A grid change controller within a particular grid environment detects an unintended change within that grid environment. An indentation is formed in the channel. A \u201cpreferences\u201d screen is presented to a user to enable the user to input his or her privacy preferences during a subsequent chat session before the user actually logs-into the chat session. The network establishes connections with a predetermined number of terminals by transmitting an RRC connection setup message on the second channel and transmits a single RRC connection-not-required message to the plurality of terminals on the first channel. The resistor has a structure in which an effective length of the second resistor element between the first resistor elements varies in accordance with a position of the second resistor element relative to the first resistor elements. While varying the amount of timing shift, the control unit produces a plurality of packet signals and appends an identification number, with which to uniquely identify each of the plurality of produced packet signals, to each of the packet signals.