If you're like me (before I fixed the problem) and you are plagued with obnoxious robodial scammers calling you frequently (anywhere from once a week to multiple times a day), you are absolutely sick of it. The calls from weird numbers that end up being recordings from "your credit card company" or a "reputable free giveaway company" and are just trying to phish your credit card information and/or steal your identity. The numbers aren't associated with any listings online, and when you try to call them back, you don't get anywhere.
Thankfully, Verizon has a spam filter option that you can turn on through your My Verizon account management page! I turned it on a month or so ago, and I haven't received a SINGLE robodial scam call since. Check it out. It's a lot more effective than apps that claim to block spammers. Not sure what Verizon figured out in terms of an algorithm for filtering those calls, but it works like gangbusters.
Just thought I'd let people know, since I've noticed a fair number of posts regarding spam calls and telemarketers that SHOULD NOT be calling your cellphones, especially if you're on the National Do Not Call list (what a farce that is... I've filed probably thirty complaints with the FCC over DNC violations, and not only did the FCC never follow up with me on even one of those complaints, but one number I complained about continued to call me for six months after the complaint...)