Just saw your thread - do you still need help? Dial into the main menu and press 9 + Admin mailbox number. If you don't know the Admin extension, try 399 or see if there is a phone in the switchroom. At the main menu, press 4 to change a mailbox and follow the prompts to reset the box as new. You'll lose the messages, though. If you don't know the security code (password), you may need to go back to the vendor. If you are using a display phone, follow the softkeys and press MORE, then MGR, the CHBX to delete or set the security code.