I have an Electra Elite 48 with DTU-16D phones. One of the keys on our phones is to access voicemail. When you hit that it asks for your password.

Normally that light only comes on when someone is leaving a voicemail, or when you are accessing your voicemail.

This light is on constantly right now. Our phones and voicemail are working, so I'm not sure what the problem is. Should I be worried?

If someone were calling in and leaving a voicemail, one of the phone lines would also be lit up. They are not.