Discord is a brand new and pretty fantastic voice chat system. It is available for PC, Mac, iOS, Android and as a web version, and its pretty simple to set up.
Just click on the connect button in the bottom of the chat window on the other side of this page, or click here, and you will be wisked away to the discord site which will ask you if you want to accept the invitation (Just like if you're asked if you're a god, you. say. YES).
You will then setup an account and then you will be ported over to the web version of our chat room.
From there, at the bottom of the left side of the page you're going to want to click on download apps and install the appropriate desktop version for your computer. Run through the install and sign in with your account info.
Once you're signed in, you should see in the very left column, the guild logo for the SD chat room, click on that to join. Then, at the bottom left by your username & avatar if you set one up, click the cog wheel for settings.
Go to voice and make sure your input and output devices are set correctly and make sure you change the input mode to push to talk.
You should now be all set. And remember, its best to get this set up and tested BEFORE raid call!