Title 18 of the United States Code defines a trap and trace device as follows: A trap and trace device shows what numbers had called a specific telephone—i.e., all incoming phone numbers.
They are often jointly referred to as "Pen Register or Trap and Trace devices" to reflect the fact that the same program will probably do both functions in the modern era, and the distinction is not that important.
[citation needed] Uses of trap and trace devices are a sunset provision of the USA PATRIOT Act.
Prior to the enactment of the USA PATRIOT Act, the Foreign Intelligence Surveillance Act was exempt from laws regarding the acquisition of "dialing, routing, addressing, or signaling information, ... provided, however, that such information shall not include the contents of any communication.
"[1] Along with giving the government easier access to communications between the sender and receiver, section 214 of PATRIOT ACT eliminated the prerequisite that the government prove that the suspect is, "an agent of foreign power".