This app is only available on the App Store for iOS devices.
Completely redesigned decoder!
Turns your iPhone into a simple DTMF decoder. Simply hold the iPhone's microphone near to a clear source of DTMF tones (telephone "Touch Tones") and it will display the numbers being dialed. The decoded digits are also placed into a text area from which you can copy them to the clipboard.
A row of LEDs indicate which frequencies are present in the signal - each LED corresponds to a single frequency.
See it in action here:
Source code freely available:
What's New in Version 1.8.2
Restored the ability to capture tones when the app is in the background.
Only usable on an iPhone 6S Plus at full sensitivity, and works poorly then.