Many of us here at Stop-Collections.com have been the victims of robo-dialers. A robo-dialer is a robot/machine or automated process that just starts dialing a ton of numbers. When you pick up the robo-dialer and say hello, you will be connected to a representative. These are super annoying. The secret to avoiding these robo-dialers is to never say anything when you get a call from a number you do not know. Wait for the other person to say hello first. If it is a robo-dialer then it will automatically hangup.
The solution I use now is to download an app on my phone that sends all phone calls from people not on my contact list straight to voicemail. I love this but understand it might not be for everyone. If you are expecting a call from a number not in your contacts, you can easily turn it off. There are many apps that will help you with robo dialers or scammers which you can easily find by doing some cursory searches for certain keywords (phone, block, scam, dialer, etc).