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If you can't answer your calls, you can divert them to another number.
Find "Call forwarding"
Slide two fingers down the display starting from the top edge of your phone.
Press Call forwarding.
Select divert type
The current settings are displayed.
Press one of the following options:
Forward when busy
Forward when unanswered
Forward when unreachable
Divert calls to alternative number
Key in the required number and press Enable.
Return to the home screen
Press the home icon to return to the home screen.