[Freeswitch-users] eavesdrop

I need to enable client to eavesdrop on certain calls. The fs is in a penitentiary institute and certain types of criminals (i..e mafia related) must be listened. I am trying to implement eavesdropping like so: api originate {sip_secure_media=true}user/$ext &eavesdrop($uid) (where, I hope, $ext and $uid are self-explicatory) Is there ANY way to mute the microphone of the eavesdropper? It's a bit of a give-away if the criminal can hear the background noise Thanks Francesco