What I have completed with the local support assistance was by Creating Table that consist of the exact number to be block. Assigned that specific extension to route ALL (ONLY OPTION) inbound call to that table first. End-user change is that it will required all caller to press 0 to continue to ring the phone. So far it has blocked a lot of RoboCalls with no issue, with the exception that sometimes he forgot and ask me if his extension is in the BLOCKED list!!!!!
*****(DO NOT FORGET TO ASK THE END-USER THAT THERE WILL BE AN ADDITIONAL ACTION NEEDED FOR THE CALLER, IS IT OKAY TO PROCEDE? {My End-user agreed and INSISTED to continue!!! I send the conversations and request his permission on the email and received his INSISTED reply ~ 3 weeks later he pulled me to his office and lecturing me of not following protocol and claimed that his phone line is BLOCKED)*****