You can forward your incoming calls to your voice mailbox (network service). People can leave you a message, for example, when you have not answered the call.
In the home screen, select Call to open the dialer, and select and hold 1.
Change the phone number of your voice mailbox
Select Menu > Settings and Calling > Call mailbox.
Select and hold a mailbox, and from the pop-up menu, select Change number.
Enter the number (obtained from your network service provider), and select OK.