Formerly known as provider identification number (PIN). It is a carrier-assigned number that every facility, physician, clinic, or organization uses that renders services to patients when submitting insurance claims. It is issued to a provider by the insurance carrier or Medicare fiscal intermediary and allows the physician or patient to receive reimbursement for claims filed to the contractor. Also referred to as a legacy number. PINs have been replaced with the national provider identifiers (NPIs). See national provider identifier (NPI).