Endurance II
I think the Echolink would be way to have it. Its free and easy to set up. You do have to have your license so members thinking of becoming hams would not be able to attend the "conference". But its the only way to get all the formats together that would be out in Ham Radio. Also could connect when traveling or out of range from repeater. I have it set up on android phone and laptop and works great. My 2 cents Brent KJ7BHN