GNU SIP Witch provides a secure peer-to-peer VoIP server for the SIP protocol and part of the GNU Project. As a pure SIP mediation service, SIP Witch offers low latency and direct peer-to-peer connection between user agents. SIP Witch can be used as part of the desktop software stack offering VoIP mediation service to create bottom-up secure calling networks and, in combination with a ZRTP enabled SIP user agent, as a free software alternative to Skype. SIP Witch can also be used as a traditional stand-alone SIP-based office telephone server, or as a secure VoIP domain call manager inter-operating with an existing insecure IP-PBX.

Official website

Mailing Lists

Latest Releases

  • Source distributions of sipwitch can be downloaded from the GNU Project.
  • Packaged sources for building binary packages for redhat and debian GNU/Linux can be downloaded from GNU Telephony.

Bug Tracker

Latest News

GNU SIP Witch 0.7 offers introduction of NAT mediation services. GNU SIP Witch 0.5 introduced a concept of internodal calling and allows sipwitch to transform itself into a sip redirection server for specific local destinations. Internodal calling differs from dialing to remote uri's in that the authentication record is pre-stuffed into the remote invite, hence, all nodes must share the same sip realm. This allows one sipwitch server to call a "local" extension number that actually appears on a remote switch rather than the one the user agent is registered to. The forward secure calling domain plugin also makes use of internodal calling to connect with the insecure calling domain.

Supported Platforms

GNU SIP Witch works with all modern distributions of GNU/Linux. The source can also be built and run on OpenSolaris, OS/X, NetBSD, OpenBSD, and FreeBSD. Support exists for building sipwitch for use on Microsoft Windows using mingw32. The server can also be built and operate in deeply embedded and flash-boot environments, including uclinux based targets.


GNU SIP Witch is licensed with the GNU General Public License, version 3 or later.

Related Projects

  • Bayonne - multi-protocol telephony application server of the GNU Project.
  • Secure Call - GNU Telephony Secure Call Project.


  • Build tools: automake, gcc, libtool
  • Required libraries: ucommon, exosip2, osip
  • Optional Libraries: avahi, openssl, gcrypt

Created by: dyfet, Last modification: Thu 25 of Mar, 2010 (22:33 UTC)
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