A method operates a system of a hearing aid device and a communication device. The hearing aid device has an acousto-electrical transducer, a signal processing device and an electro-acoustic transducer. The communication device has a controller and an electro-acoustic transducer. The method includes the steps of: receiving of an incoming call by the communication device, signaling of the incoming call by the communication device by a first acoustic signal via the electro-acoustic transducer, receiving of the first acoustic signal by the acousto-electrical transducer of the hearing aid device, identifying of the first acoustic signal and carrying out of a first change of adjustment on the hearing aid device when the first acoustic signal has been identified.