# Blue Box

> DTMF and touch tone signal encoder/decoder with playback and customization. (iPhone/iPad app by Sunshine Valley Systems.)

- Source: https://appshunter.io/ios/app/blue-box/id391832739 (this page in markdown: same URL + `.md`)
- Developer: [Sunshine Valley Systems](https://appshunter.io/developer/327149814)
- Category: Utilities, Productivity
- Price: $4.99
- Rating: 5.00/5 from 3 App Store ratings · 18 written reviews indexed
- Age rating: 4+
- Requires: iOS 15.0 · 2 MB
- Languages: American English
- Released: 2010-09-20
- Data updated: 2026-08-14
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/blue-box/id391832739/reviews.md

## What is Blue Box?

Blue Box is utility for encoding and decoding DTMF (Dual-Tone Multi-Frequency) or Touch Tone signals.

Generate tones by using the phone style keypad or decipher tones using the device’s microphone.

Tone combinations can be played back with adjustable tone, delay and pause lengths and volume.

Choose from US, UK and Europe based systems.

Enable Multi-frequency tones, which were a precursor to DTMF. Additional trunk control signals will be available including KP, ST1, ST2, ST3, KP/ST2.

Additional tones include the Dial Tone, Ring Back Tone, Busy Signal and 2600Hz. A comma can be used as a pause character to provide extra time between tones during playback.

Save and organize any number of sequences for easy recall using the Favorites feature.

Choose numbers from your contacts to display and play back tones.

Share an encoded or decoded number with the Phone, FaceTime or Messages app.

Use Red Box mode to play coin tone sequences, including 5¢, 10¢ and 25¢ for the US system and 10p and 50p for European systems.

Create a custom tone with control over individual frequencies and volumes. The custom tone can consist of any number of on and off pulses and can optionally be continuous.

Record interactions with the encoder and play them back with the same timing. The recording feature works with all tones, including the dial tone, busy signal, ring back tone, 2600Hz and coins and trunk control tones.

A help manual is including, with step-by-step instructions for all features. When the app is first run, pop-ups will be displayed indicating what the controls are used for.

Warning:  Blue Box is designed as an educational tool and utility.  Do not attempt to use Blue for any illegal or malicious purposes.  Blue Box can be used to assist in dialing numbers, but can not be used to manipulate digital telephone utility services.

Limitations: Blue Box is software based decoding and is processor intensive.  Performance may vary between devices.  Tones that are less than 100 ms with pauses that are less than 100 ms are difficult to process in software.  Future versions and processors may increase the reliability of faster tone sequences.  If you need touch tone decoding for higher speeds, a hardware solution is recommended.

Blue Box can not play tones into the iPhone phone feature while in a call.

Blue Box is useful for entering numbers into touch tone operated systems such as an answering machine passcode or a dial-up service that requires the entering of several touch tones to navigate a menu system.  Simply enter the numbers once and then play back the numbers into the phone's microphone with a touch.

## Key features

- Encode/decode DTMF signals
- Adjustable tone, delay, and volume
- US, UK, and European tone systems
- Multi-frequency and trunk control tones
- Coin tone sequences (Red Box mode)
- Custom tone creation
- Save and organize sequences

## Recent user reviews (10 of 18)

All indexed reviews: https://appshunter.io/ios/app/blue-box/id391832739/reviews.md

### 5/5 — Works great

*2022-10-25*

First:  If you’re having trouble with this app… be sure to slide the switch on the side of your phone to in-mute it.  If your phone (or iPad) is muted, it can’t generate nor decode audio.

To the developer:  Great UI design.  I’m using this in my telephone systems class and it’s great.

Thanks for writing such a great app.

### 2/5 — I second “app name misleading”

*2020-01-19*

If only the author could get the correct tone matrix for the Blue Box.  

Wikipedia and other sources have the list of tones required. It should be easy to fix.

### 1/5 — Does not work for me

*2018-09-02*

Unfortunately this app does not work for me. After switching from dial to listen back to dial the output seems to be muted. Need to restart the app to regain output again. Listen mode only picks up noise, but no actual tones. Tried to adjust settings, but it got only worse. Installed a different app to decode tones which worked out of the box.

### 5/5 — All the tones you need

*2018-07-19*

Idk why this didn’t work at first. Without updating it now works. Sorry for the poor initial review!

### 5/5 — For those who know what this is

*2016-08-01*

I'm really happy and very surprised that this exists. Works very well. Only phone phreaks know what this is really used for, or what it used to be able to be used for.

### 5/5 — Perfect

*2016-06-08*

I've had this app for years now. Working in the telecom industry it has proven highly valuable.

### 1/5 — Not decode

*2016-02-11*

Decode not the true tone

### 5/5 — Real signal gen

*2014-12-15*

I have tested this with MC145436 DTMF decoder and LM358 used for condenser microphone preamp. If you are using an electronic hardware decoder this is the DTMF keypad you want. Most are playing back recorded samples, whereas this one is using low level audio framework to generate signal. The iPhone speaker begins to clap out at about half volume for DTMF. Works most reliably for me at about half volume for iPhone5.

### 2/5 — Listenback is not working

*2012-11-16*

Either it is incomparable with the iPhone 5, or iOS 6, but the decoding feature, which is the only reason I bought it (who needs to listen to dial tones?) is not working. I read all the trouble shooting methods, but it is obviously a version issue. Will be slightly less of a waste of money if they ever update it. Still don't know if its worth 3 bucks just for a decoder, but I needed one for work, and had to have it. What a let down.

### 5/5 — Really Nice App

*2012-04-15*

I came across this app while looking for a simple DTMF keyboard app to play DTMF tones and one ideally that had the ABCD tone combinations too. Several free apps were no good. This one came up in the search results for £1.99. No ratings or reviews as yet, but it's looks stood it apart from the free apps so I risked it.

It does everything I wanted plus more. 

Key features that I like.

1) In dial mode the tones last as long as you hold the button.
2) Includes A B C & D buttons.
3) CUSTOM allows you to set up your own tone pair.
4) The keyboard looks like a real pay-phone keypad rather than bland set of buttons that have had no thought put into them.
5) DTMF decoding function. I didn't even know it did this when I bought it. I already had 2 DTMF decoding APPS on my iPhone but this is much better. The others have been deleted now. It's great to have an all in one DTMF app.

This app is clearly written by people who have a passion for the subject.

## Frequently asked questions about Blue Box

### What is Blue Box used for?

Blue Box is a utility for encoding and decoding DTMF (Dual-Tone Multi-Frequency) or Touch Tone signals. It allows you to generate tones using a keypad or decipher them using your device's microphone, useful for interacting with systems like answering machines or dial-up services.

### Does Blue Box have ads?

No, Blue Box does not contain advertisements. It is a paid application that offers its full functionality without interruptions from ads.

### What tone systems does Blue Box support?

Blue Box supports US, UK, and European based DTMF systems. It also includes additional trunk control signals and special tones like Dial Tone, Ring Back Tone, Busy Signal, and 2600Hz.

### Can Blue Box play tones during a phone call?

No, Blue Box cannot play tones into the iPhone phone feature while in an active call. It is designed for use when not on a call or for other audio output scenarios.

### What are the limitations of Blue Box's decoding capabilities?

Blue Box's software-based decoding can be processor intensive, and performance may vary. Tones less than 100 ms with pauses less than 100 ms can be difficult to process. For higher speed decoding, a hardware solution is recommended.

### How does Blue Box handle saving tone sequences?

Blue Box features a Favorites feature that allows you to save and organize any number of tone sequences. This makes it easy to recall and play back frequently used combinations.

### What is the Red Box mode in Blue Box?

Red Box mode in Blue Box allows you to play coin tone sequences. This includes 5¢, 10¢, and 25¢ for the US system, and 10p and 50p for European systems, useful for simulating coin-operated interactions.

### Is Blue Box suitable for all devices?

Blue Box is supported on iPhone, iPad, and iPod. However, performance may vary between devices due to its processor-intensive software-based decoding.

## Version history (last 5 releases)

### 5.1.3 — 2023-09-21

The audio category was changed to ignore the mute switch.

### 5.1.2 — 2022-09-18

Fixed an issue that could cause a crash while trying to play empty recordings.

### 5.1 — 2022-08-16

New Feature: Added "Custom Tone Settings" option to favorites. When enabled, a volume, tone duration, delay and pause duration can be assigned to the favorite. When the favorite is used, the tone settings will be assigned to the playback settings. If not enabled, the current playback settings will be used.

Minor bug fixes and optimizations.

### 5.0 — 2022-07-17

Totally rewritten.
New user interface.
Improved decoding.
It is possible to adjust the volumes for the custom frequency, as well as add any number of on and off pulses. 
Send numbers to the Phone, FaceTime or Messages app.
New Recording feature makes it possible to record any interactions and play them back with the same timing. The recording feature works for all tones.
Added Attack/Decay setting to fade tones in and out.
Added informative pop-ups on first launch to explain the user interface.
Upgraded support feature to assist in provided feedback to customer support.
Searchable help feature.

### 4.1.1 — 2016-12-02

This app has been updated by Apple to display the Apple Watch app icon.

Added the privacy message for microphone use during DTMF decoding. This prevents a crash in iOS10 when the decoding button is pressed.
Minor bug fixes and optimizations.

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## More apps by Sunshine Valley Systems

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All apps by Sunshine Valley Systems: https://appshunter.io/developer/327149814

## Related topics

[dtmf](https://appshunter.io/ios/topics/dtmf) · [bluebox](https://appshunter.io/ios/topics/bluebox)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-14.*