SIM800 GSM Module and PCM


I need to get audio data from a GSM module into Arduino or ESP32 and then interface this data to Google Speech to text.

I noticed that the SIM800 modules have a PCM interface:


Would it be possible to use already existing libraries for I2S in order to get this data? Or do i need to code the serial communication all from scratch??

From what i gathered the PCM "interface" is very similar to I2S.


I have tested SIM800 for my project and it seems that do not support PCM output. When switching from analog audio to PCM audio by its AT commands, the analog audio is stopped but there is no any clock on PCM port.

The SIM800 doesn't support PCM but SIM800H and SIM800L do.
Be sure to check what model you have, many "SIM800" breakouts actually come with the SIM800L.

I'm also very interested about this as I'm trying to build an ESP32 based cellphone and I'd rather avoid the hassle of having to electronically switch the speaker between to sources (the ESP32 itself to ring the phone and the GSM module for the actual call).

If I can get it to work I'll post it here.

To moderators: Sorry to reopen this after four months but this is exactly what I was searching for, no point in opening another identical thread. Moreover, this is the first result on Google searching "Arduino SIM800 PCM", if someone else (like me) ends up here may find useful to know that some SIM800 module actually support PCM audio.