These are scam calls as you have already suspected. The scammers' aim is generally to gain remote access to your computer and, from there, to your online banking with a view to stealing money from you.
The simplest way to deal with the calls is to hang up and not engage with them. Alternatively let all calls go to answering machine and screen out the scam calls.
The best way to deal with the scam calls is with a device, or phone, which screens out the calls and prevents the scam calls from ringing your phone. See a recent post below for a fuller explanation
https://community.virginmedia.com/t5/Home-Phone/Landline-handset-to-block-unwanted-calls/m-p/4573945...