Hello & Welcome to Just Answer,
Sorry I didn't see your question earlier and to hear of the issue you are having.
May I ask:1) The Make & Model Number of the phone system you are working with?2) What phone service provider (phone company) you have for this phone line?
I see it has been a few days and I just wanted to follow up to see if you have any more questions concerning this issue or if the issue was resolved.
I asked about your service provider because "forwarding" of calls is normally set up and done using a "feature" of the service provider.
I look forward to any further questions or results that you may have.
Thanks, ***** *****