public static function isViablePhoneNumber($number)
    {
        if (static::$VALID_PHONE_NUMBER_PATTERN === null) {
            static::initValidPhoneNumberPatterns();
        }

        if (mb_strlen($number) < static::MIN_LENGTH_FOR_NSN) {
            return false;
        }

        $validPhoneNumberPattern = static::getValidPhoneNumberPattern();

        $m = preg_match($validPhoneNumberPattern, $number);
        return $m > 0;
    }