Samsung DS5021D - Manual (Page 45)

© SAMSUNG Electronics Co., Ltd. Page 31
THINGS YOU SHOULD KNOW
7. Telephone Status Indicator
The status indicator turns on or off according to the telephone status.
Functions Status of LCD Indicators
Busy/Off-hook Steady red
Extension Ring Flashing red
Trunk Ring Flashing green
Recalling Flashing yellow
Message waiting Flashing red
Calling Denied Fast flashing red within 1-second interval.