If you want the calls to be directly forwarded to another Phone Number, you can set up call forwarding, so that when a call is incoming, it will check where the routing is set to before connecting it.
Here are the Steps to help you setup Call Forwarding Manually:
Go to Manage Phone Systems -> Manage Phone Numbers
STEP 1 : Select the Phone Number that you would like to setup Call forwarding for. Click on "Edit selected".
STEP 2 : Click on "Advanced Options" at the bottom.
STEP 3 :
Click on the drop down for "Call Forwarding" and select "Call Forwarding - Always".
Set "Call Forwarding Destination" to the phone number that you would like the calls to be forwarded to.
STEP 4 : Click on "Update".
Here is an example of how it looks after Call Forwarding is set up.