code: function createdDescriptionCallback(description)
      {
          scope._conn.setLocalDescription(description)
          .then(function()
          {
              if(scope.onDescription)
              {
                  scope.onDescription(scope,JSON.stringify({'sdp': scope._conn.localDescription}));
              }
          })
          .catch(onErrorCallback);
      }
docs: sdp offer/answer description callback