Green/yellow LED means the Null connector is active:
http://manuals.sharkrf.com/openspot2/en/led-states.html
The Null connector - as it's name says - does not connect to a server. What you have to do is to open the web interface and use the Quick Setup to connect the openSPOT2 to a server.
You should test your own voice / BER using the openSPOT2's local echo service.
http://manuals.sharkrf.com/openspot2/en/control-calls.html
What kind of transceiver do you have?