Hi BigLucy,
You're thinking is right cause you can do this with ACD2000. My problem is I am talking from a ICP3300 perspective as I don't know the SX200. If it's more or less the same you would want to program rerouting on busy to one ACD path and assign a RAD port with an interflow dialing list associated to that RAD port.
This will give you the option of recording your message with instructions to the caller.
On no answer you could send the call to a different patch with a different RAD message stating business hours etc.
I won't elaborate too much cause I'm not sure the programming is the same on the SX200.
Hope this helps,
E