Turns your iPhone into a simple DTMF decoder. Simply hold the iPhone's microphone near to a source of DTMF tones (telephone "Touch Tones") and it will display the numbers being dialed. Version 1.8+ not only has a far superior decoding engine, but it also allows you to tweak the sensitivity. You may copy the decoded digits to the clipboard from the text area.
Despite costing $0.99 in the iTunes store, this app remains Free Software.
Source code freely available under the GPL.
Update 2023-08-08: Version 1.11.1 is in the app store now.
Any queries, contact the author; make sure to include your email address.
Or go home.