SIP Witch

SIP Witch


GNU SIP Witch is a secure peer-to-peer VoIP server that uses the SIP protocol. Calls can be made peer-to-peer behind NAT firewalls, and without needing a service provider. GNU SIP Witch supports using secure telephone extensions, for placing and receiving calls directly over the Internet, and intercept-free peer-to-peer audio and video extensions. GNU SIP Witch also is being introduced as a desktop VoIP mediation service to enable the construction of participatory bottom-up secure calling networks and to enable replacement of Skype with free software and published protocols. As a desktop mediation service, GNU SIP Witch can solve issues like NAT in one place for all user agents, and offer new ways to route and redirect VoIP much like gstreamer does for desktop media.

GNU Bayonne is the telephony server of GNU Telephony and the GNU Project. The production release of GNU Bayonne 1 is 1.2.15 and has a long history in production telecommunication environments. GNU Bayonne supports IVR scripting using hardware from Voicetronix, Dialogic, Aculab, CAPI drivers, and Quicklink drivers under GNU/Linux. GNU Bayonne 1 can integrate perl and python applications, and has been commercially deployed in production use for several years. Future releases of GNU Bayonne will be based on ucommon and will further explore it’s role as a Telephony integration server.

GNU SIP Witch is a call and registration server for the SIP protocol. As a call server it services call registration for SIP devices and destination routing through SIP gateways. GNU SIP Witch does not perform codec operations or media proxying and thereby enables SIP endpoints to directly peer negotiate call setting and process peer to peer media streaming even when when multiple SIP Witch call nodes at multiple locations are involved. This means GNU SIP Witch operates without introducing additional media latency or offering a central point for media capture.

GNU SIP Witch is designed to support network scaling of telephony services, rather than the heavily compute-bound solutions we find in use today. This means a call node has a local authentication/registration database, and this will be mirrored, so that any active call node in a cluster will be able to accept and service a call. This allows for the possibility of live failover support in the future as well.

GNU SIP Witch is not a SIP “router”, and does not try to address the same things as a project like iptel “Ser”. GNU SIP Witch is being designed to create on-premise SIP telephone systems, telecenter servers, and Internet hosted SIP telephone systems. One important feature will include use of URI routing to support direct peer to peer calls between service domains over the public internet without needing mediation of an intermediary “service provider” so that people can publish and call sip: uri’s unconstrained. GNU SIP Witch is about freedom to communicate and the removal of artifical barriers and constraints whether imposed by monopoly service providers or by governments.

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