A blinking DSS light could mean a few things. In Hotel mode it would flash to show when telephones are restricted, the room is not occupied. When a Call Center Supervisior has the DSS it will flash fast when an extension is logged into the group or flash slow when The extension is logged out of the group and the After Call Work feature is active. You would have to touch the message active status button on the DSS (last row first button on left)to see who has messages. If then you have a flashing light it means that numbered Calling group queue is at or above Threshold 1 and below Threshold 3. Not an individual ext.