Phone rang at 8:45 am Saturday morning.  Caller ID showed Detroit,Mi area code 313.   No one spoke, no automated message left.  Just silence.  Added to my call blocker.

Unknown person called 1-2 seconds ago. Need to be blocked in definitely.
Thanks

Received a call from this number. No one said anything, it was just silence. They have called me numerous times now,  when I call the number back it rings twice then a dial tone sound.