Judging from the posts below from April 2015, they'rrrrrrre baaaaaaaack. I got the first ring/hang up, googled the number and clicked on this site to see what the low down was.
They are still trying -one ring and a hang-up - a computer looking for active numbers...
This was the first time on my cell - normally they call what used to be a land line ,
I changed it to a cell three year ago - I receive many computer calls on it - maybe one per week...