Information can be obtained from various sources. The operation in question is using caller id spoofing and that is the tell tale sign of a bogus operation. The operations tend to go after the vulnerable. Seniors are often a primary target and I believe that is the reason for the calls my mother has received. Thankfully she knows to ignore the calls.
Sounds like a bunch of scammers in the back ground. When asked to leave a message they keep saying "Hello". Heard someone in the back ground say "Say good-by," Anyone that will call with a 000 number is up to no good. Will report unwanted calls. We have sickness in our family and I will gladly prosecute if found who this is. Do not call list is a JOKE OF THE GOVERNMENT.
The Do Not Call List is not a "joke of the government"; what a stupid thing to say. Legitimate telemarketers must pay to subscribe to the DNC list. They aren't interested in wasting their time or yours on callers who aren't going to buy their products or services. It's the scammers who pay no attention to it, scammers who use automatic dialers and make the robocalls and call from other countries, etc. to harass you. You can't block them because they call from phony ("spoofed") numbers. Don't argue with them and don't call them back because then they know they've reached a live number and will continue to call. If you catch them calling you, disconnect before VM picks up.