Summarize:

” ”   Going forward, all incoming calls will be transferred to the phone number you specified. Alternately, you can tap specifically on the call forwarding setting you want changed. For example, if you only want calls transferred when you are outside of a service area, select “If Not Reachable.”
Tap on or press the green “Send” or “Call” button on your Blackberry. Press the Blackberry Menu key to access your phone's call settings. Scroll to and select “Options,” then “Call Forwarding. Press the Blackberry Menu key and select “New Number. Enter the phone number to which you want all incoming calls transferred. Click on the trackball or select the option to save the new number. Select “Forward All Calls” and press the Escape button.