An image processing apparatus that covers standards of a dial tone for a plurality of countries with a relatively small number of pattern tables and reduces the number of times that a sound is misdetected as a dial tone, a method for controlling the same and a program are provided. To accomplish this, the image processing apparatus measures a length of a tone signal received from outside; determines whether an intermittent dial tone including the measured tone signal and a previously received tone signal has a specific pattern or not; and determines whether a duty cycle of the intermittent dial tone is a duty cycle within a given range or not, thereby determining whether the dial tone is valid or not.