The hidden history of how we first texted each other

Music · Published 18 October 2026 Swipe more like this →

In short: Before smartphones and instant messaging, a technology designed to help the Deaf community communicate over analog phone lines laid the groundwork for modern texting. This journey from mechanical teleprinters to digital protocols reveals how accessibility needs often drive the most significant leaps in global communication.

The Telecommunications Device for the Deaf (TDD) originated as a way to transmit text over standard telephone lines using specialized hardware. In 1964, James C. Marsters and Robert Weitbrecht founded APCOM to develop the acoustic coupler—a device that allowed a standard Model 500 telephone to connect to old teleprinter machines. By converting keystrokes into unique sequences of tones via frequency-shift keying (FSK), they enabled half-duplex communication, where only one person could transmit at a time.

The technology evolved rapidly in the early 1970s. In 1973, Kit Patrick Corson and others premiered the Manual Communications Module (MCM), the world's first electronic portable TTY. While it was expensive at $599, its success led to a landmark tariff that allowed deaf persons to receive these devices for free. This era also saw the birth of relay services, allowing deaf individuals to communicate with hearing people via human operators who bridged the gap between text and voice.

The lineage of TDD is inextricably linked to the invention of modern text messaging. In 1994, Joseph Alan Poirier coined the term 'text messaging' while proposing a system for sending alerts to forklifts using multi-tap input—the same method used in Def-Tone Systems (DTS). While TDDs are now largely considered legacy devices as society moves toward Internet Protocol (IP) networks, they remain a vital lifeline for those without data access, proving that the architecture of our digital lives often begins with tools built for inclusion.

Today, while many use Real-Time Text over IP (RTT), the original TTY protocols still exist. These systems are technically distinct from computer ASCII codes, often relying on 5-bit Baudot codes. Despite being 'legacy,' these devices represent a triumph of engineering that forced major telecommunications companies to expand their networks for accessibility.

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