A couple of months back I was introduced to truecaller app https://play.google.com/store/apps/details?id=com.truecaller&hl=en.

“Truecaller is the world’s largest collaborative phone directory that makes it easy to get in touch with people across the globe.”

I had tried many similar apps before this which claim to show caller’s info, but none comes close to this one. This app shows location and name of the caller (well 60-70% of the time, else it will show no info available). Most importantly the app has saved me  taking unwanted calls as it shows the info about the caller like “credit card”, “customer care”, which helps me judge if I want to take the call.