N.C. Gen. Stat. § 62-270
It shall be the duty of every motor carrier operating under a certificate issued under the provisions of this Article to file with the Division of Motor Vehicles a designation in writing of the name and post-office address of a person upon whom service of notices or orders may be made under this Article. Such designation may from time to time be changed by like writing similarly filed. Service of notice or orders in proceedings under this Article may be made upon a motor carrier by personal service upon it or upon the person so designated by it, or by registered mail, return receipt requested, or by certified mail with return receipt requested, addressed to it or to such person at the address filed. In proceedings before the Commission involving the lawfulness of rates, charges, classifications, or practices, service of notice upon the person or agent who has filed a tariff or schedule in behalf of such carrier shall be deemed to be due and sufficient service upon the carrier.
N.C. Gen. Stat. § 62-270