Cal. PEN § 637.1

Every person not connected with any telegraph or telephone office who, without the authority or consent of the person to whom the same may be directed, willfully opens any sealed envelope enclosing a telegraphic or telephonic message, addressed to another person, with the purpose of learning the contents of such message, or who fraudulently represents another person and thereby procures to be delivered to himself any telegraphic or telephonic message addressed to such other person, with the intent to use, destroy, or detain the same from the person entitled to receive such message, is punishable as provided in Section 637.