I jumpered the FL 2000 into the system and tied the lamp lead to one station so far to prove it works. Using it with a Melco KC19 tone/dial IC
The white set goes off hook and all IC lamps on all stations line 5 light, you select the called station IC number, in this case STA 4.
Station 4, Green set: Buzzer sounds and line 5 lamp goes from steady to flash until the station goes off hook. Once off hook the lamp goes steady and the interrupter stops at the next cycle.

Here are my thoughts... Its an interesting function and kinda "neato" for a collection system. However it requires a lot of wiring for such a simple thing that 99% of people wouldn't notice. Ill probably hook it up if I can get it to work reliably. I've noticed sometimes it doesn't seem to want to work the way I would expect it to so Ill play with it some more.
Thanks for all the help and advice. Heres a link to a youtube vid showing how it works: