Abstract: There is provided a method for data transmission in a communication system, including: transmitting part of data to be transmitted from one terminal to another terminal depending on a maximum transmission tolerable capacity; when the transmission of the data is stopped during the transmission, storing information on a capacity of the partial data lastly validly transmitted from said another terminal and information on a corresponding session; when a next session begins after stop of the current session, transmitting the information from said another terminal to said one terminal to recognize the information as a session upon restart; and finding, at said one terminal, data at the time when the transmission is stopped, and transmitting the data following partial data at the stopping time to said another terminal.