popswjl2704 -- You will know when they are calling, the phone will ring once or twice and then goes to the forward process. I use it and this is what I see. Mostly when I get the calls, I see them as usual on caller ID, then they go to call forwarding to NoMoreRobo. However, like barbie123 mentioned, with spoofing some do get through, but not as much. Also, on their website, you can add the number getting through.