MP3 Audio Shield with DTMF Support | Sandbox Electronics
DTMF (Call Super Remix | Telephones
GitHub - bert2/DtmfDetection: C# implementation of the Goertzel algorithm for DTMF tone (a.k.a. Touch-Tone) detection and localization in audio data. Includes wrappers and extensions for NAudio.
How to make DTMF Phone Call Control Home Appliance Using Arduino and GSM Module | GSM DTMF Project - YouTube