Enterasys Networks CSX6000 - Manual (Page 718)

USER’S GUIDE
718 CyberSWITCH
UNKNOWN Indicates that an event occurrent but that the network does not
provide causes for the actions that it takes, therefore the precise
nature of the event cannot be ascertained. This may, or may not,
indicate the occurrence of an error.
Dec Value Hex Value Q.931 Cause