Monitoring system

An intercom for a visitor comprising:

• an operation portion arranged to be manually operated by the visitor for the intercom to transmit a call signal to a destination to visit;
• a microphone arranged to pick up a voice of the visitor;
• a camera arranged to capture an image of the visitor;
• a recorder arranged to record the image of the visitor captured by the camera;
• and
• an administrator arranged to automatically add flag information to the image of the visitor recoded by the recorder, wherein the flag information is changed for a later inspection in dependence on whether or not the microphone fails to pick up the voice of the visitor who keeps silence over a predetermined time period after transmission of the call signal caused by the operation portion operated by the visitor.

An intercom for a visitor comprising:

• an operation portion arranged to be manually operated by the visitor for the intercom to transmit a call signal to a destination to visit;
• a microphone arranged to pick up a voice of the visitor;
• a camera arranged to capture an image of the visitor;
• a recorder arranged to record the image of the visitor captured by the camera;
• an administrator arranged to automatically add flag information to the image of the visitor recoded by the recorder for a later inspection in response to the microphone;
• and
• a speaker arranged to generate a voice in automatic response to transmission of the call signal caused by the operation portion operated by the visitor.