Can I setup my current phone to forward to goodcall?

With conditional call forwarding your customers call your current phone number and are forwarded to Goodcall when you don’t answer or the line is busy.  You can enable conditional call forwarding with your current telephone provider. 

For example to enable in Comcast Business, go to the web portal and enable it in phone settings.  Many providers allow you to enable using *90 and *92.  Check your telephone provider for details.   Ask/search for conditional call forwarding.