Why do calls blocked on iphone still go to facetime

Recently, I have been getting 1 - 4 Spam calls a day. In order to try to prevent these calls from ringing my phone all day long, I installed an app called TrueCaller. It is supposed to help identify and block known spam calls. Today is the first day I have had it on my iphone. I noticed that when a known spam number called earlier, it did not ring my phone BUT, the call did ring through on my iPad as it was coming in. And it shows in my missed FaceTime calls on my MacBook. My phone did not ring at all or even show it on the call log. Partial success! But, HOW do I prevent them from going to all my other Apple devices? Do I just have to turn off ALL calls from going to my other devices? I like having them ring when they are legit calls. Has anyone worked with this in the past?