A method for in-service monitoring of the end-user perceptual speech quality in modern cellular radio systems is proposed. This method incorporates the perceptual evaluation of speech quality (PESQ) algorithm to monitor the quality experienced by the end-user. Here, the monitoring is carried out at the transmitting side. In this case, the speech signal received by the end-user is approximated at the transmitter in accordance with a feedback signal. The performance of the proposed scheme has been investigated through extensive computer simulations for the Universal Mobile Telecommunication System (UMTS) using different speech coding rates and channel conditions. The results indicate that the proposed scheme can predict the end-user quality with a root-mean-squared error (RMSE) of at most 0.15 using the mean opinion score (MOS) rating scheme. Such accuracy can be beneficial in applications such as network maintenance and radio resource management for satisfying desired level of quality of service.