iText and iTap are two predictive text input systems for writing messages in cell phones like Nokia and Motorola.
iText allows you to enter text by pressing once on a key for each letter of a word, and it will predict whole words as you key press. For example, to type the word “tomorrow”, press 8 6 6 6, “tomorrow” will be predicted as candidate.
iTap allows you to multi-tap each letter, but will predict and display complete words that contain your sequence of key presses. If your target word is not proposed, simply continue to multi-tap the complete word. For example, to type the word “welcome”, press 9 for letter “w”, press 33 for “e” and press 555 for “l”, “welcome” will be predicted as candidate.
Spell? - This personal dictionary function allows you to multi-tap your own words that not included in the static database, and saved for future prediction.
You can save all words not included in the static database for future prediction, and learn and promote frequently used words. Predict the next word by using learned phrases to propose the next word without pressing another key. You can capitalize the next character after a full stop punctuation followed by a space. And you now are able to insert Smiley like happy :).

And the various key pad numbers in your mobile phones will surely functions different:
‘0’ - Inserts space
‘+-‘- Next candidate (Single candidate display mode)/ Symbol table
Joystick Up/Down – Candidate navigation (Multiple candidate display mode)
Joystick Left – Accept the typed portion of the candidate
Joystick Right – Accept candidate without space
‘#’ short press – Capitalization mode switch
‘#’ long press – Input mode switch
‘1’ short press – Smart punctuation
Pencil Button – Edit / Copy / Paste