Ventrilo is a well known restrictive freeware Voice Over IP or in short VoIP program. It runs on Microsoft and Mac operating systems. Ventrilo users connect to each other using microphones or headsets through Ventrilo servers.

The VoIP system was launched on 3rd August 2002 and could be run on Microsoft OS only, however later it was developed to be run on Mac OS as well. Currently, Ventrilo servers can be used on Solaris, NetBSD, and FreeBSD in addition to Microsoft and Mac OS.

The use of the freeware version of Ventrilo servers is restricted to only 8 users. A pro version of Ventrilo servers is although available to be used by more than 8 users by paying a certain monthly charge.