The service supporting the RNL function is no longer in business.
We haven't been able to locate an alternative service that does not require each retailer to purchase a special license tied to successful hits by store's IP address. That scheme would be impractical to support.
Originally RNL worked 80-90% of the time based on landline searches. However, landline searches are of limited use nowadays since most consumers have mobile phones and cell phone companies do not support reverse number lookup. Search engines such as Google also don't support RNL due to privacy laws.
If and when we locate a suitable alternative, an update will be posted for download to re-enable RNL.