public static boolean validateInternationalPhoneNumberFormat(String phone) {
StringBuilder sb = new StringBuilder(200);
// Country code
sb.append("^(\\+{1}[\\d]{1,3})?");
// Area code, with or without parentheses
sb.append("([\\s])?(([\\(]{1}[\\d]{2,3}[\\)]{1}[\\s]?)|([\\d]{2,3}[\\s]?))?");
// Phone number separator can be "-", "." or " "
// Minimum of 5 digits (for fixed line phones in Solomon Islands)
sb.append("\\d[\\-\\.\\s]?\\d[\\-\\.\\s]?\\d[\\-\\.\\s]?\\d[\\-\\.\\s]?\\d[\\-\\.\\s]?");
// 4 more optional digits
sb.append("\\d?[\\-\\.\\s]?\\d?[\\-\\.\\s]?\\d?[\\-\\.\\s]?\\d?$");
return Pattern.compile(sb.toString()).matcher(phone).find();
}