A read-only counter of the number of failed HDSL training attempts on this port since powerup or since it was last cleared. A rising count of failed attempts points directly to line-quality problems preventing the modem from establishing a stable connection, prompting an admin to investigate the physical loop. If cmHDSLModemFailedTrainingAttempts climbs quickly on one port while cmHDSLModemSuccessfulTrains stays flat, the admin would treat that line as actively struggling to come up and needing physical inspection.