foreach my $File (@Files) {
    next unless -e $File;  # already deleted
    my($type, $basename) = $File =~ /^PBX-(INTERNAL|IN|OUT)-(.*)\.wav$/;
    if(!$type) {
        # ???
        unlink $File;
    }
    elsif($type ne 'INTERNAL') {  # IN, OUT
        system("/usr/bin/sox -m $File PBX-INTERNAL-$basename.wav $basename.wav");
        unlink $File, "PBX-INTERNAL-$basename.wav";  # delete originals
        system("/usr/bin/lame --cbr -b 32 --noreplaygain -q 2 \"$basename.wav\" \"$basename.mp3\" --quiet");
        if(!$? && -e "$basename.mp3") {
            system("mv \"$basename.mp3\" $mount");
            unlink "$basename.wav";
        }
    }
}