If you're having issues with your audio please try the following:

• Check the audio settings on your device to ensure that the correct input/output channels are selected and that the volumes is on.
• Check that the browser has permission to access your microphone.
• Chrome is the recommended browser however COS is compatible with Firefox and Opera.
• Completely log out of the COS dialer, close/quit your browser and log back in. 
• Ensure that your headset is plugged in properly.
• If using a wireless headset ensure that the bluetooth connection is enabled. 

If you are still experiencing issues please contact COS support.