Yes, you will need to log into a mailbox that has system manager rights, and go thru the menu until the voice mail asks "would you like to access system manager options". Press 1 for yes. Then once there, the voice mail will ask you to change different options and dial 2 for no until you get to "would you like to change the system schedule". Press 1 and the voice mail will say the current time and ask if you would like to change it. Press 1 and follow the instructions. Remember to enter the time as a 4 digit entry.