-specificed destination. Destination can be specified as an FS::rate_detail
-object or regionnum (see L<FS::rate_detail>), or as a hashref with two keys:
-I<countrycode> and I<phonenum>.
+specificed destination, or the empty string if no rate can be found for
+the given destination.
+
+Destination can be specified as an FS::rate_detail object or regionnum
+(see L<FS::rate_detail>), or as a hashref with two keys: I<countrycode>
+and I<phonenum>.