Q2698 : can't remove sidetone?


I would like to use a free-hands kit with a Q2698 , so after AT+SIDET=0,0 command I should not hear anything in the speaker when talking in the mic. However, I still have a “larsen”. I have reduced mic gain and speaker gain so larsen effect is less easy to catch but i still hear my voice in the HP when speaking.
When sidetone is activated, sound in the speaker is louder. It means that sidetone command is valid but doesn’t remove completely the loopback.

Does anyone has already use a free-hands kit with a FX100 or Q2698 ?


Best regards,