Not sure what your post means. I did you give someone - a person you don't know - the last 4 of your social? What exactly happened so we can advise you. Giving the even the last 4 is not a good idea. A good scammer or just someone who wants to harass you can make a lot of trouble with only those numbers.
Call on my cel phone. I never answer these. What I do is use Skype to call the number back to see who answers. In this case it was a company called "Trident Assets". Likely a collection call.