In current communication systems, forward Error Correction (FEC) codes are used to decrease the information losses in the transmission channel to improve the signal quality in the reception point. The speech quality is affected by many factors being packet losses one of the most important. Currently, there are different speech quality assessment methods; for planning purposes, E-model algorithm is the most representative. However, it does not consider wireless network characteristics and techniques. Based on this fact, the main contribution of this work is to adapt the wide-band (WB) E-model algorithm to be able to evaluate the impact of FEC codes on speech quality. For this purpose, a function named GFECx(Ms,SNR) is proposed that quantifies the quality gain reached by FEC codes at different wireless channel conditions. This function is inserted into Ie,eff,WB impairment factor of the WB E-model algorithm. Experimental results demonstrated that the proposed solution gets a high correlation with results obtained by ITU-T Rec. P.863, reaching an average PCC and RMSE of 0.990 and 2.629, respectively. Thus, the methodology introduced in this research makes it possible to estimate the speech quality when FEC codes are implemented in a communication system.