Cal. Penal Code § 635

(a) Every person who manufactures, assembles, sells, offers for sale, advertises for sale, possesses, transports, imports, or furnishes to another any device which is primarily or exclusively designed or intended for eavesdropping upon the communication of another, or any device which is primarily or exclusively designed or intended for the unauthorized interception or reception of communications between cellular radio telephones or between a cellular radio telephone and a landline telephone in violation of Section 632.5, or communications between cordless telephones or between a cordless telephone and a landline telephone in violation of Section 632.6, shall be punished by a fine not exceeding two thousand five hundred dollars ($2,500), by imprisonment in the county jail not exceeding one year, or in the state prison, or by both that fine and imprisonment. If the person has previously been convicted of a violation of this section, the person shall be punished by a fine not exceeding ten thousand dollars ($10,000), by imprisonment in the county jail not exceeding one year, or in the state prison, or by both that fine and imprisonment. (b) This section does not apply to either of the following: (1) An act otherwise prohibited by this section when performed by any of the following: (A) A communication utility or an officer, employee or agent thereof for the purpose of construction, maintenance, conduct, or operation of, or otherwise incident to the use of, the services or facilities of the utility. (B) A state, county, or municipal law enforcement agency or an agency of the federal government. (C) A person engaged in selling devices specified in subdivision (a) for use by, or resale to, agencies of a foreign government under terms approved by the federal government, communication utilities, state, county, or municipal law enforcement agencies, or agencies of the federal government. (2) Possession by a subscriber to communication utility service of a device specified in subdivision (a) furnished by the utility pursuant to its tariffs.