how to know if Wemo Lights are plugged?

Question

How do I find devices that have been paired with the bridge but are currently powered off?

For example if you unplug a bulb you still receive the info from the bridge as it were available using the following POST:

http://IP:49153/upnp/control/bridge1

<?xml version='1.0' encoding='utf-8'?>
                  <s:Envelope xmlns:s='http://schemas.xmlsoap.org/soap/envelope/' s:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/'>
                    <s:Body>
                      <u:GetHomeInfo xmlns:u='urn:Belkin:service:bridge:1'>
                      </u:GetHomeInfo>
                    </s:Body>
                  </s:Envelope>