If you’ve tried any of the call blockers, or spam identifiers in iOS 10, you’ve surely been disappointed. I’ve tested out a number of them and they really haven’t seemed to do anything at all. Most of the time not blocking, or even identifying calls. It appears we may now know why.
It looks to be an underlying issue with CallKit, Apple’s new framework that powers these types of apps.
It seems to have been a serious enough issue that Apple has reached out to some developers to let them know that they have stopped processing reviews of apps that block calls into the App Store until iOS 10.1 is released, possibly later this month.
We’ve now had a call with Apple’s app-review team and have an explanation for both. They let us know call-directory extensions, of which Callblock is one, are failing intermittently due to issues with CallKit, which is the new iOS framework Callblock uses to screen calls. The issues are expected to be resolved in iOS 10.1 and they’ve paused reviews of these extensions till 10.1 is publicly available.
Hopefully, once iOS 10.1 is released, we will start to see call blockers back on the App Store with much improved performance.
Source: Rocketship apps