recorded message. spam call

Got phone call from this number.   Caller hung up without saying anything.   Interesting there are several of us who have gotten a call from this same number.

They've called our house phone, you can hear that there is someone on the other line but they said nothing, I said "Hello?" 3 or 4 times before i hungup.

Getting calls from this number, couple times a week, in the evenings, same as above, can hear other end, as if someone there, but they do not say anything.  Tried calling the number back, and only got busy signals.  Anyone know who this is?  What happened to Google Reverse Phone Look up?

Got a call from this number at 8:02 Saturday morning.  Caller ID said "Unknown Name" and I didn't recognize the number, so I just disconnected without answering.