A communication system comprising: a connection control apparatus configured to receive a connection request message that requests a connection to a network from a first communication apparatus included in a plurality of communication apparatuses in which a synchronous communication is limited and allow the first communication apparatus to be temporarily connected to the network when the connection request message corresponds to a message that requests a temporary communication; and a communication timing control apparatus configured to transmit, when the communication timing control apparatus receives a communication timing request message that requests acquisition of the communication timing from the first communication apparatus while the first communication apparatus is allowed to be temporarily connected to the network , a communication allowable timing notification message indicating a communication timing to the first communication apparatus while the first communication apparatus is allowed to be temporarily connected to the network ; wherein the communication timing control apparatus is configured to start a collective accept timer when the communication timing control apparatus receives the communication timing request message from the first communication apparatus , and when the communication timing control apparatus receives the communication timing request message from a second communication apparatus included in the plurality of communication apparatuses while the collective accept timer is being activated, calculate a communication timing of the second communication apparatus and update the communication timing of the first communication apparatus . a connection control apparatus configured to receive a connection request message that requests a connection to a network from a first communication apparatus included in a plurality of communication apparatuses in which a synchronous communication is limited and allow the first communication apparatus to be temporarily connected to the network when the connection request message corresponds to a message that requests a temporary communication; and a communication timing control apparatus configured to transmit, when the communication timing control apparatus receives a communication timing request message that requests acquisition of the communication timing from the first communication apparatus while the first communication apparatus is allowed to be temporarily connected to the network , a communication allowable timing notification message indicating a communication timing to the first communication apparatus while the first communication apparatus is allowed to be temporarily connected to the network ; wherein the communication timing control apparatus is configured to start a collective accept timer when the communication timing control apparatus receives the communication timing request message from the first communication apparatus , and when the communication timing control apparatus receives the communication timing request message from a second communication apparatus included in the plurality of communication apparatuses while the collective accept timer is being activated, calculate a communication timing of the second communication apparatus and update the communication timing of the first communication apparatus . <EOS>