### Question
How is the "TDD" defined?


### Answer
The term **TDD** is defined in *47 U.S.C. § 225* as follows -

> a Telecommunications Device for the Deaf, which is a machine that employs graphic communication in the transmission of coded signals through a wire or radio communication system

#### Citation:
  - *47 U.S.C. § 225*
  - Heading: **CHAPTER 5-WIRE OR RADIO COMMUNICATION > SUBCHAPTER II-COMMON CARRIERS > Part I-Common Carrier Regulation**

