Until now, thanks to VoIP, it was very cheap to get a second incoming phone number for your private needs. Now this is free. At least two companies offer now free incoming phone numbers. And because the number can be selected from your area code nobody will ever think that the number they have is not your main number but a disposable number created specially to protect your identity and privacy.
Being free services is obvious to have some limitations. All you have to do is to study their websites and see which one fits you better and then you can freely post your phone number on any channel (web site, blog, give it to strangers, etc).