The invention relates to method of processing a speech frame in radio system, a radio system, a mobile station in radio system, and a network of radio system. In the method a speech frame having propagated over a radio path is channel-decoded. If on the basis of the channel-decoding the speech frame is free of defects, it is inferred from the value of at least one speech parameter in the channel-decoded speech frame whether the speech frame contains speech that is decodable by means of a speech decoder; and if, according to the inference, the speech frame does contain speech that is decodable by means of a speech decoder, the speech frame is decoded by means of a speech decoder; and if, according to the inference, the speech frame does not contain speech that would be decodable by means of the speech decoder, the speech frame is not decoded.