How to make a handsfree call programatically

Question

I'm trying to program a hands free call when a user push a button.

Up to now, I'm able to make a call but I can't enable hands free mode.

I tried this answer but it doesn't work for me.

This is a sample of my code:

private void callCaregiver(String number){
        Intent callIntent = new Intent(Intent.ACTION_CALL, Uri.parse("tel:"+number.trim()));          
        enableHandsFree();           
        startActivity(callIntent);
    }

    private void enableHandsFree(){
        Class audioSystemClass = Class.forName("android.media.AudioSystem");
        Method setForceUse = audioSystemClass.getMethod("setForceUse", int.class, int.class);
        // First 1 == FOR_MEDIA, second 1 == FORCE_SPEAKER. To go back to the default
        // behavior, use FORCE_NONE (0).
        setForceUse.invoke(null, 1, 1);
    }

Does anybody any know another way to make it work?