Attempting to stop mic audio from flowing to SIP server

gistfile1.txt

          onlocalstream : function(stream)
          {
            console.log("SIP: attaching local stream");

            // Initially mute the microphone
            var tracks = stream.getAudioTracks();
            tracks.forEach(
              function(track)
              {
                console.warn("SIP: before enabled=false: track=", track);
                track.enabled = false;
                console.warn("SIP: after enabled=false: track=", track);
              });

            setTimeout(
              function()
              {
                console.warn("SIP: stopping audio track");
                tracks[0].stop();
              }, 5000);
          },