Depends on what phone your using. On a landline, your phone or company may offer a call blocking service and you can see if you can do it that way. A call blocking device has earned high praise and is often recommended by the smarter posters on here if you wish to spend around $40 or so on Amazon.
Your phone may also allow you to set numbers up so they don't ring at all.
If you've got a cell phone, visit your app store and look for a good call blocking app. Some may already allow you to block numbers, too, even without an app.
I personally don't have a call blocker for my landline and can only block 10 numbers at a time on my phone. I simply ignore all unknown numbers and look up the ones I missed. I turned off my answering machine for my landline as well so the callers get absolutely nothing from it but a ringing phone. I've gone weeks at a time without my line ringing at all--I was getting slammed almost on a daily basis.
I wish you well in stopping the bothersome calls. As I said, they call who answers, and eventually get tired of calling numbers that have no answer of any kind. It takes time and patience, but could bring you results you'll be pleased with.
This person calls & never says a word. I hang up and he/she calls back 10 to 15 minutes later. I let the answering machine answer and they don't leave a message. This is so annoying. Right now I'm trying to complain to Comcast but I've been on hold for 20 minutes. Wtf.
Constantly getting calls from (707) 243-2490 - call display reads: VEXAROS. I am receiving about 3 calls everyday around 1:00 p.m. and at least 4 calls every evening within minutes apart. They do not leave a message; it's very annoying. I don't pick up the phone if I don't recognize the name or number on the phone display.