet." ---------- Forwarded message ---------- From: S Date: Mon, Aug 22, 2011 at 1:58 AM Subject: GNU Free Call: An Open Source Skype Alternative To: http://www.pcworld.com/businesscenter/article/222556/gnu_free_call_an_open_s... *The SIP Protocol* To make all that possible, GNU Free Call will use the Session Initiation Protocol <http://en.wikipedia.org/wiki/Session_Initiation_Protocol> (SIP), an Application Layer signaling protocol that's designed to be independent of the underlying transport layer. Specifically, it will build upon the existing GNU SIP Witch<http://www.gnu.org/software/sipwitch/>VoIP server, which operates without introducing a central point through which communications can be intercepted or captured. GNU SIP Witch also requires minimal system resources, making it suitable even for low-end embedded routers. GNU SIP Witch is already packaged in a number of popular Linux distributions, including Ubuntu<http://www.pcworld.com/businesscenter/article/221517/work_begins_on_ubuntu_1110_oneiric_ocelot.html>and Fedora, but it can also be built on most BSD systems from source, and it supports compilation on Microsoft Windows<http://www.pcworld.com/businesscenter/article/207196/why_windows_is_bad_for_business.html>as well, according to the GNU Free Call project. "We will extend SIP Witch to become aware of peer nodes by supporting host caches, and then support publishing of routes to connected peers," the project explains. Host caches are a mechanism used in older P2P networks and are easy to implement, it adds.