VM Only Plays Busy Message

Greetings-

A few of our employees have recently gone part-time and would like to take advantage of the Busy and Unavailable messages to, at least in part, announce to the caller whether or not it is their day off. The problem that I’ve run into is that no matter what, the voicemail always plays the busy message and never the unavailable.

I have let the telephone ring without answering, put the phone on busy (at the server), put the phone on busy (at the phone level), and busied out the lines so the phone could not get another call.

I’m sure there there is something small that I’ve missed. Any help is greatly appreciated.