Panasonic kx dt 333 When the phone rings the red light doesn't flash to denote which line it's coming in on. Any idea how to resolve this?

Which means what? You have a solid red light on the line or you don't have the line at all. A TDA system rings by a process called ICD groups. You can have a phone in an ICD (600 by default) and tell it the number of rings to delay, not ring, or immediate ring, but that means that the line button will flash as the call is coming in. If you don't assign it to a group, it's really stupid and won't do anything but light solid red.

If you have access to installer programming, you assign the extension to the main ICD. If you don't you have to call your Panasonic installer or dealer.

Carl