California Code, Revenue and Taxation Code - RTC § 42101.9

(a) Except as provided in subdivisions (b) and (c), if prepaid mobile telephony services are sold in combination with mobile data services or any other services or products that are not subject to the local charges for a single price, then the local charges shall apply to the entire price unless the seller can identify the mobile data services and other services or products from its books and records kept in the ordinary course of business.

(b) If prepaid mobile telephony services are sold with a mobile telephone service communication device, commonly termed a cellular telephone, for a single, nonitemized price, then the local charges shall apply to the entire nonitemized price, except if the purchase price for the cellular telephone component of the bundled charge is disclosed to the prepaid consumer on a receipt, invoice, or other written or electronic documentation provided to the prepaid consumer, the local charges may be calculated excluding the separately stated price of the cellular telephone.

(c) If a minimal amount of prepaid mobile telephony service is sold for a single, nonitemized price with a mobile telephony service communications device, the seller shall not apply the local charges to the transaction.  For these purposes, a service allotment denominated as 10 minutes or less, or five dollars ($5) or less, is a minimal amount.