ANI Normalization when enabled, will determine if a 10 digit ANI provided in the incoming SIP Invite (taken from the PAI, RPID, or From Header in that order) is a valid US number by checking the LERG. If the ANI is valid then it will prepend the number with 1 as the country code and continue to process the SIP Invite. If the ANI is not in the LERG the number will be treated as an International number.
This feature applies to Termination Customer and Origination Vendor Trunk Groups