The S1T2418G01/D02 is a monolithic integrated circuit telephone tone ringer with bridge diode. When coupled with an appropriate transducer, it replaces the electro-mechanical bell. This device is designed for use with either a piezo transducer or an inexpensive transformer-coupled speaker to produce a pleasing tone composed of high frequencies (fH1, fH2) alternating with a low frequency (fS) resulting in a warble frequency. The supply voltage is obtained from the AC ring signal and the circuit is designed so that noise on the line or variation of the ringing signal cannot affect correct operation of the device.