UPDATE: Every few months the “block” setting turns itself back to “warn” and calls start coming through again. I tried contacting Hiya support to report the bug, but they never replied to me. It also stops updating itself once in a while, even though I enabled it to run in the background and to allow push notifications. I don’t think any of the call blocking apps are perfect, but I’m frustrated with the bugs in Hiya. ORIGINAL REVIEW: To be honest, I have no idea if it's actually working because Apple does not provide any way to know if calls are actually getting blocked. That being said, I haven't had a single spam/scam call since installing Hiya! I was previously getting 4 to 5 calls per day, sometimes many more. I can only assume that means Hiya is working and doing an amazing job!