A communication system includes a first communication device and a second communication device connecting to a LAN. Using a first proxy setting for a specific proxy server, the first communication device communicates with a conference server via a proxy server to establish a session. If the session has not been established, the first communication device determines whether LAN information identifying the LAN is included in history information stored in the first communication device. If the LAN information is includes in the history information, the first communication device transmits setting request data to the second communication device identified by device information associated with the LAN information. If the second processor receives the setting request data, the second processor transmits the second proxy setting to the first communication device. The first communication device communicates with the conference server to establish a session using the received second proxy setting.