Cal. Penal Code § 633.1

(a) Nothing in Section 631, 632, 632.5, 632.6, or 632.7 prohibits any person regularly employed as an airport law enforcement officer, as described in subdivision (d) of Section 830.33, acting within the scope of his or her authority, from recording any communication which is received on an incoming telephone line, for which the person initiating the call utilized a telephone number known to the public to be a means of contacting airport law enforcement officers. In order for a telephone call to be recorded under this subdivision, a series of electronic tones shall be used, placing the caller on notice that his or her telephone call is being recorded. (b) Nothing in Section 631, 632, 632.5, 632.6, or 632.7 renders inadmissible any evidence obtained by an officer described in subdivision (a) if the evidence was received by means of recording any communication which is received on an incoming public telephone line, for which the person initiating the call utilized a telephone number known to the public to be a means of contacting airport law enforcement officers. (c) This section shall only apply to airport law enforcement officers who are employed at an airport which maintains regularly scheduled international airport service and which maintains permanent facilities of the United States Customs Service.