Cal. Public Utilities Code § 829

(a) This article shall not apply to any person or corporation which transacts no business subject to regulation under this part, except performing services or delivering commodities for or to public utilities or municipal or other public corporations primarily for resale or use in serving the public or any portion thereof. This article shall apply to any public utility if the commission finds, in a proceeding to which the public utility is or may become a party, that the application of this article is required by the public interest. (b) (1) Except for Section 828, a telephone corporation that is not regulated under a rate-of-return regulatory structure is exempt from this article. This subdivision does not exempt a telephone corporation that is also an electrical corporation or a gas corporation, unless the commission determines the telephone corporation is exempt pursuant to subdivision (c). As used in this subdivision, a “rate-of-return regulatory structure” means a system under which the rates and charges of the telephone corporation are limited by a maximum permissible price that may be charged for a specific service. Telephone corporations regulated by a framework under which they may exercise pricing flexibility for all or most of the services offered are not regulated under a rate-of-return regulatory structure. (2) Notwithstanding paragraph (1), the commission may impose any requirement of this article on a telephone corporation if the commission finds, in a proceeding in which the telephone corporation is or may become a party, that the application of any provision of this article is required by the public interest. (c) The commission may from time to time by order or rule, and subject to such terms and conditions as may be prescribed therein, exempt any public utility or class of public utility from this article if it finds that the application thereof to such public utility or class of public utility is not necessary in the public interest.