A communications system and a method of detecting and learning new ringtones in an automatic manner, comprising a desk phone (1), a hook switch, a ringtone detector (3), and a communications device (2). In a first embodiment a mechanical hook switch device is connected to the desk phone (1), and in a second embodiment an electronic hook switch unit (9) is connected to the desk phone (1). The ringtone detector (3) adaptively sets the filter and amplifier parameters according to the sensor position and pick-up sensitivity. The ringtone detector (3) automatically detects and learns the characteristics of new ringtones. The communications device (2) may comprise a base station (6) and a headset (7).