VoIP Server
From forum post https://www.clearos.com/clearfoundation/social/community/what-features-or-changes-would-you-like-to-see-around-here#reply-250921
Developer comment:
WikiSuite had this on their ToDo feature list and got part way through programming in 2017. There is a Beta of Freeswitch in contribs-testing but it is not production quality.