Not! Most spammers/scammers are using robo dialers which doesn't recognize unlisted or not given out numbers.  There are other way's to get folks numbers as well. But they know x to xxx are in service,  So set up a dialer for x to xxx and keep calling until it actually rings.

your cell provider sold it to them

I just received a phone call on my cell. I almost NEVER give out my cell phone number and asked the man on the other end of the line how he got it. The message left on my phone (I was driving--one reason I don't give it out) said I had indicated, online, that I was interested in employment. ???? No. I can understand making a mistake while online, but I would not have given out my cell phone number. So how did they get it?

claimed I filled an online survey.  I did not.  Offered service anyway.  A service I have no need for.

2nd or third time they have called.

Its an employment agency...WN Physicians