CA Rev & Tax Code Section 41021

(a)

A service supplier shall collect the surcharge from each service user at the time it collects its billings from the service user, provided that the duty to collect the surcharge from a service user shall commence with the beginning of the first regular billing period applicable to that person which starts on or after the operative date of the surcharge imposed by this part. If the stations or lines of more than one service supplier are utilized in furnishing the telephone communication services to the service user, the service supplier that bills the customer shall collect the surcharge from the customer.

(b)

Only one payment under this part shall be required with respect to the surcharge on a service, notwithstanding that the lines or stations of one or more service suppliers are used in furnishing that service.