Disclosed are a method and bi-directional communication device, such as a cable modem, for iteratively performing the following steps for each of a plurality of communications channels until a downstream data signal is detected. Selecting a communications channel and checking for a downstream signal having a first bandwidth complying with a first system interface standard, and if the downstream signal having said first bandwidth is not detected, then checking the communications channel for a downstream signal having a second bandwidth complying with a second system interface standard.