You can record a single greeting for all circumstances or one greeting for when your line is busy and another greeting for when you are unable to pick up the call. Or you can just use the default Messaging system greeting.
You can also record an Extended Absence Greeting (EAG) message to let callers know that you will be away from the office and won’t be able to reply quickly to their messages. Because Messaging only applies EAG functionality when it answers a call, the administrator can block it from recording a new message. However, this ability to block new messages is only available when the call comes through the Auto Attendant or when a user’s station sends a call to cover. Messaging will not block messages from users who compose and send a message from within their own mailbox or from their networked contacts.