A pen register is a:

A.
Device that records the caller-ID of incoming calls

B.
Device that records the URLs accessed by an individual

C.
Device that identifies the cell in which a mobile phone is operating

D.
Device that records all the numbers dialed from a specific telephone line

Explanation:
(Electronic Privacy Information Center, Approvals for Federal Pen Registers and Trap and Trace
Devices 1987-1998, www.epic. org). Gathering information as to which numbers are dialed from a
specific telephone line is less costly and time-consuming than installing a wiretap and recording the
information. * There is also equipment that can record the information listed in answers “Device
that identifies the cell in which a mobile phone is operating” and “Device that records the URLs
accessed by an individual”. * The device referred to in answer “Device that records the caller-ID of

incoming calls” is called a trap-and-trace device. All of the answers in this question are a subset of
the category of traffic analysis wherein patterns and frequency associated with communications are
studied instead of the content of the communications.