The document describes research using genetic programming to develop models for real-time, non-intrusive evaluation of VoIP quality. Researchers collected data on VoIP traffic parameters and quality ratings to train and test models. The best models estimate quality as a function of bitrate, loss rate, frame duration, and other variables. The models perform comparably to PESQ, the standard quality estimation method, and better than prior approaches, allowing real-time quality monitoring without intrusive measurement.