T9 Predictive Text
Convert between text and T9 number sequences. Find dictionary words from T9 input.
Enter number sequences (use 0 or space for word breaks)
T9 Keypad
T9 vs Multi-tap
| Feature | T9 | Multi-tap |
|---|---|---|
| "hello" | 43556 | 44 33 555 555 666 |
| Ambiguity | Multiple words possible | Unambiguous |
| Input speed | Faster (1 press/letter) | Slower (1-4 presses) |
Puzzle Tips
- • Multiple words can map to the same numbers (textonyms)
- • 4663 = "good", "home", "gone", "hoof"
- • Context clues help determine the right word
- • If T9 doesn't produce words, try multi-tap decoding
What is T9 Predictive Text?
T9 (Text on 9 keys) was a predictive text technology for mobile phones with numeric keypads. Unlike multi-tap where you press a key multiple times, T9 uses a dictionary to predict words from single key presses.
How T9 Works
The Concept
- Press each key once per letter (2=ABC, 3=DEF, etc.)
- The system matches the number sequence against a dictionary
- If multiple words match, cycle through them
Example
To type "hello": Press 4-3-5-5-6. The system checks which dictionary words match this sequence and offers "hello" as an option.
Textonyms
Textonyms are different words that share the same T9 sequence:
- 4663 = good, home, gone, hood, hoof
- 7233 = pace, race, sade
- 2665 = book, cool, cook, bool
T9 Key Mapping
- 2 = ABC
- 3 = DEF
- 4 = GHI
- 5 = JKL
- 6 = MNO
- 7 = PQRS
- 8 = TUV
- 9 = WXYZ
- 0 = Space
In Geocaching
T9 appears in puzzles because:
- Nostalgia: Many cachers remember T9 from early phones
- Ambiguity: Textonyms add puzzle complexity
- Phone themes: Puzzles involving old technology
- Number sequences: Coordinates hidden as T9
Related Encodings
- Multi-tap: Press key multiple times for specific letter.
- A1Z26: Simple letter-to-number encoding.
- Phone Keypad: General phone number encodings.