The ANS3000 allows you to have "Call Screening" - - meaning that you can listen to the caller as they are leaving their message. You will hear the caller's message at whatever volume level you have previously selected (from 0 - - -no sound to 10 - - the loudest level of volume). All you need to do to screen a call is be close enough to the ANS3000 to hear the caller as they are leaving their message. If you decide you would like to speak to the caller, just pick up the handset on the phone that is attached to the ANS3000.
If you have selected a volume level of "0" - no sound, this means you have turned off your ability to listen to the calls as the caller is leaving the message. You will also not be able to listen to the recorded messages until you increase the volume to at least level "01."
If you want to use Call Screening, be sure you have selected a volume level of at least "01."