SainSmart SIM900 Breakout with microphone and speaker

Hello everyone,

I am not sure where else to go. I am using the GSM board mentioned in the title. In the description of it, it says, "The shield allows you to achieve SMS, MMS, GPRS and Audio via UART." This presumably means that connecting an electret microphone and a speaker is an option for this device.

However, there are only five pins coming out of the board: two grounds, power, rx and tx. The serial communication is for the AT commands, so there must be some other pins for the audio information.

On the SIM900 chip itself, there are two pins each for audio input and output. These are evidently the pins I need to communicate with, but the datasheets provided by SainSmart are for the chip itself, not the breakout board. The tutorial provided does not cover how to connect a speaker or a microphone.

TLDR: Using the SainSmart SIM900 breakout board, is it possible to send and receive audio information for making calls? If so, which pins are to be connected to the MCU? If not, can anyone recommend a breakout board for the SIM900 with just power, ground, rx, tx, mic, and speaker pins?

Component: [Discontinued] SIM900 GPRS/GSM Board Quad-Band Module Kit for Arduino – SainSmart.com

After a quick search, I can find no answers to your questions. But,

I see this not in the factory documentation:

"NB! SIM900 is EOL now. Limited quantity available. Please consider to use SIM800x series modules.".

So, the unit is using devices that are really cheap because they are not longer being produced.

Paul