Chances are those customers have not upgraded their modem's firmware to the
latest version (most are 1.0xx or the newer 1.1xx). If these people have a
K56Flex firmware version that's below 1.0, they will run into all sorts of
problems unless they disable their 56k or better yet--upgrade the firmware.
Symptoms are usually multiple retrains, delays in data transfer,
inconsistent connection speeds, protocol negotiation problems (error
control, etc.), dropping of carrier (AscendDisconnectCause=11) and/or loss
of signal from remote end (AscendDisconnectCause=185)...