It's an inmate from Washington state corrections. They might be calling you because they have the wrong number! They can't hear anything on the other end so that's probably why they are trying to call multiple times. Just listen to the recording g it gives you an option to block future calls of this nature.
This number keeps calling me... speaks what sounds like spanish (a recording) and then hangs up within seconds. I just want it to stop! I have no idea who it is, but it has become VERY irritating.