So today my CID says 1-671-834-3145 GUAM called at 4PM.
The call blocker prevented all but the first ring, and since the number is not on my white list (I don't think I know anyone in GUAM) no one could leave a message.
So I looked up the area code and  834 is not among the active phone exchanges.  It's just another scam/spam/fraud.