Which communication method is not a recent digital technology for deaf and hearing-impaired individuals?

TTY (Teletypewriter) and TDD (Telecommunication Device for the Deaf) are traditional technologies designed for deaf and hard-of-hearing individuals. These devices have been in use since the 1960s and allowed users to send typed messages over telephone lines. While technology has evolved significantly since then, TTY/TDD has remained a staple for telephone communication in the deaf community, predating the digital communication methods that emerged in the late 20th and early 21st centuries, such as instant messaging (IM), Skype, and live chat, which are all rooted in more recent advancements in internet-based communications.

In contrast, Skype, live chat, and instant messaging represent technologies that have become widely accessible only in the era of broadband internet and digital communication, enabling real-time communication through text, video, or both, specifically tailored to the needs of deaf and hearing-impaired individuals in a more versatile and interactive manner. Thus, TTY/TDD stands out as a foundational technology that is not considered recent compared to these digital innovations.