I got one too. I recently filled out serveys offer things like free gift cards for a game I was playing called Gaia online, but I thought I hadn't finished any of them. But T recieved two calls and when I call back, it says the number dosn't work.
this number called me three times yesterday once in the morning once in the afternoon and once at night. Every time they called I answered and they didn't say anything but just hung up on me. When i called it back it was a non-working number