In the introduction of this paper, we present a background on SDR, in section 2, we give a quick demonstration of main GSM features and ways to improve QoS in it. After a short recognition of key fading effects in section 3, we analyze in section 4 the Soft Output Viterbi Algorithm used to perform equalization tasks in GSM. In sections 5 and 6, we use simulation results to effectively categorize variable parameters of the flexible equalizer upon user defined level of QoS. We show also the importance of such approach in effectively utilizing hardware resources dedicated for performing digital signal processing tasks, and in reducing power consumption required for these tasks.