preferredInternationalPrefix property
If the international prefix that we want to use when formatting the number for out-of-country dialling contains non-digit symbols, or there is more than one international prefix is present, a preferred prefix can be specified here for out-of-country formatting purposes. If this field is not present, and multiple international prefixes are present, then "+" will be used instead.
Implementation
@$pb.TagNumber(17)
$core.String get preferredInternationalPrefix => $_getSZ(15);