The DIC-23216 switches to 'Power Saving Mode' as soon as you disconnect the power cable; it then starts using its battery. 

It comes out of this mode as soon as someone pushes the 'call'-button on the outdoor unit.

If the DIC-23216 is connected with the power cable that comes with it, it will come out of 'Power Saving Mode' after a short while. It can then be used as a camera.

This solution is valid for DIC-23216 - DIC-23216UK