A transmission system having a first transmission terminal and a second transmission terminal includes a first communications connector to connect first data communications between the first transmission terminal specified by first identification information and the second transmission terminal specified by second identification information, an identification information creating part to create fourth identification information of the second transmission terminal when receiving a request for connecting second data communications between the first transmission terminal and the second transmission terminal, and a second communications connector to acquire third identification information in association with the first identification information by referring to registration information registering the third identification information in association with the first identification information of the first transmission terminal, and connect the second data communications between the first transmission terminal specified by the third identification information and the second transmission terminal specified by the fourth identification information.