Question: Is the NPI database up yet? I can't figure out where to look for it. Wyoming Subscriber Answer: Yes. At last you can look up the National Provider Identifier (NPI) of physicians who send patients to your office. The lookup is available online at http://nppes.cms.hhs.gov/NPPES/NPIRegistryHome.do. There has been some instability to the National Plan and Provider Enumeration System (NPPES) NPI Registry. CMS has been implementing changes that should eliminate the instability, according to Empire Medicare's Web site. During the changes, the NPI Registry was taken down and was unavailable to you. How it should work: The database includes real-time information. You can search the database by query using information such as a provider's name or NPI number. You-ll get a list of all NPPES records that meet the criteria you enter in the query. Once you select the record or records you wish to view, the NPI Registry displays the available information for that record. Watch out: In related news, CMS said it would start rejecting Part B claims when your NPI and legacy numbers don't match information in a crosswalk. Initially your carrier sent you "informational edits" when your information didn't match. But starting Sept. 3, Medicare began rejecting any non-matching claims.