Disclosed is a method of inhibiting the binding of a cell bearing a cell adhesion protein to a molecule or cell bearing a carbohydrate determinant specific for the cell adhesion molecule. The optical touch panel includes a processing unit, and at least three optical detectors divided into at least two detector groups. The audible advertisement is played on the communication device to the caller prior to initiating a connection to a callee. The light guide has a circular cone shape and has a cross-sectional area that decreases in a direction from the entering portion to the exiting portion.