According to No More Calls, they have 20 complaints. No one knows who is calling because they hang up when you answer. This is probably one of those callers testing to see if your number is a valid phone number. If they find out it is, they sell their list of valid phone numbers to telemarketers.
The method I've been using when I see the phone number is one I don't recognize is this: I lift the received and place it back down again thus disconnecting the call. If they continue to call, I keep doing the same thing. Eventually, they quit because they think the number is no longer a working number.
Called my cell...didn't leave a message. Sure it is a scam caller. Received six calls yesterday...all different numbers in different states. No message.