It should be open, but we have a 512 person TS3** server at the event.
**Disclaimer: I do not work for any company that deals in VoIP technology, but I have a DEEP hatred for Ventrilo's Licensing bullCrap. You can run your own little 8 person... But if you want more you have to rent from a company. So I thought at one point we could get our act together and purchase a license... NO! You have to buy at LEAST 1000 seats and PROMISE to buy MORE every year!
Not to mention that Teamspeak 3 is a superior product.