Viking Electronics VK-LM-1A Universal Message Waiting Light
-Compatible with any telephone system with standard DC message waiting voltages ranging from 90VDC to 120 VDC
Fully modular for quick plug-in installation by non-telephone personnel
Unit's LED will blink at a steady rate when the message waiting voltage is detected.
Flickers when the phone rings
Easy retrofit mounting
Works with nearly all message waiting voltages
Not compatible with any AT&T phone system