Phone Keypad Decoder
Decode messages encoded with old phone keypad (T9/multi-tap). Common in geocaching puzzles.
Phone Keypad Reference
1
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
*
0
space
#
Encoding Formats
Multi-tap (T9)
Press count = letter position. "2" = A, "22" = B, "222" = C
HELLO → 44 33 555 555 666
Number Pairs
First digit = key, second = position. "21" = A, "22" = B, "23" = C
HELLO → 42 32 53 53 63
What is Phone Keypad Encoding?
Phone keypad encoding uses the letter layout of old mobile phones (before smartphones) to encode messages. Each number key (2-9) corresponds to 3-4 letters, and pressing the key multiple times cycles through those letters.
Phone Keypad Layout
| 1 | 2 ABC | 3 DEF |
| 4 GHI | 5 JKL | 6 MNO |
| 7 PQRS | 8 TUV | 9 WXYZ |
| * | 0 space | # |
Multi-tap Encoding
The most common format, based on how you would actually type on an old phone:
- 2 = A (press 2 once)
- 22 = B (press 2 twice)
- 222 = C (press 2 three times)
- 7777 = S (press 7 four times)
Example: "CACHE" = 222 22 222 44 33
Number Pair Encoding
An alternative format using two-digit codes:
- First digit = the key number
- Second digit = position (1, 2, 3, or 4)
Example: A = 21 (key 2, position 1), S = 74 (key 7, position 4)
Phone Keypad in Geocaching
Phone keypad puzzles are popular in geocaching because:
- Nostalgic: Many cachers remember old phone texting
- Easy to create: No special tools needed
- Reversible: Can encode or decode with same reference
- Visual cues: Often hidden in phone-related imagery
Recognizing Phone Keypad Ciphers
Look for these signs:
- Only digits 0-9: No letters or symbols
- Repeated digits: 22, 333, 7777 suggest multi-tap
- Two-digit groups: 21, 32, 74 suggest number pairs
- No 1s in multi-tap: Key 1 has no letters
- Spaces between groups: Separate letters
Special Keys
- 0: Usually represents a space
- 1: Typically unused (no letters) or represents punctuation
- * and #: Sometimes used for special characters
Variations
Different puzzles may use variations:
- Reversed: 2 = C, 22 = B, 222 = A
- Different separators: Commas, dashes, or no separators
- Mixed with other ciphers: Phone keypad then Caesar shift
Related Encoding Tools
- A1Z26: Simple letter-to-number where A=1, B=2, etc.
- ASCII Converter: Standard character encoding codes.
- Binary Converter: Text encoded in binary digits.