IP Audio pass the Mic, similar to Centra - Text Chat Questions, Test questions with histogram, archive report has answers by student. 250 concurrent users Max. Firewall can be configured, with separate port 7000. URL push - Live web page. Users can browse, until the presenter changes the page.
Interface is fairly clean, somewhat confusing.
App Sharing is a bit difficult because it uses peer to peer. 1 year minimum contract. Users must have an account on the server, difficult entry for that reason. US Cost Guard uses this solution. Meeting Train is a hosted solution.