It is similar but not identical to a system I used to use for testing the volume of telephone ringers. It will work to provide ringer voltage but probably produce much higher voltage than you need. If I remember right, the system I used had a pair of bipolar transistors instead of MOSFETs but that make little difference, it used an 18-0-18 transformer though so the output voltage was much lower. The danger of producing 230V is most phones, even old ones, had a voltage clamping circuit in them which will effectively short out any excess voltage and overload your circuit.
Brian.