Cal. Pub. Util. Code § 741
(a) Every owner or operator of telephones available for public use, other than a telephone corporation, that accept any form of payment which, as part of the service furnished, provides operator-assisted services by other than a telephone corporation having tariff schedules on file with the commission providing for the furnishing of operator-assisted services, shall cause to be posted on or near the telephone equipment so as to be easily seen by telephone customers all of the following information:
(b) Every owner or operator of telephones available for public use, other than a telephone corporation, that accept any form of payment which, as part of the service furnished, provides operator-assisted services by other than a telephone corporation having tariff schedules on file with the commission providing for the furnishing of operator-assisted services, shall: