An apparatus for identifying a communications signal in a preceding stage for a communications modem includes a communications signal identifying unit configured to receive a communications signal through a port, deliver data included in the communications signal to a communications modem, and sample the communications signal which has passed through the port during every unit length to detect a unit length pattern corresponding to a start of communication and a unit length pattern corresponding to an end of communication. When a length from the start of communication to the end of communication is equal to or smaller than a reference length, the communications signal identifying unit delivers a data process stopping signal to the communications modem such that the communications modem stops a data reading operation.