California
Code of Civil Procedure CCP § 1290.4
(a) A copy of the petition and a written notice of the time and place of the hearing thereof and any other papers upon which the petition is based shall be served in the manner provided in the arbitration agreement for the service of such petition and notice.
(b) If the arbitration agreement does not provide the manner in which such service shall be made and the person upon whom service is to be made has not previously appeared in the proceeding and has not previously been served in accordance with this subdivision:
(1) Service within this State shall be made in the manner provided by law for the service of summons in an action.
(2) Service outside this State shall be made by mailing the copy of the petition and notice and other papers by registered or certified mail. Personal service is the equivalent of such service by mail. Proof of service by mail shall be made by affidavit showing such mailing together with the return receipt of the United States Post Office bearing the signature of the person on whom service was made. Notwithstanding any other provision of this title, if service is made in the manner provided in this paragraph, the petition may not be heard until at least 30 days after the date of such service.
(c) If the arbitration agreement does not provide the manner in which such service shall be made and the person on whom service is to be made has previously appeared in the proceeding or has previously been served in accordance with subdivision (b) of this section, service shall be made in the manner provided in Chapter 5 (commencing with Section 1010 ) of Title 14 of Part 2 of this code.