it is something my wife's iPhone has that is simple to use and built into iOS. Guess us android folks need a app to do it
I'm confused by the above responses as I don't need an app to block numbers as it's built in to the OS (though I will admit, having a ready-made database as suggested by David, sounds appealing). I'll admit it took me a little time to get my head around it as, coming from a Windows Phone, it's very unintuitive & uses odd terminology (call reject rather than block) but my phone now has a nice long list of blocked (rejected) numbers.
I don't have a Settings > Call on my phone
I'm on Lollipop and have Settings -> Call -> Reject - thanks a bunch for this tip! Am tired of getting daily spam calls.
I don't have that option, either. I'm guessing another thing Verizon removed in its infinite wi$dom.