I use Call Blocker by Vlad Lee on my Android phone. It's set to only allow my contacts to ring through. Everyone else goes to voice mail, where I ask that if they're human to send a text. Fucking spammers ruined having a phone.
After signing up for the National Do Not Call Registry, I still periodically received telemarketing calls. So after a few weeks of cursing people out calling them dirty niggers/wetbacks/pajeet, I decided it was time to change my tactics. The next time they called, I asked for the name of the business and their address and explained that I was on the Do Not Call Registry and they were committing a federal crime. They immediately hung up and I haven't had a call in at least 4 months.
This may not work 100% of the time, but it worked for me so far.
I only have a landline (more than enough for the TLAs to eavesdrop on). I'm on the National Do Not Call Registry, which has cut down the spam calls by about 80%. I have a TeleZapper (https://www.amazon.com/Privacy-Technologies-TZ-900-TeleZapper-900/dp/B00006881R) I got from Radio Shack like ten or twenty years ago, that cuts down the remaining 20% to like 5%...and I have an answering machine I use to screen out the rest.
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