(a) When required. In every administrative proceeding, each paper, including each notice of appearance, written motion, brief, or other written communication, shall be served upon each party in the proceeding in accordance with the provisions of this section; provided, however, that absent an order to the contrary, no service shall be required for motions which may be heard ex parte.

(b) Upon a person represented by counsel. Whenever service is required to be made upon a person represented by counsel who has filed a notice of appearance pursuant to §201, service shall be made pursuant to paragraph (c) of this section upon counsel, unless service upon the person represented is ordered by the hearing officer.

(c) How made. Service shall be made by delivering a copy of the filing. Delivery means:

(1) Personal service by handing a copy to the person required to be served; or leaving a copy at the person’s office with a clerk or other person in charge thereof, or, if there is no one in charge, leaving it in a conspicuous place therein; or, if the office is closed, or the person to be served has no office, leaving it at the person’s dwelling house or usual place of abode with some person of suitable age and discretion then residing therein;

(2) Mailing the papers through the U.S. Postal Service by first class, registered, or certified mail or Express Mail delivery addressed to the person;

(3) Sending the papers through a commercial courier service or express delivery service; or

(4) Transmitting the papers by facsimile machine where the following conditions are met:

(i) The persons serving each other by facsimile transmission have agreed to do so in a writing, signed by each party, which specifies such terms as they deem necessary with respect to facsimile machine telephone numbers to be used, hours of facsimile machine operation, the provision of non-facsimile original or copy, and any other such matters; and

(ii) Receipt of each document served by facsimile is confirmed by a manually signed receipt delivered by facsimile machine or other means agreed to by the parties.

(d) When service is complete. Personal service, service by U.S. Postal Express Mail or service by commercial courier or express delivery service is complete upon delivery. Service by mail is complete upon mailing. Service by facsimile is complete upon confirmation of transmission by delivery of a manually signed receipt.