Recently we went from 4 digit extensions to 5 digit extensions. When all was said and done the voicemail lamp stopped turning on. I can see in unity that the lamp is flagged as on, but I've had no luck figuring out why it's not working. So far I'm done a master reset, changed out phones, manually tried flipping it on using 5050 to no avail. The phones are 8800 series and it seems like the problem is pretty random only affecting some phones. The VM icon shows on the screen, but no red lamp on the handset.