If you cannot hear the other participant(s), make sure your loudspeakers or headphones are connected. Then check all volume controls:
Your headphones or loudspeakers may have their own volume buttons or switches.
The Windows/Mac OS X volume settings override all other volume controls. (Windows) Look for the loudspeaker icon in your system tray to open and/or unmute. (Mac) Check the volume indicator on the menu bar or go to System Preferences > Sound.
Cisco Jabber Video has its own volume setting on the [x-ref] Using the pop-up toolbar [p.8].
If this does not solve the problem, it may be that audio is not being sent from the other end. Ask the other participant(s) to perform the microphone check described below.
Others cannot hear you
If the other call participant(s) cannot hear you, make sure your microphone is properly connected and not muted.
Low or distorted sound
If call participants are experiencing distorted sound, very low sound, or echos:
Check whether any of you have enabled microphone boost, echo cancellation, gain control, noise reduction, digital effects, or similar features for your audio devices.
Turn all such audio device features off for Jabber Video to work optimally.