System keypad
T9 phone keypad
Legacy mobile phones mapped letters to digits 2–9. The system survives in vanity numbers and in mnemonic word ↔ number conversion.
Mapping
- 2
- A B C
- 3
- D E F
- 4
- G H I
- 5
- J K L
- 6
- M N O
- 7
- P Q R S
- 8
- T U V
- 9
- W X Y Z
Example
M·O·N·E·Y → 66639