I don't have a user guide for Unisyn (TO616) if you have one the message waiting sequence will be in it. The DSU uses Intercom star 3 and the extention number to activate the light, and pound 3 and extention number from the activating station to turn it off.
Try that, they might be the same. If not, you need to locate a user guide for your system.
Please complete your profile.
Mark



[This message has been edited by markk (edited January 20, 2005).]