This article explains how to set up and record a Google Voice conference call.
Conference calls
Setting up and managing a Google Voice conference call is easy. You don’t have to start as a conference, as you can convert one-on-one conversations to conference calls if needed. Your Google Voice number can also be combined with Google Chat to get the full conference effect.
Inform conference attendees that they can call you at an agreed-upon time on your Google Voice number.
Make a phone call to one of the participants by having them call you or by calling yourself using Google Voice.