You probably remember T9, even if you don’t remember it being called that. Remember the first text messages you sent? You probably had a phone like this one:

and you sent that message laboriously, one letter at a time. Press the number “2” once for “a”, twice for “b,” etc. Is it all coming back to you now?

T9’s original mission

T9 was a technique for predicting words based on the nine-button keypad of a phone. It was actually developed as an assistive technology, for people who could not type or who had mobility problems. Martin King, Dale Grover, and Cliff Kushler developed the text-prediction algorithms to help people form words by moving their eyes in one direction or another. It’s all laid out in this article. Although T9 was first developed for eye tracking, it was soon to make a move over to cell phones.

If you’re like most folks you probably sent your first text sometime in the mid-2000s. The United States was actually pretty late to get on the texting bandwagon. In Europe and Asia, where unlimited plans were rare, texting was much more common. Believe it or not, SMS text messaging, which is still the standard used today, was first developed in 1992 and the first texting plan for mobile devices was rolled out in 1994.

Why T9 was so important

Today, we take for granted the idea that we can text quickly using an onscreen keyboard or even voice dictation. With early cell phones however texting was a much harder process. It was possible to begin to become proficient but it took most people a long time just to type out short messages.

Texting slang rose up immediately. Some is still with us, such as “u” for “you” and “lol” for “laughing out loud” (although you can be sure that if someone texts you “lol” they are very rarely laughing.) It was also common to shorten words and drop vowels. Every letter was valuable in texting, not just because the messages needed to be short. You also had to save time creating them.

T9 solved a lot of problems by predicting words as you typed. This was revolutionary. Simply pressing a few buttons gave you a predictive result. Depending on the logic used in your phone, the result could be based on what you had typed in the past, or just on words likely to follow what you typed. Either way, it made texting not only possible but fun.

The legacy of T9

T9 lost its luster when smartphones came into being. It became less important to predict the next word when you could type quickly. At the same time, smartphones had more memory, faster processors, and therefore could actively fix spelling errors. Your texted slang could automatically change into properly spelled words if you wished.

Still, T9’s core mission didn’t go away. Today’s phones still have predictive text engines that are based on T9’s original work. They’ve become a lot smarter and more aware of sentence structure. In fact predictive text is so smart that it can actually write complete sentences. If you don’t believe me, start a text and then just choose the predictive answer. I just did that on my phone and I got “I’m glad you are having fun with us tomorrow at the store.” That’s better English than most of my friends.

By the way, if you still want to use T9, you can use the same system in the search box of DIRECTV receivers. Press the number “2” once for “a,” twice for “b”… don’t worry it will all come back to you.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 8,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.