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 .