For starts my disclamer--I have very little talent when it comes to moding the registr but heres some thought
The led blinks when the speaker phone is on as we know.
When we disable the speaker phone it can be done by the tap of the speaker phone icon on screen.
When a call is missed or voice mail present we have a notifacation icon on screen
tieing the led notifacation from the speaker phone into the call icon............................could it be that hard??????
It seems to me the reg tweak coud be done very easy.we just need to find the talent.Ive put a couple post in maltesta link provided yet no responce in over a week