In this paper, we propose an efficient rate selection algorithm that can be used to transcode speech encoded by any code excited linear prediction (CELP)-type codec into a format compatible with selectable mode vocoder (SMV) via direct parameter transformation. The proposed algorithm performs rate selection using the CELP parameters. Simulation results show that while maintaining similar overall bit-rate compared to the rate selection algorithm of SMV, the proposed algorithm requires less computational load than that of SMV and does not degrade the quality of the transcoded speech.