Call from number "not in service" presumably scammer

More nuisance calls today - different number.

Who signs them up to all these numbers that obviously change so frequently?

Received a call from this number just on dinner time this evening, and let it go to our answering machine. When checking the call, they'd hung up and didn't leave a message. So, I called the number back only to find a message stating "The number you have dialed is not connected" .... so Telco's, how can this be? Obvious SCAM caller so number now blocked!