Cal. Rev. & Tax. Code § 42102
(a) Notwithstanding any other law, on and after January 1, 2016, the authority of a city, county, or city and county, which includes a charter city, county, or city and county, to impose a utility user tax on the consumption of prepaid mobile telephony service in the city, county, or city and county at the rate as specified in an ordinance authorized pursuant to Section 7284.2 or any other law is suspended, and the utility user tax rate to be applied instead during the period under any ordinance as so adopted is the applicable of the following:
(d) On and after January 1, 2016, this part shall be all of the following:
(1) The exclusive method for both of the following: