'Initialize the sensor.'

def __init__(self, hass, name, port, modem):

    self._attributes = {'cid_time': 0, 'cid_number': '', 'cid_name': ''}
    self._name = name
    self.port = port
    self.modem = modem
    self._state = STATE_IDLE
    modem.registercallback(self._incomingcallcallback)
    hass.bus.listen_once(EVENT_HOMEASSISTANT_STOP, self._stop_modem)
