## DTMF Frequencies Decoder

## DTMF Frequencies Encoder

## Answers to Questions

### What are DTMF Codes? (Definition)

A **DTMF** code for dual-tone multi-frequency, is the name given to a combination of sound frequencies (beep) emitted by the keys of a telephone keypad. They are used by voice servers and for dialing numbers.

### How to encrypt a number using DTMF Codes?

**DTMF** codes are used by phones and can be used to substitute numbers with their sound wave frequency as described in the table:

1209 Hz | 1336 Hz | 1477 Hz | 1633 Hz | |

697 Hz | 1 | 2 | 3 | A |

770 Hz | 4 | 5 | 6 | B |

852 Hz | 7 | 8 | 9 | C |

941 Hz | * | 0 | # | D |

Example: To crypt DC0D3, look for D which is the combination of 941Hz and 1633Hz, then write it 1633-941 (or 941-1633). The complete ciphered message is 1633-941/1633-852/1336-941/1633-941/1477-697

### How to decrypt Codes DTMF cipher?

Decryption is a simple reverse substitution, for each frequency, a digit or a letter is associated.

### How to recognize DTMF Codes?

There are only 8 frequencies: 697 Hz, 770 Hz, 852 Hz, 941 Hz, 1209 Hz, 1336 Hz, 1477 Hz and 1633 Hz.

### What does DTMF means?

**DTMF** stands for dual-tone multi-frequency and translates sometimes into Vocal Frequencies.

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