Which device is outdated for exchanging written messages by telephone?

• A. Fax Machine
• B. Teletypewriter (TTY or TDD)
• C. Email
• D. Smartphone

Answer: (B)

The key idea is how written messages were transmitted over telephone networks. Teletypewriter (TTY or TDD) was specifically built to send typed text across phone lines, letting a Deaf or hard-of-hearing person communicate by typing at one end and reading text at the other. In practice, you needed compatible hardware at both ends, and it relied on older phone signaling and dedicated devices.

Today, written communication over phones is dominated by text messaging on smartphones and real-time captions or video calls. These methods don’t require a separate teletype device or the old TTY protocols, making TTY largely obsolete for this purpose. While fax machines still exist for document transmission over phone lines, they’re not the primary way to exchange written messages in the way TTY was designed for. Email operates over the internet, not the telephone network, so it doesn’t fit the telephone-based messaging idea.