New site, messed up programming.

Flash system and seven 7316e phones, have two intercoms and three lines appearing on each, plus DND and internal extensions programmed on the function keys that have display.

I need to get the display to show when an extension is in use, so the rest of the office can see that 23 is busy, for instance.

One phone has this functionality when the set is placed in DND, but does not go solid for off-hook.

Any suggestions?