A mobile device comprising: an ear jack interface for reception of a 4-pole earphone header of an earphone, the ear jack interface including a microphone electrode pin for connection to an earphone microphone terminal of the earphone header; and a control unit configured to: receive at least one input signal through the microphone electrode pin, the input signal being created by earphone input elements (221, 223) of the earphone, identify the received input signal, and control a particular user-function of the mobile device corresponding to the identified input signal, wherein the ear jack interface further includes: an Analog Digital Converter, ADC, having an input connected to the microphone electrode pin; and a comparator for comparing a voltage value output by the ADC with a reference voltage value, and for outputting, to the control unit, a comparison result depending on whether or not the voltage value output by the ADC is lower than the reference voltage value, wherein the control unit is further configured to: identify the voltage value output by the ADC in response to receiving the comparison result that the voltage value is lower than the reference voltage value, and determine types of the input signals created by the earphone input elements (221, 223) according to the identified voltage value output by the ADC. an ear jack interface for reception of a 4-pole earphone header of an earphone, the ear jack interface including a microphone electrode pin for connection to an earphone microphone terminal of the earphone header; and a control unit configured to: receive at least one input signal through the microphone electrode pin, the input signal being created by earphone input elements (221, 223) of the earphone, identify the received input signal, and control a particular user-function of the mobile device corresponding to the identified input signal, receive at least one input signal through the microphone electrode pin, the input signal being created by earphone input elements (221, 223) of the earphone, identify the received input signal, and control a particular user-function of the mobile device corresponding to the identified input signal, wherein the ear jack interface further includes: an Analog Digital Converter, ADC, having an input connected to the microphone electrode pin; and a comparator for comparing a voltage value output by the ADC with a reference voltage value, and for outputting, to the control unit, a comparison result depending on whether or not the voltage value output by the ADC is lower than the reference voltage value, an Analog Digital Converter, ADC, having an input connected to the microphone electrode pin; and a comparator for comparing a voltage value output by the ADC with a reference voltage value, and for outputting, to the control unit, a comparison result depending on whether or not the voltage value output by the ADC is lower than the reference voltage value, wherein the control unit is further configured to: identify the voltage value output by the ADC in response to receiving the comparison result that the voltage value is lower than the reference voltage value, and determine types of the input signals created by the earphone input elements (221, 223) according to the identified voltage value output by the ADC. identify the voltage value output by the ADC in response to receiving the comparison result that the voltage value is lower than the reference voltage value, and determine types of the input signals created by the earphone input elements (221, 223) according to the identified voltage value output by the ADC.