How to force PSM mode on BG95

Could you please tell me AT commands to switch BG95 to PSM mode, even when not registered to the network? Especially when AT+CFUN=0. Or share link to corresponding discussion / document? I tried already to call AT+QSCLK=1 and deassert DTR line. Indeed, device is not accepting new commands, however still draws ~30mA of current. I would like to reach level of PSM (few microamps). Simple powering down (AT+QPOWD) actually does what I need, but it is OFF state instead of PSM (OFF is less economical).