mp3tonative.sh:

FROMDIR="/var/lib/asterisk/mp3s"
TODIR="/var/lib/asterisk/transcodes"
for i in $FROMDIR/*.mp3
do
BASEFILE=$(basename "$i")
echo ---------------------------------------------------
echo Converting MP3 file $BASEFILE
mpg123 -s --rate 44100 --mono "$FROMDIR/$BASEFILE" > "$TODIR/$BASEFILE.raw"
sox -r 44100 -w -s -c 1 "$TODIR/$BASEFILE.raw" -r 8000 -c 1 "$TODIR/$BASEFILE.wav"
sox "$TODIR/$BASEFILE.wav" -t gsm -r 8000 -b -c 1 "$TODIR/$BASEFILE.gsm"
sox "$TODIR/$BASEFILE.wav" -t ul -r 8000 -b -c 1 "$TODIR/$BASEFILE.pcm"
rm -f "$TODIR/$BASEFILE.raw"
echo ---------------------------------------------------
done