My FFL gave me the numbers, shouldn't be a problem with any dealer, they don't need to provide the entire number. The site will provide the licensee's name, license expiration date, their trade name, premise address and mailing address, as well as the following warning:
NOTE: In the event all of the information on the license you are verifying does not match the information displayed above, or if the license has expired, there is a possibility that this may be an attempt at a fraudulent transaction. You should not complete the transaction without first contacting ATF at 1-877-560-2435 for assistance.
The data obtained from this site is not a substitute for a certified copy of the license.
Tim