Digital subscriber line communicating system

A digital subscriber line communicating system having a central office and a remote terminal are connected through a telephone line, and are subjected to cross-talk due to a TCM-ISDN transmission at the receiving side. The communication uses a dual bitmap loading scheme in accordance with the FEXT/NEXT condition at the remote terminal. During training, the central office sends a symbol, named "switching symbol" to inform the remote terminal that the train sequence will switch from the first bitmap to the second bitmap. The "switching symbol" is sent in the FEXT period of the remote terminal.