### Question
Can you define what pen register means?


### Answer
**Pen register** is defined as the following in *18 U.S.C. § 3127*:

> a device which records or decodes electronic or other impulses which identify the numbers dialed or otherwise transmitted on the telephone line to which such device is attached, but such term does not include any device 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 any device used by a provider or customer of a wire communication service for cost accounting or other like purposes in the ordinary course of its business

#### Citation:
  - *18 U.S.C. § 3127*
  - Heading: **PART II-CRIMINAL PROCEDURE > CHAPTER 206-PEN REGISTERS AND TRAP AND TRACE DEVICES**

