Yeah, it is a bit of a odd feature but you are right the software aspect of it makes it a lot easier. I wont post a pic of my backboard (because its a mess) but in order for it to work on my system I have a Melco intercom and its 66 block then the FL2000 and its block plus all the associated wiring.
The FL2000 is just a transistor board with a couple of relays. When the intercom line is activated off hook all line lights go on. Dialing an intercom extension then triggers the FL2000 (connected to the station buzzer lead from the intercom) to start the interrupter and then flashes the called extension. If you leave the calling extension off hook the called extension will continue to blink forever presumably. If you stay off hook and dial another intercom extension the FL2000 will change and blink the new extension. Hanging up the calling extension cancels the interrupter and drops all the line lights.
Neat but COMPLETELY superfluous in general
Shawn
