Voice quality assessment of phone calls is a relevant task for mobile service providers. In this context, the main objective of this research is to provide a model that improves the performance of ITU-T Rec. P.563. To accomplish this objective, the proposed model considers two aspects, better response in lossy network and adequate treatment of silences segments into the audio signal. Thus, a function is determined to suppress silences in the speech signal according to the packet loss rate value. Furthermore, the proposed model is implemented on both a voice quality server and a mobile device. Experimental results show that P.563 algorithm performance was really improved by the proposed model, approximating its results to those given by P.862 algorithm, reaching a Pearson correlation coefficient of 0.9957 and a root mean square error of 0.2983. Moreover, subjective test results demonstrated that the proposed model results overcome those obtained by the P.563 algorithm.