The unfortunately reality these days is that spammers often "spoof" caller IDs to make it look like the calls are coming from somebody the callee knows so they pick up the phone. Just like in the old days of spam emails where you could "spoof" anybody's email address and make it look like the message came from someone else, the same thing has been happening the last few years with telephone calls. Unlike emails, which have implemented security measures more quickly, there's literally not a thing we can do about the spoofed phone calls today, short of changing your phone number altogether.
There is hope, though! The FCC is working to get telephone providers to implement solutions to this issue, but progress has been very slow. You may have noticed that sometimes a mobile phone call will come through with a Caller ID with a checkmark or say authenticated next to it. That's the first step in this progress - simply authenticating calls that are within the same provider (Verizon to Verizon, for example). Some providers haven't even made it this far, but other providers are starting to interchange calls that are authenticated.
Here's an article from the FCC that's mostly a bunch of technical mumbo-jumbo, but it might give you hope that help is on the way. Progress has been very slow, though, and we expect it will take years for this scourge to finally be brought under control...