VoIP - Conference Calls
Whilst not a feature on the server side, conferencing multiple calls together is possible on many VoIP phones. E.g., the Snom series has a 'conference' button which enables multiple calls to be joined together. Please see the documentation for your phone regarding this.
Other VoIP Features
<ncl style=bullet maxdepth=5 headings=bullet headstart=2 showcats=1 showarts=1>Category:VoIP Features</ncl>