The best replacement for ventrilo is teamspeak.

The best alternatives to ventrilo are rated as following:
★★★★★  teamspeak
★★★★  mumble
★  ts3
★  xfire
★  raidcall
★  teamspeak 3
★  team speak
★  teamspeak 2
  steam voice chat

Your alternative for ventrilo is not listed? Suggest!
Speaking about ventrilo, one probably shouldn't forget about push to talk.

Other search terms related to ventrilo and their ratings are:
★★★★★ push to talk
★ no-ip
You have in mind a companion for ventrilo and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ventrilo in all years. Click on graph for more.
ventrilo
teamspeak
mumble