No message, but no surprise. These scammers use caller ID spoofing, so if you try to return the call, you get a "non working number". It could be an offshore boiler room operation.
I have used a routine inspired by Tom Mabe. xxxx County Sheriff's Department.
It's simple, no message it's unimportant. If I don't recognize the area code I block. Then I block the next one and do on. It's a shame the government who has supposedly made it so we can take our name of the list to stop it hasn't, just more useless garbage out of DC that creates paperwork to imply they're doing something when they aren't. What we need is for our phone service to make it possible not to block but redirect the calls to DC and our congress person, bet they would stop the call then.