code: private static int parseCountryCode(String countryCode) {
  
      String normalized = countryCode;
      if (normalized.startsWith(InternationalCallPrefix.PREFIX_PLUS)) {
        normalized = normalized.substring(1);
      } else if (normalized.startsWith(InternationalCallPrefix.PREFIX_00)) {
        normalized = normalized.substring(2);
      } else if (normalized.startsWith(InternationalCallPrefix.PREFIX_011)) {
        normalized = normalized.substring(3);
      }
      if (normalized.startsWith("0")) {
        throw new IllegalArgumentException(countryCode);
      }
      try {
        int cc = Integer.parseInt(normalized);
        return cc;
      } catch (NumberFormatException e) {
        throw new IllegalArgumentException(countryCode, e);
      }
    }
docs: This method parses a {@link PhoneCountryCode} given as {@link String} to its {@link #getCountryCode() int
  representation}.
  
  @param countryCode is the {@link PhoneCountryCode} as {@link String}.
  @return the {@link PhoneCountryCode} as int.