# Phone Home

### Challenge Overview

The challenge provides an audio file containing **DTMF tones**. The goal is to extract the hidden message from the audio and then decode it to obtain the final flag.

> **Note:** DTMF stands for **Dual-Tone Multi-Frequency**, a signaling system used in telecommunications to transmit keypad input (0-9, \*, #) over voice channels.

### DTMF Decoding

First, the audio file was analyzed using **multimon-ng** to decode the DTMF signals:

```bash
multimon-ng -t wav -a DTMF phonehome.wav
```

This command processes the WAV file and outputs a sequence of digits generated by the DTMF tones. The resulting output represents an **octal-encoded string**.&#x20;

> 15558675309#115145164141103124106173147060164137171060165162137156165155142063162065175

***

### Octal Decoding

The extracted octal string after "#" (the preceding digits likely representing the dialed phone number) was then decoded using **CyberChef**:

* Operation: **From Octal**
* Input: DTMF-decoded numeric output

After decoding, the operation reveals the plaintext message, which contains the **final flag**.

*made by k0d*
