Hi Everybody ,
I try the A6 module , works fine via U_RxD and U_TxD 115200 Baud.
With ATD command work the voice call , but no sound both direction.
This is an "development board" from Aliexpress , 3,5mm 4 pole Yack female connector included.
I try connect Samsung headset with pushbutton volume control , maybe not recognized to the mic and speaker?
What possible problem ?
Thanks 
nernoe