Who called from 5712295673

I get at least one of these calls every day. They always hang up. And if I try to dial it back, I get a "not in service" response. Very frustrating.

just got the call, called them back says number not in service

Number calls, says "Uh, huh" then hangs up. This happens at least once a day.
How to you block this?

phone number 5712295673 calls 3-4 times a day everyday of the week except Saturday and Sunday. If i answer nothing is said. Whether I answer or not they keep calling back. I have a feeling this number belongs to quest diagnostics? [***] a-holes leave me alone.

Same here, has call 2 times within last hour.  Never leaves message, tried to call back and I'm told number not in service.  Very annoying. I usually do not answer 800 or out of area code calls due to solicitors.