I called the number back and they are with Register.com. I signed up a web domain with them and their automated telephone services was calling me to see how it was going. The rep said that if you do not pick up quickly, their automated dialer hangs up.

For the past couple of weeks, I have been getting calls from this number. I pick up and then the other end hangs up.

Received a call today and two days ago.  Didn't answer