Find "Voice call"
Press Apps.
Press Phone.
Press the Menu key.
Press Call settings.
Press Call forwarding.
Press Voice call.
Select divert type
The current settings are displayed.
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Press one of the following options:
Always forward
Always forward
Forward when busy
Forward when unanswered
Forward when unreachable
Divert calls to voicemail
Key in (prefix) 5 (your phone number) and press Enable.
Exit
Press the Home key to return to standby mode.