Thanks for the response! I am guessing when you say TUI admin mailbox, that means dialing from my phone and managing through the admin mailbox there. I went through all the options there and the only thing close to adding a new extension was adding a new user ID. I did that and put in the 988 which is the extension of one of the new users having this issue. It allowed me to save, I then tried accessing the mailbox of that extension and was still met with "That was an invalid entry". If I manage 988 from the admin mailbox, it seems to allow me to reset the user ID but when trying to access 988s mailbox, I get the error.

I was informed that the only way to manage our voicemail was to connect via serial cable to the VM card. Is that the only way to reset the default code?

Josh