Sounds like a fax machine. If you call back it says no longer in service. So far 3 calls alternating with a Minnesota number also 3 calls in the last hour. So, 6 calls that sound like a fax machine and say they are no longer in service if you call them back. Wish I could figure out how to make this stop. This one is Oregon call.
I have a cool solution ... but then my Magic jack can record numbers, and I name calls like this "IGNORE".
So next call an immediate pop-up saying "IGNORE" tells me. Then, depending on my mood I can tie up their phone line until they tire, or immediately discard them with a mouse click.if I'm busy or just want to exercise control on my end. At least we (not them) decide their future.