A method for branching data in a mobile communication terminal to perform data communication between a mobile station and a network which have media access control sublayers. The heating device comprises a plurality of PTC heating elements arranged in a plane of said heating device. Vias that contact the thin-film resistor from below are formed in the second interlayer insulating film. A second boundary, which is typically a boundary button is oriented above and generally parallel with the microphone element creating an overall improvement in frequency response.