Sep 27, 2016
They got it from your domain registration. Go to whois [dot] domaintools [dot] com [slash] your-domain-name.com and you can see your name, address, phone number and email address.
This is why you should either use a "proxy" (hidden) registration option, or your job title and company name rather than your actual name, when registering a domain name. Also, set up a Google Voice (go to voice [dot] google [dot] com and register and get a free phone number that you can have forward to your real number during the registration process, but then automatically send the calls to Google's built-in voicemail (without ringing your real phone) from then on.