California Code, Corporations Code - CORP § 15800

(a) Every partnership, other than a foreign limited partnership, subject to Chapter 4.5 (commencing with Section 15900), or a commercial or banking partnership established and transacting business in a place outside the United States, that is domiciled without this state and has no regular place of business within this state, shall, within 40 days from the time it commences to do business in this state, file a statement in the office of the Secretary of State in accordance with Section 16309 designating some natural person or corporation as the agent of the partnership upon whom process issued by authority of or under any law of this state directed against the partnership may be served.  A copy of the designation, duly certified by the Secretary of State, is sufficient evidence of the appointment.

(b) The process may be served in the manner provided in subdivision (b) of Section 16310 on the person so designated, or, in the event that no person has been designated, or if the agent designated for the service of process is a natural person and cannot be found with due diligence at the address stated in the designation, or if the agent is a corporation and no person can be found with due diligence to whom the delivery authorized by subdivision (b) of Section 16310 may be made for the purpose of delivery to the corporate agent, or if the agent designated is no longer authorized to act, then service may be made by personal delivery to the Secretary of State, Assistant Secretary of State, or a Deputy Secretary of State of the process, together with a written statement signed by the party to the action seeking the service, or by the party's attorney, setting forth the last known address of the partnership and a service fee as set forth in Section 12197 of the Government Code.  The Secretary of State shall immediately give notice of the service to the partnership by forwarding the process to it by registered mail, return receipt requested, at the address given in the written statement.

(c) Service on the person designated, or personal delivery of the process and statement of address together with a service fee as set forth in Section 12197 of the Government Code to the Secretary of State, Assistant Secretary of State, or a Deputy Secretary of State, pursuant to this section is a valid service on the partnership.  The partnership so served shall appear within 30 days after service on the person designated or within 30 days after delivery of the process to the Secretary of State, Assistant Secretary of State, or a Deputy Secretary of State.