Detect / Send DTMF Code

[NFC]

I want to design Auto Answering answering machine using microcontroller(measure some parameter ) and Connectivity control Serial from MIT App inventor. Cell phone communicate with Microcontroller using serial port.
In short cell phone act as Modem like SIM900.
How To Detect / Send DTMF Code when incoming Call is in progress.
I also want to know how to auto answer the incoming call.

[SteveJG]

The following information may help you.

@NFC

Connectivity control Serial from MIT App inventor.

See Connectivity

@NFC

and possibly these discussions BLE ESP32. Bluetooth. Send. Receive. Arduino IDE. Multitouch might be helpful which show various things you can use Serial to communicate with a microcontroller.

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How To Detect / Send DTMF Code when incoming Call is in progress.

What the community knows about DTMF

Regarding:

@NFC

how to auto answer the incoming call

How to use the Phone component with native Blocks