code: private static String toInternational(PhoneNumber phoneNumber) throws PhoneNumberException {
  		String number = phoneNumber.getNumber();
  		if (number.startsWith("+") || number.length() == INTERNATIONAL_FORMAT_LENGTH) {
  			return StringUtils.leftPad(number.replace("+", "").replaceAll("\\s+", ""), INTERNATIONAL_FORMAT_LENGTH, '0');
  		} else {
  			throw new IllegalArgumentException("Invalid phone number. OVH only accepts international phone numbers. Please write the phone number with the country prefix. "
  					+ "For example, if the number is 0601020304 and it is a French number, then the international number is +33601020304");
  		}
  	}
docs: Convert a raw phone number to its international form usable by OVH (13
  digits with no space).
  
  @param phoneNumber
  the phone number to transform
  @return the international phone number
  @throws PhoneNumberException