Location of blocked numbers within iTunes backup Tools such as iExplorer allow you to easily browse through an iTunes backup and it's contents, and then things like the plist command for converting preferences down to readable XML. Where would the location of the plist or sqlite DB that contains blocked numbers on an iPhone such as described in the apple docs?
I looked into your question, and I think it might not be possible to find blocked numbers within a backup (or at least not in a recognizable form). I know that it is possible to find these numbers if you have messages synced with iCloud. Through the messages app on a Mac, you can go to preferences (⌘ + ,), and from there view any blocked numbers that are synced. 



I am still looking through finding the blocked numbers in the backups myself, but I am unsure that I will find them there. If I come across more I will edit the answer further. 

I hope this helps and best of luck of finding the blocked numbers through that backup.

(I am new to StackExchange, so I appreciate any feedback that would help me improve my answers or how/when I answer)