I went into the CUE gui and saw that the status stated "in use" for this GDM. I checked the mailbox and unlocked it from the GUI. now it's working again.
The problem's solved at least for now.. Does anyone know why this has happened?
What software pak are you running?
Had this same issue on a UC560 running SP 8.1 on Tuesday - had to go into the CLI (with Support Center permission) to unlock it because the new Web interface for CUE 8.0.3 doesn't let you do this any more from GUI.
I investigated with the Engineering team and Nazmi informed me that "mailbox in use" can come if any TUI session or VoiceView sessions are open in any other phones having access to that GDM or the ports have become stuck or busy.
For more information you can refer
Well here is the way I fixed it through CCA
From CCA/Troubleshoot/CUE Exec Commands/
voicemail mailbox unlock owner jennifer
in the above example the box that belongs to jennifer was stuck.
alternatively, you can use the number to which the voicemail box is assigned:
voicemail Mailbox unlock telephonenumber
CCA has its own CLI interface so you don't have to use putty, my preference is to use a command line program (SecureCRT) as I am more familiar with it and can do things quite quickly in it (Love the multiple tabs). The CCA command line system is actually quite good for noobies and it works quite well.
But I do take your point though, they are quite valid.