You can forward calls to your voice mailbox, where callers can leave you a message if you don't answer. Voice mailbox is a network service.
On the home screen, select , then select and hold 1.
Change the phone number of your voice mailbox
Select > Settings and Calling > Call mailbox.
Select and hold the mailbox, then select Change number.
Type in the number (ask your network service provider for it), then select OK.