Veh. Code, § 27908

(a) In every taxicab operated in this state there shall be a sign of heavy material, not smaller than 6 inches by 4 inches, or such other size as the agency regulating the operation of the taxicab provides for other notices or signs required to be in every taxicab, securely attached and clearly displayed in view of the passenger at all times, providing in letters as large as the size of the sign will reasonably allow, all of the following information:

(1) The name, address, and telephone number of the agency regulating the operation of the taxicab.

(2) The name, address, and telephone number of the firm licensed or controlled by the agency regulating the operation of the taxicab.

(b) In the event more than one local regulatory agency has jurisdiction over the operation of the taxicab, the notice required by paragraph (1) of subdivision (a) shall provide the name, address, and telephone number of the agency having jurisdiction in the area where the taxicab operator conducts its greatest volume of business; or, if this cannot readily be ascertained, the agency having jurisdiction in the area where the taxicab operator maintains its offices or primary place of business, provided that the operator conducts a substantial volume of business in such area; or, if neither of the foregoing provisions apply, any agency having jurisdiction of an area where the taxicab operator conducts a substantial volume of business.

(c) As used in this section, “taxicab” means a passenger vehicle designed for carrying not more than eight persons, excluding the driver, and used to carry passengers for hire. “Taxicab” shall not include a charter-party carrier of passengers within the meaning of the Passenger Charter-party Carriers’ Act, Chapter 8 (commencing with Section 5351) of Division 2 of the Public Utilities Code.