SMS pumping and toll fraud: what the numbering plans can stop

Add it at the end of phone.mjs, the file from the JavaScript guide:

// A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB).
export const mayTextTo = (n, countries) =>
  (n.type === 'mobile' || n.type === 'fixedLineOrMobile') && countries.includes(n.region)

// One counter per block of 10,000 numbers: the country code and the national number without its last four digits.
export const rangeKey = (n) => `+${n.cc} ${n.nsn.slice(0, -4)}`

Add it at the end of phone.py, the file from the Python guide:

def may_text_to(number: PhoneNumber, countries: set[str]) -> bool:
    """A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB)."""
    return number.type in ("mobile", "fixedLineOrMobile") and number.region in countries


def range_key(number: PhoneNumber) -> str:
    """One counter per block of 10,000 numbers: the country code and the national number without its last four digits."""
    return f"+{number.cc} {number.nsn[:-4]}"

Add it inside the class in Phone.java, the file from the Java guide:

    /** A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB). */
    public static boolean mayTextTo(PhoneNumber n, List<String> countries) {
        return (n.type().equals("mobile") || n.type().equals("fixedLineOrMobile")) && countries.contains(n.region());
    }

    /** One counter per block of 10,000 numbers: the country code and the national number without its last four digits. */
    public static String rangeKey(PhoneNumber n) {
        return "+" + n.cc() + " " + n.nsn().substring(0, Math.max(0, n.nsn().length() - 4));
    }

Add it at the end of phone.go, the file from the Go guide:

// MayTextTo reports whether a one-time code may go to n: a mobile range in one of countries (ISO codes such as "GB").
func MayTextTo(n Number, countries []string) bool {
	return (n.Type == "mobile" || n.Type == "fixedLineOrMobile") && slices.Contains(countries, n.Region)
}

// RangeKey is one counter per block of 10,000 numbers: the country code and the national number without its
// last four digits.
func RangeKey(n Number) string { return "+" + n.CC + " " + n.NSN[:max(0, len(n.NSN)-4)] }

Add it inside the class in Phone.php, the file from the PHP guide:

    /** A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB). */
    public static function mayTextTo(array $number, array $countries): bool
    {
        return in_array($number['type'], ['mobile', 'fixedLineOrMobile'], true) && in_array($number['region'], $countries, true);
    }

    /** One counter per block of 10,000 numbers: the country code and the national number without its last four digits. */
    public static function rangeKey(array $number): string
    {
        return '+' . $number['cc'] . ' ' . substr($number['nsn'], 0, -4);
    }

Add it inside the module in phone.rb, the file from the Ruby guide:

  # A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB).
  def self.may_text_to?(number, countries)
    %w[mobile fixedLineOrMobile].include?(number.type) && countries.include?(number.region)
  end

  # One counter per block of 10,000 numbers: the country code and the national number without its last four digits.
  def self.range_key(number)
    "+#{number.cc} #{number.nsn[0...-4]}"
  end

Add it inside the class in Phone.cs, the file from the C# guide:

    /// <summary>A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB).</summary>
    public static bool MayTextTo(PhoneNumber n, IEnumerable<string> countries) =>
        (n.Type == "mobile" || n.Type == "fixedLineOrMobile") && countries.Contains(n.Region);

    /// <summary>One counter per block of 10,000 numbers: the country code and the national number without its last four digits.</summary>
    public static string RangeKey(PhoneNumber n) => $"+{n.Cc} {n.Nsn[..Math.Max(0, n.Nsn.Length - 4)]}";

Add it in src/phone.rs, before the tests, the file from the Rust guide:

/// A one-time code goes only to a mobile range in a country you serve (ISO codes such as GB).
pub fn may_text_to(n: &PhoneNumber, countries: &[&str]) -> bool {
    matches!(n.kind, "mobile" | "fixedLineOrMobile") && countries.contains(&n.region)
}

/// One counter per block of 10,000 numbers: the country code and the national number without its last four digits.
pub fn range_key(n: &PhoneNumber) -> String {
    format!("+{} {}", n.cc, &n.nsn[..n.nsn.len().saturating_sub(4)])
}