The invention relates to a method for processing the parameters of a speech coder according to the quality of the transmission connection. The quality of the transmission connection is determined in a quality monitoring member (409) on the basis of erroneous/error-free classifications of single received frames so that for determining the quality of the transmission connection the classifications of single frames performed during several subsequent speech frames are scanned. On the basis of the quality of the transmission connection both the replacement procedure of erroneous speech frames carried out in the replacement member (402) and the processing of the frames detected as error-free carried out in the processing member (406) of error-free frames are controlled so that the effect of the transmission errors on the quality of the decoded speech signal remains insignificant.