OK - where there's a will there's a way. Here's how it can be done.

We put an analog extension number into message delivery (box 150 matching the analog port) with 14 L's (long pause) behind it. Set it to try every 2 minutes with 99 for repeat setting. Then we put a 'behive lamp' (Viking LM-1A) on the analog port. When a message is recieved in the box it does what it's programmed to do in the message delivery area. The analog port rings and to the customer looks like a message lamp. When the message is retrieved the lamp stops. The only drawback is there is about a 20 second pause between each cycle of the message delivery.