A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side comprising a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side comprising a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.