I never answer a number I dont know. Especially if it seems to me that it is a scam. They never leaves a message. If it was important, they would leave a message. As for the DNCL, I am on it, it reduced the unwanted call by 95%.
My wife and I got separate texts to our cells with the same number/alert. Called it and got a recording from the Federal Trade Commission that the number had been disconnected because of it's possible connection with a phishing scam.
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