Who called from 9722177004

Three calls from this number today.  I let them go to the answering machine and no message was left.

Let it go to VM. No message left.

This number repeatedly calls 4 & 5 times a day & without leaving a msg. We are on a do not call list. Who is this? If it's a legitimate call they would leave a msg.

I kept getting calls from this number with no messages. So, I called them back, and they are a Solar Company.