Why is the ACD button black?

[Belinda Frick]

The black ACD button means the status is DND(do not distrub or not available).

It will stay in this status if no update from TAPI to see current status.

It could be in the 'black' status:
Phone is set to DND.
If extension is set to forward.
Note: Some phones can be set to only forward when busy. In other words they can
take calls.