A method is provided for handling a call communication session via a communication address associated with a private network using Unstructured Supplementary Service Data protocol. The apparatus includes a device configured to be worn on a user’s head, a light source for directing light towards one or both eyes of the user, one or more image guides on the device for viewing one or both eyes of the user, and one or more cameras carried on the device and coupled to the image guides for acquiring images of the eyes andor the user’s surroundings. When the robot apparatus 1 is to find the direction and the distance to the electrical charging device 100, a CCD camera 20 finds the direction vector of the marker from the photographed image.