[php] Formatting Phone Numbers in PHP

Here's a simple function for formatting phone numbers with 7 to 10 digits in a more European (or Swedish?) manner:

function formatPhone($num) {
    $num = preg_replace('/[^0-9]/', '', $num);
    $len = strlen($num);

    if($len == 7) $num = preg_replace('/([0-9]{2})([0-9]{2})([0-9]{3})/', '$1 $2 $3', $num);
    elseif($len == 8) $num = preg_replace('/([0-9]{3})([0-9]{2})([0-9]{3})/', '$1 - $2 $3', $num);
    elseif($len == 9) $num = preg_replace('/([0-9]{3})([0-9]{2})([0-9]{2})([0-9]{2})/', '$1 - $2 $3 $4', $num);
    elseif($len == 10) $num = preg_replace('/([0-9]{3})([0-9]{2})([0-9]{2})([0-9]{3})/', '$1 - $2 $3 $4', $num);

    return $num;
}