Call diversions can be enabled in a number of ways, the easiest of which is to enable 'Call Forward All' on the inbound route.
Select 'Call Routing' from the PBX homepage.
Find the number for which you wish to enable call forwarding on and then click 'view/edit'.
Scroll down until you see the 'Enable Forward All' option.
Make sure that it is ticked and note down the 'Allocated Dial Code'
To Enable Call Forwarding: Dial the allocated dial code, followed by the destination.
To Disable Call Forwarding: Dial the allocated dial code, and after the tone, hangup.