Abstract: A method for transmitting a message by ambient scattering. The method is implemented by a transmitting device in response to the transmitting device changing from a first state in which the transmitting device is deprived from illumination to a second state in which the transmitting device is illuminated by at least one light source. The method includes: obtaining an amount of electrical energy stored from light energy; comparing the amount of electrical energy stored with a given threshold, the threshold representing an electrical energy quantity sufficient to allow transmission of a message by ambient scattering; and in response to the threshold being overrun, transmitting a message called “information message”, representative of the threshold overrun, the transmission being implemented by using the stored electrical energy.