DNIS (Dialed Number Identification Service) is a telephone service that identifies for the receiver of a call the number that the caller dialed. It's a common feature of 800 and 900 lines. If you have multiple 800 or 900 numbers to the same destination, DNIS tells which number was called.
ANI (Automatic number identification) is a feature of telephony intelligent network services which permits subscribers to display or capture the telephone numbers of calling parties.
If an H.323 gateway is used, incoming calls can be blocked based on either Automatic Number Identifier (ANI) or Dialed Number Identification Service (DNIS) information, or both, through translation rules on the gateway (GW) configuration.
If blockage of a specific number (ANI) is desired, a translation-profile must be created with a translation-rule matching that number. Then, apply the command to block.