When I say "every other OS" I meant every previous version of Android - I've never used an iPhone, if that's what you were implying.
What I don't get is why that ability is built into 4.X and every version of TW, but not on pure Android? That seems stupid. I have to rely on a 3rd party (buggy at best) or adding (what has grown to) 219 *different* numbers to a single contact to block it?
I've used 3rd party apps. Mr. Number was a good one on 4.X, but is broken on 4.4 and 5.X - it blocks contacts when you've explicitly told it not to. So, maybe it will work again?
Either way, its built into TW, it was built into ICS, but since KK its gone and I feel that if every rom offers it and every "other" OS (TW, or whatever LG calls theirs) why is it left out of Vanilla Android?