I've been using Hiya. Sure, it's not as effective as RCB (you can get a ring or two "through") but I like that it's crowdsourced, so I don't need to know what spammer is calling me beforehand. I don't get many calls from the "same" place... but I get lots from various sources, so this is a nice broad-based solution. What's more, being in sales, if an unknown caller comes in, it can often give me a name even if they're not in my contacts. So, it's not perfect, but works rather well... so, I just wanted to give this recommendation to others.