Is there a way to configure (with or without an app) an Android phone to forward calls from only certain numbers/callers to another number? I'm not interested in call screening; I'm looking for a way for this to happen silently in the background.
I doubt that this is possible for an app to do. This is simply because an app can recognize the number only if the incoming call request has reached the phone and by then, is too late for a call forward and the only options are to hang up or answer.
In essence this has to be supported at the operator level and that is not also going to work as they cannot configure for a specific contact.
When searched the Internet, I saw the following from Verizon's page:
Select Call Forwarding (Special)
Using Select Call Forwarding, you can program your phone to forward incoming calls from a pre-selected list of numbers to a different number of your choice. The number you choose can be a cellular phone, a pager, or another phone number. Normal local or toll charges may apply to forwarded calls.
Your Select Call Forwarding list is limited to either 6 or 12 numbers, depending on your region. Only calls from your list of numbers will be forwarded; all other calls will ring at your regular number.
You can change, add, or delete the numbers on your list at any time. Also, you can turn your Select Call Forwarding service temporarily off without changing your list.
All calling features are subject to availability and compatibility restrictions.