The intrusive speech quality model standardized by the ITU-T shows some limits in its quality predictions, especially in a wideband transmission context. They are mainly caused by strong differences in perceived quality when speech is transmitted over different telephone networks. Instrumental methods should provide reliable estimations of the integral speech quality over the entire perceptual speech quality space. This paper presents a new model, called Diagnostic Instrumental Assessment of Listening quality (DIAL). It combines a core model, four dimension estimators and a cognitive model, providing integral quality estimations.