Who called from 7208623851

Received 3 calls from NBI of Colorado 720-862-3851 within 2 hours since 8am and this is not the first time, no message left on answering machine.  Use my mobile to call back and it said that 720-862-3851 number is not yet in service.  How can a number that is not yet in service keep calling my home phone every day about 10 times a day?

No message left. Did the same as Anna and got the same result "this ring central number is not yet activated."    Caller is shows NBI of Colorado

this number calls several times per day, i one day answered and actually spoke to a person, i told them i was not interested and to remove my number, the calls have started up again. extremely annoying.

Just called back. Some echo solar outfit wanting to do a roof inspection. Spoofing their number and the name. Who can we report these to?

This number has been calling me for three days how do I STOP THESE UNWANTED CALLS!   They call two to three times a day.  I am on the no call list. Who are these idiots!?