The address of record and telephone number required under this part shall be considered the operator's official address and telephone number for purposes of the Act. Service of documents upon the operator may be proved by a post office return receipt showing that the documents could not be delivered to such operator at the address of record because the operator had moved without leaving a forwarding address or because delivery was not accepted at that address, or because no such address existed. However, operators may request service by delivery to another appropriate address provided by the operator. The telephone number required under this part will be used in connection with proposed civil penalty assessments as provided in 30 CFR part 100.