Cal. Health and Safety Code § 121920

(a) The owner or trainer of any attack, guard, or sentry dog shall ensure that the dog has been microchipped and the owner’s identification has been entered into a local or national registry. Each dog subject to this chapter shall, at all times, wear an identification tag. The identification tag shall be provided by the attack, guard, or sentry dog company furnishing the dog for hire. The identification tag shall contain, but not be limited to, the following information: The name of the dog. The name, address, and telephone number of the attack, guard, or sentry dog company furnishing the dog for hire. Any telephone number so provided shall be to a telephone that is manned by a person 24 hours per day every day of the year so that calls from the public may be received and answered. (b) The identification tag required by this section shall be in addition to any tag required or issued by any agency of government to show that a dog has been immunized or inoculated against disease.