A transmission terminal comprising: a memory configured to store first preferential rating information indicating a preferential rating of the transmission terminal in using each of a plurality of relay devices being part of a videoconference system or a teleconference system; a transmitter configured to transmit a start request for starting communication with a counterpart transmission terminal (10ba, 10db); a receiver configured to receive second preferential rating information indicating a preferential rating of the counterpart transmission terminal (10ba, 10db) in using each of the plurality of relay devices, the second preferential rating information being transmitted from the counterpart transmission terminal (10ba, 10db) in response to the start request; and a selector configured to select one relay device to relay content data between the transmission terminal and the counterpart transmission terminal (10ba, 10db), from the plurality of relay devices, using the first preferential rating information and the second preferential rating information, characterized in that the first and second preferential rating information comprise a relay device ID and a value of the preferential rating for each relay device, wherein the value of the preferential rating is settable by a user of each terminal (10aa, 10ba, 10db) or an administrator of a management system connected to the terminals (10aa, 10ba, 10db) via a communication network, wherein the first preferential rating information associates, for each one of the plurality of relay devices, relay device identification information for identifying the relay device and the preferential rating of the transmission terminal in using the relay device, and the second preferential rating information associates, for each one of the plurality of relay devices, relay device identification information for identifying the relay device and the preferential rating of the counterpart transmission terminal (10ba, 10db) in using the relay device, wherein the selector is further configured to add, for each of the relay devices identified by the same relay device identification information, the preferential rating of the relay device indicated by the first preferential rating information and the preferential rating of the relay device indicated by the second preferential rating information, to derive a total preferential rating in using the relay device, and select at least one relay device having a highest value of total preferential rating, as the relay device to relay content data. a memory configured to store first preferential rating information indicating a preferential rating of the transmission terminal in using each of a plurality of relay devices being part of a videoconference system or a teleconference system; a transmitter configured to transmit a start request for starting communication with a counterpart transmission terminal (10ba, 10db); a receiver configured to receive second preferential rating information indicating a preferential rating of the counterpart transmission terminal (10ba, 10db) in using each of the plurality of relay devices, the second preferential rating information being transmitted from the counterpart transmission terminal (10ba, 10db) in response to the start request; and a selector configured to select one relay device to relay content data between the transmission terminal and the counterpart transmission terminal (10ba, 10db), from the plurality of relay devices, using the first preferential rating information and the second preferential rating information, characterized in that the first and second preferential rating information comprise a relay device ID and a value of the preferential rating for each relay device, wherein the value of the preferential rating is settable by a user of each terminal (10aa, 10ba, 10db) or an administrator of a management system connected to the terminals (10aa, 10ba, 10db) via a communication network, wherein the first preferential rating information associates, for each one of the plurality of relay devices, relay device identification information for identifying the relay device and the preferential rating of the transmission terminal in using the relay device, and the second preferential rating information associates, for each one of the plurality of relay devices, relay device identification information for identifying the relay device and the preferential rating of the counterpart transmission terminal (10ba, 10db) in using the relay device, wherein the selector is further configured to add, for each of the relay devices identified by the same relay device identification information, the preferential rating of the relay device indicated by the first preferential rating information and the preferential rating of the relay device indicated by the second preferential rating information, to derive a total preferential rating in using the relay device, and select at least one relay device having a highest value of total preferential rating, as the relay device to relay content data.