From this portal https://nettalkconnect.com
Log in and go to account manager.
>Click MANAGE under the picture of your DUO device
>Click MORE OPTIONS
Then another window will show up and from there:
>Click PHONE NUMBERS:
>Click the AUTO FORWARD button and you can add, edit or delete numbers from there.
If your call forwarding is not working:
When you add a number to the call forwarding list, it must have a priority greater than 1.
If you want to have the call go directly to the 2nd number, simply unplug the DUO from the power and calls will go straight to Priority #2