The benefits of Zencastr's built in VoIP is that it is simpler for everyone to not have multiple programs to worry about. Zencastr can also apply some echo cancellation if it is handling the VoIP stream. Only the host needs an account. Anyone can join the call and use the VoIP. Most people who use Skype alongside Zencastr do so because they want video as well as audio, or they want to continue to run a Skype Call Recorder as a backup recording.