In a post on vishing, I warned against calling phone numbers provided by untrusted sources. The particular case I posted about involved a bogus e-mail technical support phone number. Today, a judge just shut down an outfit that pretended to provide technical support for Microsoft and Facebook.
In my previous post, I warned about vishing because there was no way to know the intentions of the people behind the number without actually making a call; vishing occurred to me as one possibility. The scheme that was just shut down, however, shows that such numbers can also be used to sell nonexistent services to victims.
Remember to never buy anything from or give any personal information to unsolicited callers. Before calling a number, make sure to check a trusted source to make sure the number is genuine. Even if you receive a call that you believe may be legitimate, it may be safer to tell the caller you will call back later at a number you know to be correct.