Enable call forwarding.
Option 1. Most handsets have a forward button if this is the case press the button then dial the number you want to send your calls to then press call. the handset will double beep. display should show calls are forwarded.
Option 2. Dial *02N "N is the phone number" then press call. divert should be on you will hear a double beep.
Disable call forwarding on handset.
Option 1. Most handsets have a forward button "it may say something like Clr fwd if a forward is active press the button and forward should be disabled.
Option 2. Dial *03 and call divert should be removed you will hear a double beep.