A communication terminal (10, 70a, 70d, 90a) comprising: a processor (101, 701, 901) configured to output terminal identification information identifying the communication terminal (10, 70a, 70d, 90a); a receiver (111, 705, 911) configured to receive instructions to start communication with a counterpart communication terminal including external terminal identification information identifying an external communication terminal communicating with the counterpart communication terminal, the external terminal identification information being sent from the external communication terminal through a communication management system to a destination address of the communication terminal (10, 70a, 70d, 90a) indicated by the terminal identification information; and a transmitter (111, 705, 911) configured to transmit, when requesting to start communication with the counterpart communication terminal, the received external terminal identification information to the communication management system, instead of the terminal identification information of the communication terminal (10, 70a, 70d, 90a), wherein the transmitter (111, 705, 911) is configured to transmit to the communication management system first status information indicating that the communication terminal (10, 70a, 70d, 90a) is communicating and second status information indicating that the external communication terminal is communicating, and wherein in response to receiving an instruction for ending the communication with the counterpart communication terminal, the transmitter (111, 705, 911) is configured to transmit to the communication management system a communication exit request requesting the communication terminal (10, 70a, 70d, 90a) to exit the communication and a disconnection request requesting to disconnect communication of the external communication terminal with the communication terminal (10, 70a, 70d, 90a). a processor (101, 701, 901) configured to output terminal identification information identifying the communication terminal (10, 70a, 70d, 90a); a receiver (111, 705, 911) configured to receive instructions to start communication with a counterpart communication terminal including external terminal identification information identifying an external communication terminal communicating with the counterpart communication terminal, the external terminal identification information being sent from the external communication terminal through a communication management system to a destination address of the communication terminal (10, 70a, 70d, 90a) indicated by the terminal identification information; and a transmitter (111, 705, 911) configured to transmit, when requesting to start communication with the counterpart communication terminal, the received external terminal identification information to the communication management system, instead of the terminal identification information of the communication terminal (10, 70a, 70d, 90a), wherein the transmitter (111, 705, 911) is configured to transmit to the communication management system first status information indicating that the communication terminal (10, 70a, 70d, 90a) is communicating and second status information indicating that the external communication terminal is communicating, and wherein in response to receiving an instruction for ending the communication with the counterpart communication terminal, the transmitter (111, 705, 911) is configured to transmit to the communication management system a communication exit request requesting the communication terminal (10, 70a, 70d, 90a) to exit the communication and a disconnection request requesting to disconnect communication of the external communication terminal with the communication terminal (10, 70a, 70d, 90a).