Abstract: A signaling technique for use with an asynchronous transfer mode (ATM) over asymmetric digital subscriber line (ADSL) system is disclosed. The ATM over ADSL system employs an ATM multiplexer (MUX) operatively connected to a number of downstream ATM devices and operatively connected to an upstream ATM switch. The MUX is configured to receive and process upstream setup messages that originate from the downstream ATM devices. In response to an upstream message cell, the MUX compares the call reference number (CRN) contained in the setup message with a table of CRN values associated with other calls. If necessary, the MUX assigns a new CRN value to the current setup message such that the current connection with the originating downstream device is uniquely identified by the assigned CRN. The MUX uses a CRN mapping table to facilitate the unambiguous downstream routing of subsequent signaling cells.