Hershel,
Here are the basics for BLFs on the 5000.
Continuously Lit: The extension is busy or off-hook.
Slowly flashing: The extension is in Do-Not-Disturb (DND).
Quickly flashing: The extension has a call ringing in.
Continuously flashing: The extension is causing a “Station Off-Hook” system alarm.
Have them hang up the phone properly.
Thanks,
TE