OK, I got to thinking about this, and then I remembered that the 2000 series phones don't flash the LED on ringing. So I took one of my spare 2616's apart and started poking around and came up with something.
Right below the speaker on the printed circuit board there are six pins sticking straight up about 1/2" long. They are marked as P2 and numbered as follows:
4 5 6
x x x
x x x
1 2 3
Whenever pins are sticking up, they are there for a reason, so after poking around in a few places I found with my multi-meter that there is 5VDC voltage present when the phone rings between pins 2 and 5, and no voltage between the rings. Pin 5 is (-) and Pin 2 is (+).
So, this gives you a great place to tap 5VDC which is plenty of juice to trigger a relay that will flash whatever light you want with every ring.
Now the bad, but not-to-bad news. I tested this with SCN and got NO VOLTAGE so you will have to leave SCR on the phone and either turn down the ringer, or clip the speaker leads while your in the set (they are right there next to the pins you are working on).
I imagine a 2008 has something similar inside, but if not, you can always throw a 2616 there. Last I checked 2616s were about $15 to $20 on eBay, so you are not risking too much.
Thanks for giving me a fun project for the night!
911Guru