CTI application 3-d party for PBX Panasonic KX-TD/KX-TDA, which allows to display the number of calling subscribe on EXT line or number dialed from it.Calling number at an incoming call from an extension line is determined by PBX under condition that CallerID function for analog outside lines, CLIP or ANI for digital outside lines and appropriate complete sets and settings of the PBX are given by the connection operator.