A communication system includes a first communication terminal and a second communication terminal. The first communication terminal provides first terminal identification information read out from a memory to a first mobile terminal. The second communication terminal obtains the first terminal identification information from a second mobile terminal, the second mobile terminal being a mobile terminal that has received the first terminal identification information from the first mobile terminal through a first communication session. The second communication terminal further transmits a request for starting communication with the first communication terminal to establish a second communication session with the first communication terminal.