California Penal Code Section 631
(a) Any person who, by means of any machine, instrument, or
contrivance, or in any other manner, intentionally taps, or makes any
unauthorized connection, whether physically, electrically,
acoustically, inductively, or otherwise, with any telegraph or
telephone wire, line, cable, or instrument, including the wire, line,
cable, or instrument of any internal telephonic communication
system, or who willfully and without the consent of all parties to
the communication, or in any unauthorized manner, reads, or attempts
to read, or to learn the contents or meaning of any message, report,
or communication while the same is in transit or passing over any
wire, line, or cable, or is being sent from, or received at any place
within this state; or who uses, or attempts to use, in any manner,
or for any purpose, or to communicate in any way, any information so
obtained, or who aids, agrees with, employs, or conspires with any
person or persons to unlawfully do, or permit, or cause to be done
any of the acts or things mentioned above in this section, is
punishable by a fine not exceeding two thousand five hundred dollars
($2,500), or by imprisonment in the county jail not exceeding one
year, or by imprisonment in the state prison, or by both a fine and
imprisonment in the county jail or in the state prison. If the person
has previously been convicted of a violation of this section or
Section 632, 632.5, 632.6, 632.7, or 636, he or she is punishable by
a fine not exceeding ten thousand dollars ($10,000), or by
imprisonment in the county jail not exceeding one year, or by
imprisonment in the state prison, or by both a fine and imprisonment
in the county jail or in the state prison.
(b) This section shall not apply (1) to any public utility engaged
in the business of providing communications services and facilities,
or to the officers, employees or agents thereof, where the acts
otherwise prohibited herein are for the purpose of construction,
maintenance, conduct or operation of the services and facilities of
the public utility, or (2) to the use of any instrument, equipment,
facility, or service furnished and used pursuant to the tariffs of a
public utility, or (3) to any telephonic communication system used
for communication exclusively within a state, county, city and
county, or city correctional facility.
(c) Except as proof in an action or prosecution for violation of
this section, no evidence obtained in violation of this section shall
be admissible in any judicial, administrative, legislative, or other
proceeding.
(d) This section shall become operative on January 1, 1994.