GNU SIP Witch Telephony Server

GNU SIP Witch is a pure SIP-based office telephone call server that supports generic phone system features like call forwarding, hunt groups and call distribution, call coverage and ring groups, holding, and call transfer, as well as offering SIP specific capabilities such as presence and messaging. It supports secure telephone extensions for making calls over the Internet, and intercept/decrypt-free peer-to-peer audio and video extensions. It is not a SIP proxy, a multi-protocol telephone server, or an IP-PBX, and does not try to emulate Asterisk, FreeSWITCH, or Yate.