Note: Currently this feature appears to work for only certain Telstra customers using certain phone services. 

You can open your Telstra app or call telstra support to setup call forwarding.

To turn on:

1. Dial * 2 1
2. Enter your Voicee number you want to forward calls to, followed by #
   
3. Make sure you include your area code, for example: *21 0XXXXXXXX #

To turn off:

1. Dial # 2 1 #