Out of the blue, one of my employees' mailbox is telling callers "The extension you have dialed is not available at this time."

Has anyone else had this happen to them? (and know what caused it?)

Previously, this same guy had his message waiting lamp stop working. I discovered his "Green LED Disp." value (CoS 72.04) was 38 not 36, which I reset. Since my revision of firmware requires a system reset, I did that afterwards, and his mailbox disappeared. We recreated it, and it had been working fine for about 3 weeks before the above happened.

He didn't change his active greeting number by any chance did he?

The 'unavailable' canned greeting plays if an invalid/unrecorded greeting number is selected as the active greeting.

The mailbox user could have deleted a recorded greeting, or has selected an unrecorded greeting as his active greeting. Go to the mailbox and check the selcted active greeting number, then go to greeting management and play that greeting number to verify it has been recorded.

I have seen on a few occassions greetings 'disappear' but suspect the user has unknowingly changed a setting in their malbox.