T9 (predictive text)

[1] T9 was used on phones from Verizon, NEC, Nokia, Samsung Electronics, Siemens, Sony Mobile, Sanyo, SAGEM and others, as well as PDAs such as Avigo during the late 1990s.

Some phone manufacturers supply a permanent user database, while others do so for the duration of the session.

When the user enters matching keypresses, in addition to words and stems, the system also provides completions.

T9 can automatically recognize and correct typing/texting errors, by looking at neighboring keys on the keypad to determine an incorrect keypress.

Entering the same number but with two incorrect keypresses of neighboring keys, e.g. "8278494", results in T9 suggesting the words "tasting" (8278464), "testing" (8378464), and "tapping" (8277464).

This is a side effect of the requirements for small database sizes on the lower end embedded devices.

Many smart keyboards now exist, such as Swype or Swiftkey, that have taken the idea of T9 and combined it with the advanced touchscreen technology found in Android phones and iPhones.

Many features, such as predictive text, have been adopted by and improved by future generations of keyboard software.