Abstract: The invention relates to a monitoring system equipped with low-power-consumption camera devices. A main monitor device (15) grasps whether each monitor device (12) makes a request for sending image signals. Each camera device (13) sends a polling signal to the main monitor device (15). The main monitor device (15), in response to the polling signal, sends to a camera device (13), a second relay image-sending request signal containing a piece of identification information of a monitor device (12) requesting for sending of image signals, or no-sending-request signal for relay. The camera device (13) receives the second relay image-sending request signal or the no-sending-request signal for relay so as to grasp whether sending of image signals is required or not and the monitor device (12) requesting for sending of image signals. The camera device (13) sends the image signals to the monitor device (12) requesting for sending of image signals.

Abstract: The invention relates to a monitoring system equipped with low-power-consumption camera devices. A main monitor device (15) grasps whether each monitor device (12) makes a request for sending image signals. Each camera device (13) sends a polling signal to the main monitor device (15). The main monitor device (15), in response to the polling signal, sends to a camera device (13), a second relay image-sending request signal containing a piece of identification information of a monitor device (12) requesting for sending of image signals, or no-sending-request signal for relay. The camera device (13) receives the second relay image-sending request signal or the no-sending-request signal for relay so as to grasp whether sending of image signals is required or not and the monitor device (12) requesting for sending of image signals. The camera device (13) sends the image signals to the monitor device (12) requesting for sending of image signals.

Abstract: During a call through an information and communication network, when a calling path with cheaper rate than that of the calling path which has been established becomes available, the calling path can be switched to continue the call. A call is possible between telephones in the Internet through calling paths which are selected from an IP network including an access network and ISP networks. In cases where the calling path with cheaper rate becomes available when the calling path is established and the call is carried out, connection is switched from the calling path to the calling path so that as the call is continued, a rate can be reduced.