A communication management system, comprising: a control unit configured, when communication has been established between one or more communication terminals on one side, and a plurality of communication terminals on another side, to execute control for starting transmission of content data of the communication terminals on the one side to the communication terminals on the other side; and a reception unit configured, when the control has been executed for starting the transmission of the content data of the communication terminals on the one side to the communication terminals on the other side, to receive start information for starting the transmission of content data of the communication terminal on the other side to one of the communication terminals on the one side, from the communication terminal on the other side, wherein the control unit executes, based on the start information, the control for starting the transmission of the content data of the communication terminal on the other side being a transmission source of the start information, to the communication terminal on the one side, wherein the reception unit further receives a request for starting a call with the other side from the communication terminal on the one side, the communication management system further comprising: a transmitter unit configured to transmit an indication of a reception of the request for starting a call from the one side, to the communication terminals on the other side, characterized in that after the control has been executed for starting the transmission of the content data of the communication terminal on the other side being the transmission source of the start information, to the communication terminal on the one side, the transmitter unit transmits an indication that the communication terminal on the one side has become ready to start calling, to the communication terminals on the other side. a control unit configured, when communication has been established between one or more communication terminals on one side, and a plurality of communication terminals on another side, to execute control for starting transmission of content data of the communication terminals on the one side to the communication terminals on the other side; and a reception unit configured, when the control has been executed for starting the transmission of the content data of the communication terminals on the one side to the communication terminals on the other side, to receive start information for starting the transmission of content data of the communication terminal on the other side to one of the communication terminals on the one side, from the communication terminal on the other side, wherein the control unit executes, based on the start information, the control for starting the transmission of the content data of the communication terminal on the other side being a transmission source of the start information, to the communication terminal on the one side, wherein the reception unit further receives a request for starting a call with the other side from the communication terminal on the one side, the communication management system further comprising: a transmitter unit configured to transmit an indication of a reception of the request for starting a call from the one side, to the communication terminals on the other side, characterized in that after the control has been executed for starting the transmission of the content data of the communication terminal on the other side being the transmission source of the start information, to the communication terminal on the one side, the transmitter unit transmits an indication that the communication terminal on the one side has become ready to start calling, to the communication terminals on the other side. a transmitter unit configured to transmit an indication of a reception of the request for starting a call from the one side, to the communication terminals on the other side, characterized in that after the control has been executed for starting the transmission of the content data of the communication terminal on the other side being the transmission source of the start information, to the communication terminal on the one side, the transmitter unit transmits an indication that the communication terminal on the one side has become ready to start calling, to the communication terminals on the other side.