If you’ve ever wondered about the best way to detect dial and DTMF tones from a phone line, [Debraj] is your man. [Debraj] built a DTMF detector using the Goertzel algorithm. Normally, when w… ...

But can someone tell me where the DTMF codes are in YouTube videos? I’ve used a DTMF decoder to get phone numbers from TV shows and movies and half the time they DON’T start with 555!!!