New Post: Problem Converting To GSM610

here you go

using (WaveFileReader reader = new WaveFileReader(Input))
            {
                using (WaveFormatConversionStream Conveter = new WaveFormatConversionStream(WaveFormat.CreateCustomFormat(WaveFormatEncoding.Gsm610, 8000,
                    1, 16000, 2, 16), reader))
                {
                    WaveFileWriter.CreateWaveFile(Output, Conveter);
                }
            }