Since the modem communicates with the MUT at 9600 bps, but can communicate with the remote modem at any speed, the modem must use flow control to avoid data overruns. The only flow control supported by the debug kernel is XON/XOFF. The only problem this causes is when the remote user wants to pause a continuous data display by pressing CTRL-S. If the modem has also sent a CTRL-S, the one from the user will be ignored. You may have to press CTRL-S several times before the display pauses. This is not a problem if the remote user's communications program supports a "scroll-back buffer," in which case there is no reason to pause the display with CTRL-S.