T9 (predictive text)

T9 is a predictive text technology for mobile phones (specifically those that contain a 3×4 numeric keypad), originally developed by Tegic Communications, now part of Nuance Communications. T9 stands for Text on 9 keys. 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. The main competing technologies include iTap created by Motorola, SureType created by RIM, Eatoni's LetterWise and WordWise, and Intelab's Tauto. T9 is not available on Apple devices but is available on certain inexpensive phones without a touchscreen, and modern Android phones where it can be used to dial contacts by spelling the name of the contact one is trying to call. The technology was protected by multiple US patents, but they have since expired. T9's objective is to make it easier to enter text messages. It allows words to be formed by a single keypress for each letter, which is an enormous improvement over the multi-tap approach used in conventional mobile phone text entry at the time, in which several letters are associated with each key, and selecting one letter often requires multiple keypresses. T9 combines the groups of letters on each phone key with a fast-access dictionary of words. It will then look up in the dictionary all words corresponding to the sequence of keypresses and order them by frequency of use. As T9 "gains familiarity" with the words and phrases the user commonly uses, it speeds up the process by offering the most frequently used words first and then letting the user access other choices with one or more presses of a predefined "Next" key. The dictionary is expandable. After introducing a new word, the next time the user tries to produce that word, T9 adds it to the predictive dictionary. The user database (UDB) can be expanded via multi-tap. The implementation of the user database is dependent on the version of T9 and how T9 is actually integrated on the device.