Cal. Gov't Code § 53110

(a) Every system shall include police, firefighting, and emergency medical and ambulance services, and may include other emergency services, in the discretion of the affected local public agency, such as poison control services, suicide prevention services, and civil defense services. The system may incorporate private ambulance service. In areas in which a public safety agency of the state provides emergency services, the system shall include the public safety agency or agencies.
(b) Notwithstanding subdivision (a), a public agency shall not delegate, assign, or enter into a contract for “911” call processing services for the dispatch of emergency response resources except as provided in subdivision (c) or if the delegation or assignment is to, or the contract or agreement is with, another public agency.
(c) Notwithstanding subdivision (b), the following entities may delegate or assign to a nonpublic agency, or contract with a nonpublic agency for, “911” call processing services only as described in paragraphs (1) and (2).
1. (1) A joint powers authority that delegated, assigned, or contracted for “911” call processing services on or before January 1, 2019, may continue to delegate, assign, or contract for those services and may, upon the expiration of the delegation, assignment, or contract, renegotiate or adopt new contracts, if the membership of the joint powers authority includes all public safety agencies that provide prehospital emergency medical services and the joint powers authority consents to the continued delegation, assignment, or renegotiation or adoption of the contract.
2. (2) A public agency that has delegated, assigned, or contracted for “911” call processing services on or before January 1, 2019, may continue to do so with the concurrence of the public safety agencies that provide prehospital emergency medical services. If a public safety agency does not concur with the delegation, assignment, or contracting of the “911” call processing services within its jurisdictional boundaries, the following shall apply:
  1. (A) The public agency may continue to delegate, assign, or contract for “911” call processing services as described in this paragraph for the remaining concurring public safety agencies, and the nonconcurring public safety agency shall discharge “911” call processing duties within its jurisdictional boundaries. Notwithstanding this subparagraph, if the delegation, assignment, or contract provided the option for one or more public safety agencies to withdraw from the delegation, assignment, or contract, the terms of that delegation, assignment, or contract shall prevail.
  2. (B) If continuing the delegation, assignment, or contract described in subparagraph (A) is not feasible, the withdrawing public safety agency shall assume “911” call processing services for the service area originally subject to delegation, assignment, or contract.
(d) This section does not prohibit a public agency or public safety agency from entering into an agreement for backup “911” call processing services.