California Penal Code
For purposes of this chapter, the following terms have the following meanings:
(a) “Wire communication” and “electronic communication” have the meanings set forth in subdivision (a) of Section 629.51.
(b) “Pen register” means a device or process that records or decodes dialing, routing, addressing, or signaling information transmitted by an instrument or facility from which a wire or electronic communication is transmitted, but not the contents of a communication. “Pen register” does not include a device or process used by a provider or customer of a wire or electronic communication service for billing, or recording as an
incident to billing, for communications services provided by such provider, or a device or process used by a provider or customer of a wire communication service for cost accounting or other similar purposes in the ordinary course of its business.
(c) “Trap and trace device” means a device or process that captures the incoming electronic or other impulses that identify the originating number or other dialing, routing, addressing, or signaling information reasonably likely to identify the source of a wire or electronic communication, but not the contents of a communication.