A device for transforming a digital signal into an acoustic signal, making use of a standard phase modulation, that comprises a modem chip (1) with a phase modulation of known kind, used until now for the data transmission via cable, conceived and used only for a cable connection, for acquiring a digital signal through a serial inlet RS232 and for modulating the same according to a standard record V.22, and an acoustic transducer (2) of the piezoelectric kind guided by the modem chip (1).