I can join a hangout but when I try to join the video/audio it says I've been disconnected from the server and make sure I have an internet connection. I am trying this over 3G however I can access the internet just fine from my phone. Plus I can join the hangout to start with.
Restarting phone made no difference.
I haven't tested on wifi as none is available atm, plus I want it on 3G anyway.