gsm_off()
{
	# turn VBAT off
	echo 1 > /sys/class/gpio/gpio$1/value
	# release PWR_KEY
	echo 0 > /sys/class/gpio/gpio$2/value
}

	_on=66
	_pwr=70
	_status=72

		# set lines' mode and initial state
		echo "out" > /sys/class/gpio/gpio$_pwr/direction
		echo "out" > /sys/class/gpio/gpio$_on/direction
		echo "in" > /sys/class/gpio/gpio$_status/direction
		gsm_off $_pwr $_on