RuleFor(x => x.Phone)
                .Must(x => x == null || x?.CountryCode?.Code?.Length <= 16)
                .Must(x => x == null || Regex.IsMatch(x?.CountryCode?.Code, @"^+[1-9]{1,3}$|null"))
                .OverridePropertyName("PhoneCode")
                .WithMessage("String does not match pattern ^\+[1-9]{1,3}$");