I have a customer that runs a virtual PA service. They give out dedicated numbers to clients, and based on the call, I change the Alpha part using (old syntax) SetCIDName before the phones ring so that they know to answer in the name of the appropriate company. This works fine
If the person calling the service has callerID withheld, all the phones present is Unknown in both the number AND alpha parts. It’s almost as if CID is set to NULL and any attempts to manipulate it fail.